Laura A. Flashman, Ph.D., ABPP
Fadi M. Tayim, Ph.D.
Robert M. Roth, Ph.D., ABPP
Clinical neuropsychologists are trained in the science of brain-behavior relationships. They assess brain function by making inferences based on an individual’s cognitive, sensorimotor, emotional, and social behavior. The clinical neuropsychologist specializes in the application of assessment and intervention principles based on the scientific study of human behavior across the life span as it relates to normal and abnormal functioning of the central nervous system.
During the early history of neuropsychology, these assessments were often the most direct measure of brain integrity. Whereas neuropsychological measures remain the major diagnostic modality for some conditions, advances in neuroimaging have permitted more accurate localization of illness or injury and have resulted in a shift in the focus of neuropsychological assessment from the localization of possible brain damage to a better understanding of specific brain-behavior relations and the psychosocial consequences of brain dysfunction.
Professionals in the field of neuropsychology typically have backgrounds in clinical psychology, psychiatry, neurology, and language pathology, to name the most common contributing disciplines. Qualified individuals have expertise both in brain-behavior relations and in skills in diagnostic assessment and in counseling (Barth et al. 2003; Hannay 1998). Clinical neuropsychology is a specialty that is formally recognized by the American Psychological Association and the Canadian Psychological Association. Education and training in clinical neuropsychology have evolved along with the development of the specialty itself. The Houston Guidelines were developed to document a widely recognized and accepted model of integrated education and training that is both programmatic and competency based (Hannay 1998). Specialization begins at the doctoral level and continues with an internship and a 2-year residency program, with clinical, didactic, and academic training. A growing number of neuropsychologists have qualified for proficiency in this subspecialty area, earning the American Board of Professional Psychology’s award of Diploma in Clinical Neuropsychology (Bieliauskas and Matthews 1987), and as of 2014, subspecialty certification in pediatric clinical neuropsychology is also recognized. Beginning in 2015, a board-certified neuropsychologist is required to complete maintenance of certification (MOC) every 10 years. The MOC model asserts that competence is established at the time of initial board certification and is continuously updated through lifelong learning (continuing education), ongoing participation in professional activities, and self-evaluation related to core competencies.
Patients may be referred to a neuropsychologist for assessment for a number of reasons. An evaluation can provide information about the nature and severity of a patient’s cognition, emotional status, personality characteristics, social behavior, and adaptation to his or her conditions. A patient’s potential for independent living and productive activity can be inferred from these data. Information about his or her behavioral strengths and weaknesses provides a foundation for treatment planning, vocational training, competency determination, and counseling for both the patient and his or her family. Neuropsychological assessment is often requested in cases of Alzheimer’s disease and related dementing disorders and other progressive diseases (e.g., Parkinson’s disease, Huntington’s disease, multiple sclerosis), as well as for cerebrovascular disorders, traumatic brain injury (TBI), tumors, seizures, developmental disorders, infections, and psychiatric disorders (e.g., schizophrenia, mood disorders, attention-deficit/hyperactivity disorder [ADHD]).
Specific referral questions may differ based on the setting in which an individual is seen. In the inpatient setting, typical questions involve issues related to an individual’s current cognitive status and its impact on daily functioning, with an emphasis on identifying what types of services might be appropriate while in the hospital as well as in the community as a crucial part of discharge planning. In acute care hospital settings, individuals who have neurological disorders or who have recently had neurosurgical intervention may be referred to a neuropsychologist for evaluation. Inpatient psychiatric referrals are also common. Inpatient teams often have questions regarding individuals’ safety (i.e., Can they be left alone in their home?), functional independence (i.e., Are they able to live alone? Can they manage their own money?), and employability (i.e., Can they work? In what type of job would they be most likely to succeed?). Results of the evaluation form part of the repertoire of data used by the inpatient team to address these issues, and these evaluation results can provide insights into what supports might be needed to provide the least restrictive environment for the patient and/or what accommodations can be made to maximize his or her success (e.g., in the workplace).
In subacute inpatient settings, referrals may be made to help address issues related to recovery from an injury or psychiatric episode or to help determine if there has been cognitive improvement as a result of medication or other treatment interventions. Data can be used as part of the determination of disability. There are also various forensic and other legal purposes for which neuropsychological data can serve an important purpose in this population, such as contributing to the determination of decision-making capacity (Moberg and Kniele 2006). Results of the neuropsychological evaluation may result in referrals to other specialists, such as cognitive rehabilitation professionals, neurologists, vocational counselors, and educational services, to further inform differential diagnosis and/or make sure any potentially treatable problems are addressed. Finally, the recommendations of the neuropsychologist regarding appropriate compensatory strategies as well as environmental and other modifications are made. Feedback can be provided to the patient, his or her family, the inpatient providers, and community support services, including outpatient providers. This team approach is very common in inpatient settings and allows input from several sources (e.g., physician, neuropsychologist, occupational therapist, other rehabilitation staff) in developing the most efficacious treatment plan.
Neuropsychological evaluations in outpatient settings may be used to support or clarify a diagnosis, to aid in differential diagnosis (especially when there are unusual symptoms or concerns regarding comorbidities), and/or to provide a profile of cognitive strengths and weaknesses to guide rehabilitation, educational, vocational, or other services. Such an evaluation can document changes in functioning since prior evaluation(s), address questions of decline over time, and note the efficacy of treatment. Even in outpatient settings, the interdisciplinary team model can be effective, with input provided by various health care professionals to fully assess an individual, aid in differential diagnosis, and maximize treatment planning. Similarly, neuropsychologists can be integrated into specialty clinics working with various populations (e.g., clinics for geriatric populations, clinics for persons with TBI or developmental disabilities).
Other outpatient models include neuropsychology private practice. In this case, the neuropsychologist receives referrals from various physicians and neuropsychiatrists, performs a patient assessment, and sends a report back to the referral source. In this model, there is less interdisciplinary collaboration; there is a clearer separation between the evaluation provided by the neuropsychologist and the treatment provided by the physician. Finally, there are neuropsychologists who develop forensic practices, in which their primary focus involves the application of neuropsychological assessment methods to the evaluation of criminal or civil litigants. The approach and battery of tests used should be capable of meeting legal standards, and there is often an increased emphasis on collateral sources of information, assessment of response bias, consideration of the individual’s level of effort, and/or issues of malingering.
Regardless of the setting or the model, the type of referral questions may vary somewhat depending on the situation. For example, in the case of an individual with TBI, a neuropsychological evaluation might be used both to provide evidence of brain dysfunction and to describe the nature and severity of problems. A person who has sustained a blow to the head from an automobile accident that produces a brief loss of consciousness, even with no apparent further neurological complications, might experience disruption in cognitive efficiency. On returning to work after 1 week, this individual might be unable to keep up with job demands. After several weeks of on-the-job difficulties, the individual’s physician may refer the him or her to a neuropsychologist. The neuropsychologist might look for evidence of problems with divided attention, sustained concentration and mental tracking, and memory, all of which are common findings in the weeks or months following mild head injury. The neuropsychologist can advise the patient that these problems frequently occur after head injury and that considerable improvement might be expected during the next month or two. Recommendations about how to structure work activities to minimize both these difficulties and the equally common problem of fatigue provide both aid and comfort to the concerned patient.
The most common referral for neuropsychological evaluation of older adults without obvious risk factors for brain disease, other than age, is for early detection of progressive dementias such as Alzheimer’s disease. Most persons have symptoms associated with dementia for at least a year before they see a physician because the problems initially are mild and easily attributed to factors such as aging, concurrent illness, or emotional stress. The progression of symptoms is insidious, especially because many patients have “good” and “bad” days during the early stages of a dementing disorder. Neuropsychological assessment is useful in evaluating whether problems are age-related, attributable to factors such as depression, or suggestive of early dementia.
One of the greatest challenges for a neuropsychologist is to determine whether patients with psychiatric illness show evidence of a separate underlying brain disorder. Many psychiatric patients without neurological disease have cognitive disruptions, as well as behavioral or emotional disturbances. Cognitive impairment is highly prevalent in schizophrenia, particularly with respect to attention, processing speed, memory, and executive function. Patients with unipolar depression (Lee et al. 2012) or bipolar disorder (Mann-Wrobel et al. 2011) may have difficulty with attention, memory, and executive function even when euthymic. Conversely, patients with neurological diseases can present with prominent psychiatric features. Confabulations associated with undiagnosed neurological illnesses, such as Korsakoff’s syndrome, may be misinterpreted as a psychotic illness. Hallucinations may be an early feature of Lewy body dementia and may occur with Parkinson’s disease, Alzheimer’s disease, other neurodegenerative diseases, stroke, epilepsy, migraine, and toxic metabolic encephalopathies.
Many medical conditions can affect brain function, including systemic illnesses such as endocrinopathies; metabolic and electrolyte disturbances associated with diseases of the kidney, liver, and pancreas; and nutritional deficiencies. Vascular disorders, cardiac and pulmonary diseases, anemia, and complications of anesthesia or surgery can compromise blood supply to the brain and thus disrupt cognition.
Age and health habits also must be taken into consideration when evaluating a person’s behavioral alterations because they affect the probability of cerebral disorder (Perfect and Maylor 2000). In addition, certain medications can disrupt cognitive functioning. Such considerations demonstrate the importance of the multifaceted nature of training in neuropsychology, including a knowledge base in psychology, psychiatry, and neurology, among other disciplines.
In cases with no known explanation for mental deterioration, it becomes important to search for possible risk factors or other reasons for brain disease through history taking, physical examination, laboratory tests, and interviews with the patient’s family or close associates. Should this search produce no basis for the mental deterioration, a neuropsychological evaluation can be useful. The neuropsychological evaluation of persons with or without known risk factors for brain damage is diagnostically useful if it identifies cognitive or behavioral deficits, particularly if those deficits occur in a meaningful pattern. A pattern is considered meaningful when it is specific to one or only a few diagnoses (e.g., a pattern suggestive of a lateralized or focal brain disruption).
Neuropsychological signs and symptoms that are possible indicators of a brain disorder are presented in Table 3–1. Confidence in diagnoses based on neuropsychological evidence is greater when risk factors for brain dysfunction exist or the patient shows signs and symptoms of brain dysfunction than when neuropsychological diagnoses rely solely on exclusion of other diagnoses.
Functional class |
Symptoms and signs |
Speech and language |
Dysarthria |
Dysfluency |
|
Marked change in amount of speech output |
|
Paraphasia |
|
Word-finding problems |
|
Academic skills |
Alterations in reading, writing, calculating, and number abilities |
Frequent letter or number reversals |
|
Thinking |
Perseveration of speech |
Simplified or confused mental tracking, reasoning, and concept formation |
|
Motor |
Weakness or clumsiness, particularly if lateralized |
Impaired fine-motor coordination (e.g., changes in handwriting) |
|
Apraxia |
|
Perseveration of action components |
|
Memory |
Impaired recent memory for verbal and/or visuospatial material |
Disorientation |
|
Perception |
Diplopia or visual field alterations |
Inattention (usually left-sided) |
|
Somatosensory alterations (particularly if lateralized) |
|
Inability to recognize familiar stimuli (agnosia) |
|
Visuospatial abilities |
Diminished ability to perform manual skills (e.g., mechanical repairs, sewing) |
Spatial disorientation |
|
Left-right disorientation |
|
Impaired spatial judgment (e.g., angulation of distances) |
|
Emotions |
Diminished emotional control with temper outburst and antisocial behavior |
Diminished empathy or interest in interpersonal relationships |
|
Affective changes |
|
Irritability without evident precipitating factors |
|
Personality change |
|
Social behavior |
Altered appetites and appetitive activities |
(comportment) |
Altered grooming habits (excessive fastidiousness or carelessness) |
Hyperactivity or hypoactivity |
|
Social inappropriateness |
Although neuropsychological assessment provides a measure of the type and degree of cognitive disorder, it often cannot specify the cause of the disturbance. Cognitive deficits appearing in an adult patient who previously functioned well and had no history of psychiatric illness or recent stress should raise suspicions of a neurological disorder.
The referring neuropsychiatrist identifies patients who might benefit from a neuropsychological evaluation, prepares the patient, and formulates referral questions that best define the needed information. A valid evaluation depends on obtaining the patient’s best performance. It is nearly impossible to obtain satisfactory evaluations of patients who are uncooperative, unmotivated, severely fatigued, actively psychotic, seriously depressed, highly anxious, or physically uncomfortable or who want to demonstrate impaired performance for secondary gain. For example, seriously depressed patients may appear to have dementia, and the evaluation may underestimate the individual’s full potential (Yousef et al. 1998). Whenever possible, patients with active psychiatric symptoms should be referred after they have shown clinical improvement, so that the findings are more representative of their true ability uncontaminated by reversible emotional or behavioral disturbances.
To obtain the patient’s cooperation and alleviate unnecessary anxiety, the patient should understand the purpose and nature of the evaluation. The explanation usually includes a statement that the evaluation has been requested to assess how the brain is functioning by looking at thinking abilities using paper and pencil and/or computerized tests. In most cases, patients should know that the examiner will look for cognitive and emotional strengths as well as problem areas to obtain information that could assist with differential diagnosis, treatment planning, and development of compensatory strategies.
The more explicit the referral question, the more likely it is that the evaluation will be conducted to ascertain the needed information. The referral should include identifying information about the patient, reasons for the evaluation request, description of the problem to be assessed, and pertinent history. Because the neuropsychological evaluation is designed specifically around the referral question, it behooves the neuropsychiatrist to be as specific as possible about what he or she and the patient are hoping to get from the evaluation. Some referrals seek behavioral descriptions, such as, “Does this individual with multiple sclerosis show evidence of cognitive deficits, and, if so, what are they? Could they interfere with treatment compliance?” Other referral questions may be framed around issues with patient management (i.e., level of functional independence), counseling, and educational or vocational planning.
A comprehensive neuropsychological evaluation has several components. Obtaining relevant background history is a vital building block on which interpretation of the test results is built. Information is obtained in part from a review of pertinent records (e.g., medical, psychiatric, academic) and, as appropriate, consultation with other practitioners involved with the patient’s care.
The clinical interview is another essential way to gain background history, allowing one to elicit the patient’s and relevant collateral’s (e.g., family) concerns with respect to the nature and course of changes in cognitive, sensory, and motor skills; emotional functioning; behavioral or personality changes; and ability to complete basic and instrumental activities of daily life, as well as functioning in academic, employment, and social settings. The interview also affords the opportunity to confirm and update relevant information, including medical, psychiatric, developmental, educational, and occupational history. Furthermore, the interview provides the neuropsychologist with an opportunity to directly observe the patient’s appearance, attention, speech, thought process and content, and motor abilities and to evaluate affect, behavior, orientation, and judgment. The interview can help gauge the patient’s insight into his or her own abilities. Patients with certain conditions, such as Alzheimer’s disease, schizophrenia, and acquired frontal lobe lesions, may demonstrate poor awareness of their problems or minimize their significance (Flashman 2002). In the extreme form, this may result in complete denial of an obvious impairment, such as hemiplegia in a person with right-hemisphere stroke. More often, patients may misattribute their difficulties—for example, a person with dementia attributing his or her memory problems to normal aging or a person with schizophrenia attributing cognitive impairment to psychological stress.
Neuropsychologists use a variety of standardized tests and measures to assess a patient’s functioning. For the majority of these, normative data are used to aid in the interpretation of test results, although qualitative aspects of performance are also highly informative (e.g., how organized is a patient’s copy of a complex figure rather than just the accuracy of the final drawing). The selection of tests typically follows one of three primary approaches. The fixed battery approach uses the same set of tests with every individual, analogous to a physician conducting a standard physical examination on all patients (e.g., Reitan and Wolfson 1985). This approach usually entails several hours of testing but ensures that all patients complete a fairly broad-based examination. The fixed battery approach has several limitations, however, including risk of failure to focus on specific areas of difficulty for a given patient; it may overlook subtler problems, may not cover all areas relevant to either a reliable diagnosis or practical counseling, and may not resolve uncertainty about why performance is impaired without additional testing. In contrast, the hypothesis-testing approach tailors the neuropsychological evaluation to the patient’s requirements, allowing the examiner to learn what is needed, with greater time and cost efficiency (Bauer 2000). Hypotheses are generated about the source(s) and nature of the brain dysfunction based on background history and behavioral observations, and tests are selected to address each hypothesis. Furthermore, hypothesis testing is considered a dynamic process that continues throughout the assessment, with results from a particular test or set of tests potentially leading to new hypotheses being formulated and prior ones being modified or refuted. For example, an elderly patient may be referred to inform a differential diagnosis of depression versus dementia, based on family reports of forgetfulness and lack of motivation. Competing hypotheses can be tested to determine if changes are due to depression, dementia, or a combination of the two. The examiner may therefore include tests that are relatively unstructured and require active initiation and organization, and he or she may look at whether cuing and recognition memory testing aid in retrieval of information from memory. Finally, most neuropsychologists use a fixed-flexible approach (Bauer 2000) in which the examiner starts the evaluation with a preferred core set of measures that have demonstrated applicability to a variety of clinical populations and usefulness for answering a wide range of clinical questions. This core is then supplemented with other measures based on a hypothesis-testing approach.
Clinical neuropsychological evaluations typically go beyond assessing cognitive functioning; they commonly include measures of emotional functioning and questionnaires assessing personality and a variety of other symptoms, depending on the presenting complaints and diagnosis at hand (e.g., fatigue and pain rating scales). This is important regardless of diagnosis because mood, personality, and other symptoms can impact test performance, as has been seen in numerous neurological populations (e.g., Butterfield et al. 2010), and these factors may be important contributors to the patient’s clinical presentation.
Most tests of cognitive ability are designed with the expectation that very few will obtain a perfect score and that most scores will cluster in a middle range. The scores of many persons taking the test can be plotted as a distribution curve. Most scores on tests of complex learned behaviors fall into a characteristic bell-shaped curve called a normal distribution curve. The statistical descriptors of the curve are the mean, or average score; the degree of spread of scores about the mean, expressed as the standard deviation; and the range, or the distance from the highest to the lowest scores. Most neuropsychological measures are designed so that all individuals within a culture are expected to be able to perform the tasks; thus, failure to do so may be suggestive of impairment.
The level of competence within different cognitive domains varies from individual to individual and also varies within the same individual at different times. This variability also has the characteristics of a normal curve. Because of the normal variability of performance on cognitive tests, any single score should be interpreted as falling within a range and should not be taken as a precise value. For this reason, many neuropsychologists are reluctant to report exact scores; rather, they describe their findings in terms of ability levels (e.g., average range, mildly impaired range). See Table 3–2 for interpretations of ability levels expressed as deviations from the mean of the normative sample. An individual’s score is compared with normative data, often through calculation of a standard or z score, which describes the individual’s performance in terms of statistically regular distances (i.e., standard deviations) from the mean relative to individuals of similar age, gender, and/or educational level. For example, a performance in the below-average direction that is greater than two standard deviations from the mean is usually described as falling in the impaired range because 98% of the normative sample taking the test achieve better scores.
z Score |
Percentile rank |
Descriptor |
2.0 and above |
98 and above |
Very superior |
1.3 to 1.99 |
91 to 97 |
Superior |
0.66 to 1.29 |
75 to 90 |
High average |
–0.069 to 0.065 |
25 to 74 |
Average |
–1.39 to –0.7 |
10 to 24 |
Low average |
–2.09 to –1.4 |
2 to 9 |
Borderline |
–2.1 and below |
1.9 and below |
Extremely lowa |
–2.69 to –2.1 |
0.38 to 1.89 |
Mildly impaired |
–3.09 to –2.7 |
0.13 to 0.37 |
Moderately impaired |
–3.1 and below |
0.12 and below |
Severely impaired |
Note. The respective cutoff values are expressed as z scores, along with their percentile equivalents.
aThe extremely low range encompasses the mildly, moderately, and severely impaired range performances.
Psychological tests should be constructed to satisfy both reliability and validity criteria (American Educational Research Association et al. 2014). The reliability of a test refers to the consistency of test scores when the test is given to the same individual at different times or with different sets of equivalent items. Tests have validity when they measure what they purport to measure. For example, if a test is designed to measure attention, then patient groups known to have attention deficits should perform more poorly on the test than persons from the population at large. To achieve reliability and validity, tests are often constructed with large normative samples composed of individuals with similar demographic characteristics, such as age and education. For example, the Wechsler Adult Intelligence Scale–IV (WAIS-IV; Wechsler 2008) has normative data for 2,220 adults stratified by sex, race/ethnicity, geographic region, and education.
Some neuropsychological tests detect subtle deficits better than others; however, other factors such as depression, anxiety, medicine side effects, and low energy level due to systemic illness also may disrupt performance on these tests. Therefore, they are sensitive to cognitive disruption but not specific to one type of cognitive disturbance. The specificity of a test in detecting a disorder depends on the overlap between the distributions of the scores for persons who do not have and persons who have the disorder. In general, the less overlap there is, the better the test can differentiate between normal and abnormal performances. A test that is highly specific purports to measure a defined cognitive construct and produces few false positive findings. Many neuropsychological tests offer a trade-off between sensitivity and specificity, and detailed information regarding many tests can be found in books such as A Compendium of Neuropsychological Tests (Strauss et al. 2006).
Neuropsychological assessment relies on comparisons between the patient’s test performance and normative data, as well as intra-individual comparison of the patient’s current level of functioning versus his or her known or estimated level of premorbid functioning. Most healthy people perform within a statistically definable range on cognitive tests, determined by normative data that typically take into account demographic variables, and deviations below this expected range raise the question of impairment. Impairment may also be identified as a discrepancy between current test performance and scores on estimates of premorbid functioning. Such estimates typically involve mathematically based formulas that use demographic information or performance on tests of functions less likely to be affected by brain disorders, for example, fund of information or reading vocabulary tests such as the Test of Premorbid Functioning from the Advanced Clinical Solutions (Wechsler 2009) and the Reading subtest from the Wide Range Achievement Test (Wilkinson and Robertson 2006).
The assumption of impairment is valid in most instances in which one or a set of scores fall significantly below expectations, although even in healthy individuals, impairment may be seen on one or a few scores across an extensive battery of measures (Schretlen et al. 2008). Impairment on multiple measures involving similar or related abilities increases the examiner’s confidence in the findings. If similar tasks do not elicit impairment, either the finding was spurious or the tasks varied in important features that did not involve the patient’s problem area.
For meaningful interpretations of neuropsychological functioning, examiners not only rely on tests but also search for a performance pattern that makes neuropsychological sense using test scores and qualitative features of performance. Because there are few pathognomonic findings in neuropsychology (or in most other branches of medical science), the pattern of performance may suggest several diagnoses but could also facilitate differential diagnosis. For example, a cluster of mild impairments in processing speed, concentration, and memory is a nonspecific finding associated with several conditions, including mild TBI and depression. Other patterns may be highly specific for certain conditions. The finding of left-sided neglect and visuospatial distortions is highly suggestive of brain dysfunction and specifically occurs with right hemisphere damage. For many neuropsychological conditions, typical deficit patterns are known, allowing the examiner to evaluate the patient’s performances in light of these known patterns.
The quality of a neuropsychological evaluation depends on many factors. In general, one should beware of conclusions from evaluations in which test scores alone (i.e., without information from the history, interview, observations of examination behavior) are used to make diagnostic decisions and of dogmatic statements offered without strong supportive evidence. It is also important to remember that neuropsychological tests do not measure “brain damage.” Rather, the finding of impaired functioning implies an underlying brain disorder; however, other possible interpretations may exist that should be addressed in the evaluation (e.g., mood). Furthermore, neuropsychological evaluations increasingly include stand-alone and/or embedded measures of test-taking effort and provide evidence about whether the assessment results should be considered as a valid reflection of the patient’s current level of functioning. While it is very difficult to clearly establish that a patient has malingered on testing or to determine the reason(s) for failure on measures of test-taking effort, one must be mindful of the validity of test findings.
In this section, we present a selective review of tests used for assessment of areas of cognition and personality. Many useful neuropsychological tests are not described in this summary. Please refer to texts such as Neuropsychological Assessment (Lezak et al. 2012) and A Compendium of Neuropsychological Tests (Strauss et al. 2006) for more detailed information on other frequently used tests.
Attentional deficits and slowed processing speed are common features of many disorders, for example, depression, schizophrenia, and Parkinson’s disease. Several relevant measures of attention and processing speed ability are included in the WAIS-IV (Wechsler 2008). For example, the Digit Span subtest is included in the Working Memory Index (WMI). Immediate auditory attention is assessed using Digit Span forward, which involves repetition of digits in the order presented and has minimal working memory demand. Processing speed is measured in the WAIS-IV and has its own designated index, the Processing Speed Index (PSI). Digit Symbol Coding is a task of visual attention, processing speed, and psychomotor speed and requires integration of each to complete the task successfully. Similarly, the Symbol Search subtest is a measure of attention, processing speed, psychomotor speed, and visual pattern discrimination. These tests, like many processing speed measures, are susceptible to the effects of extraneous factors, such as motor slowing, which could be due to peripheral factors such as nerve or muscle damage, as well as to diminished visual acuity.
There are a variety of other measures of attention and processing speed that differ in difficulty and processing demands, and these measures can be incorporated into the assessment based on the specific referral question or functional concern. Measures of sustained auditory and visual attention are presumably more difficult because of the increased cognitive demand required to focus on relevant stimuli, while suppressing responding to irrelevant stimuli, for a prolonged period of time. Many neuropsychological batteries will include sustained attention tasks when diagnostic clarification is requested for neurodevelopmental disorders related to attention, such as ADHD. While neuropsychological assessment is not required to make a diagnosis of ADHD, neuropsychological measures provide objective data regarding the nature and extent of associated cognitive problems. Sustained visual attention measures, such as the Conners’ Continuous Performance Test (Conners 2004), provide information regarding inattention, impulsivity, and psychomotor speed and its consistency, as well as an individual’s response style (e.g., emphasis on accuracy vs. speed). The Trail Making Test (TMT; Reitan and Wolfson 1985) is a measure of visual attention, and it relies heavily on intact psychomotor processing speed, cognitive flexibility, and visual scanning abilities. The TMT is divided into parts A and B. Part A requires the individual to connect a sequence of numbers in ascending order and purports to measure processing speed, visual attention, and visual scanning. Part B requires the individual to sequence numbers and letters in an ascending, alternating order and incorporates a cognitive flexibility component to the aforementioned abilities. This test has been widely used to detect brain damage, with longer completion time and/or more errors being indicative of impairment.
Memory is frequently reported as the primary cognitive concern by individuals seeking assessment. Memory may be divided into two major subdomains. Implicit (or procedural) memory refers to information that is automatized and thus typically not consciously retrieved (e.g., buttoning a shirt, driving a car) and is not typically assessed during the neuropsychological evaluation. Explicit (or declarative) memory refers to information that is consciously retrieved from previous experience. Furthermore, short-term memory involves information that is held for a brief period of time (typically 30 seconds or less), while long-term memory involves the retention of information for minutes, days, or even years. Long-term memory can be divided into semantic memory and episodic memory. Semantic (fact) memory refers to general knowledge about the world that we learn throughout our lives, but it is not linked to a specific time, person, or place. It is distinct from episodic memory, which is our memory of specific events and experiences. For instance, semantic memory might contain information about what a cat is, whereas episodic memory might contain a specific memory of petting a particular cat. Semantic memory may be assessed using the WAIS-IV Vocabulary and Information subtests (Wechsler 2008), as well as other tests such as category fluency (e.g., name all the animals one can think of in a minute) and confrontation naming (i.e., object naming).
Memory can be thought of as involving three stages: encoding, consolidation, and retrieval. Encoding, also referred to as learning or acquisition, involves the process of acquiring new information. Consolidation of information occurs when recently encoded information is manipulated and stored in a meaningful way for increased accuracy during later recall. Retrieval is the expressed recall of information that has been successfully encoded and consolidated. All three episodic memory subprocesses provide valuable information about the overall learning and memory abilities of a patient, and this often guides the recommendations provided by neuropsychologists. For example, if an encoding difficulty is observed, a neuropsychologist may recommend that physicians and staff working with the patient repeat information, write information down, and incorporate the use of organization strategies to enhance encoding and later recall.
The type of information presented in memory tests can vary significantly. For example, verbal memory tests may use contextual (e.g., information presented in a story) or noncontextual (e.g., information presented in a seemingly random word list) formats. Similarly, visual information can be simple (e.g., basic geometric figures) or more complex (e.g., geometrically detailed and unnameable figures). A number of neuropsychological tests measure these aspects of memory. The Wechsler Memory Scale—4th Edition (Jorge et al. 2010) includes subtests assessing memory for different types of information (e.g., story recall, word pairs, designs). The California Verbal Learning Test–II provides valuable insight into auditory-verbal noncontextual memory using a word-list format (Delis et al. 2000). Measures of simple visual memory include the Brief Visuospatial Memory Test (Benedict 1997), which uses an array of simple geometric figures to measure visual learning and memory; a more complex measure is the Rey Complex Figure Test (Meyers and Meyers 1995). These tests, as well as many others, contain a similar structure, with information presented during a single learning trial or over the course of several learning trials. Depending on the measure, request to recall the presented information can be immediate, after a brief delay (typically less than 5 minutes), or after a longer delay (usually 20–30 minutes). Recognition memory is a key component of many memory measures and requires the individual to discriminate between stimuli that were and were not previously presented to them using a “yes” or “no” response format; this helps determine whether memory deficits are related to retrieval or consolidation of information.
Evaluating language is an essential component of the neuropsychological evaluation. Receptive language refers to the ability to comprehend the symbolic communication of others. In contrast, expressive language refers to the ability to produce meaningful and coherent symbolic communication. A comprehensive neuropsychological battery should include measures of both receptive and expressive language, because these abilities often frame the context in which results may be interpreted. For example, an individual with impaired receptive language may demonstrate a range of poor performances on cognitive measures as a result of not adequately understanding task instructions.
Typical neuropsychological evaluations include a few measures of language abilities such as confrontation naming (e.g., Boston Naming Test, 2nd edition; Kaplan et al. 2001) and verbal fluency (phonemic and semantic), which are sensitive to disruptions in systems involved in language, especially involving the frontal and temporal lobes. In certain circumstances, however, a more comprehensive language assessment may be required to diagnose and characterize language disorders, called aphasias. Aphasias can involve language comprehension (receptive aphasia), expressive language (expressive aphasia), repetition (conduction aphasia), confrontation naming ability (anomic aphasia), and/or prosody, depending on the location of the injury. The Boston Diagnostic Aphasia Examination (Goodglass et al. 2001) and Multilingual Aphasia Examination (Benton et al. 1994), for example, may aid in differential diagnosis and treatment planning because of their wide scope and sensitivity to different aphasias. Such batteries typically include measures of spontaneous speech, speech comprehension, word and sentence repetition, confrontation naming, reading, and writing.
Deficits in visuospatial abilities can manifest as perceptual distortions and/or impairments in object or facial recognition, mental rotation, spatial memory, navigation and spatial orientation, visual neglect, and representation of the size of and distance between objects. The most commonly used measures to assess visuospatial functioning involve visual discrimination (e.g., geometric forms, angulation, faces, familiar objects) or the ability to integrate fragmented, disarranged pieces into an identifiable whole object. Additionally, spatial localization and visuoperception are integral components of some widely administered measures, such as the Clock Drawing Test, which requires correctly drawing a clock face (i.e., shape and contour), placement and arrangement of the numbers, and placement of and discrimination (i.e., size differentiation) between the hour and minute hands. Notably, many tests of visuospatial abilities also require visuoconstruction ability, such as drawing or manually manipulating blocks. Thus, additional testing may be needed to determine whether a patient has a purely visuospatial impairment or whether impairment is the result of difficulties with construction. For example, a patient with Parkinson’s disease may show impairment on a test involving replicating a design using blocks (e.g., WAIS-IV Block Design; Wechsler 2008), but this may be due to poor construction secondary to motor slowing. Use of similar tests that do not require a motor response could be informative in such cases.
Processing of visuospatial information involves multiple brain systems, although typically posterior areas of the right hemisphere are involved. For example, identification of visuospatial information is heavily reliant on intact right posterior temporal systems (the “what” visual stream), whereas localization of visual information is dependent on intact right posterior parietal systems (the “where” visual stream) (Farah 2003).
Motor abilities may be impaired in patients with a variety of conditions that often prompt referral for neuropsychological evaluation (e.g., Parkinson’s disease, multiple sclerosis). Commonly employed measures, such as the Finger Tapping Test (Reitan and Wolfson 1985), Grooved Pegboard (Reitan and Wolfson 1985), and the Purdue Pegboard (Tiffin and Asher 1948), assess manual motor speed and, to varying degrees, manual motor dexterity and coordination. A hand dynamometer is often used to gauge grip strength. Assessment of performance separately for each hand, as well as discrepancies between scores obtained for a patient’s dominant and nondominant hand, can provide valuable information with respect to the possibility of a lateralized deficit (i.e., left or right hemisphere), especially if the results are consistent with other aspects of the assessment (e.g., discrepancy between verbal and perceptual intellectual skills).
Apraxia, a type of motor impairment, is an inability to perform a desired sequence of motor activities that is not a direct result of motor weakness or paralysis. Rather, the primary deficit is in planning and carrying out the required activities, and it is associated with disruption of spatial location and the appropriate hand gestures for completing actions (Haaland et al. 1999). Tests for apraxia assess the patient’s ability to reproduce learned movements of the face or limbs and may include, for instance, the use of objects (e.g., pantomiming the use of an object), conventional gestures (e.g., waving good-bye), and buccofacial and respiratory responses (e.g., pretending to blow out a candle). Assessment of praxis can provide valuable information with regard to the cerebral lateralization of abnormality based on the side of the apraxia (left- or right-side motor skills), as well as to more specific brain regions based on the nature of the apraxia (e.g., ideational).
Executive function is a category of cognition that comprises interrelated self-regulatory control processes involved in the selection, initiation, organization, execution, and monitoring of goal-directed behavior (Roth et al. 2005; Stuss and Alexander 2000). Executive function includes the ability to independently initiate behaviors, inhibit impulses, select relevant task goals, plan and organize a means to solve problems (especially when novel or complex), think flexibly in response to changing circumstances, regulate emotions, monitor and evaluate one’s behavior, and hold information actively “online” (i.e., working memory) so that the information may be manipulated and utilized in the service of planning and guiding cognition and behavior. Accordingly, executive function is essential for the highest levels of cognition such as judgment, decision making, and self-awareness.
There are numerous tests designed to assess executive function, and these vary widely in terms of the specific abilities required. Working memory is most commonly assessed using span tasks such as Digit Span Backward from the WAIS-IV, involving repeating digits in reverse order. The Paced Auditory Serial Addition Test places greater demand on working memory and processing speed, lasting several minutes and requiring an individual to add consecutive pairs of numbers presented at a fixed rate (e.g., a 3-second interval), with increased difficulty achieved by presenting numbers at an increased rate (e.g., a 2-second interval) (Gronwall 1977). The standard Stroop Color-Word Interference Test (Golden 1978) presents color words in incongruent colors (e.g., the word red written in blue ink) and requires the individual to suppress the habitual tendency to read words rather than say colors. Verbal fluency tests (described in the subsection “Language”) may be used to measure initiation of concepts, task persistence, and ability to think flexibly.
Patients with frontal lobe or diffuse brain injuries often have difficulty with relatively open-ended tests that permit them to decide how to perform the task, all the while receiving minimal instruction or feedback. Tests such as the Wisconsin Card Sorting Test (WCST; Heaton et al. 1993) and the Delis-Kaplan Executive Function System (D-KEFS) Sorting Test (Delis et al. 2001) require several abilities, including concept formation, hypothesis testing, problem solving, flexibility of thinking, and working memory. For example, the WCST requires the patient to deduce the principles by which to sort a deck of cards (i.e., to generate an understanding of the pattern/category), but without warning the patient, the examiner changes the correct principle as the test proceeds. Therefore, the patient must figure out independently that a shift in principles has occurred and change his or her behavior accordingly (i.e., to avoid perseverating on the prior pattern/category). As noted in the subsection “Attention and Processing Speed,” Part B of the TMT is also commonly used to assess a patient’s ability to think flexibly. Tests of planning and foresight, such as the Tower of London (e.g., Shallice 1982), require the person to move disks from stack to stack to match the examiner’s configuration of disks but following certain rules (e.g., no larger disk placed on top of a smaller disk, move only disk at a time).
Most performance-based tests of executive function are limited, however, as they do not tap the integrated, multidimensional, relativistic, priority-based decision making that is often demanded in real-world situations (Goldberg and Podell 2000). Thus, some patients reported to have executive dysfunction in their everyday lives may perform well on tests because the examiner provides the structure, organization, and monitoring necessary for an individual’s optimal performance (Kaplan 1988). This has led to the development of tests that try to enhance ecological validity by using real-world scenarios and problems, such as the Behavioral Assessment of the Dysexecutive Syndrome (Wilson et al. 1996), and standardized rating scales of executive function as manifested in everyday life, such as the Behavior Rating Inventory of Executive Function (Roth et al. 2005) and the Frontal Systems Behavior Scale (Grace and Malloy 2002).
Executive dysfunction has been reported in patients with a wide variety of neurological and neuropsychiatric disorders, and executive dysfunction contributes to difficulties maintaining socially appropriate conduct, as well as successful academic and occupational functioning. The presence of executive dysfunction can be helpful in differential diagnosis in some situations, such as differentiating mild Alzheimer’s disease from frontotemporal dementia; the latter is generally associated with more prominent impairment. It should be noted, however, that whereas executive function has historically been most closely associated with the frontal lobes, there is a plethora of evidence indicating involvement of wide neural networks, including both cortical (frontal, parietal, and temporal lobes) and subcortical (e.g., basal ganglia, cerebellum) regions. Indeed, patients with focal lesions in nonfrontal brain regions may also present with executive dysfunction, and thus poor performance on measures of executive function does not necessarily imply frontal lobe damage.
As noted in the section “Interpretation: Principles and Cautions,” inclusion of stand-alone and/or embedded measures of test-taking effort, also called performance validity tests (PVTs), has become a standard of practice in neuropsychological evaluations, especially when issues such as litigation and disability claims are involved (Bush et al. 2005). The basic premise of most PVTs is that they are designed to appear cognitively challenging, but in actuality, PVTs pose little difficulty for healthy individuals as well as the vast majority of patients with clinical conditions such as TBI, depression, or mild dementia.
Stand-alone PVTs most commonly involve a memory testing format such as the Test of Memory Malingering (Tombaugh 1997), the Word Memory Test (Green 2003), and the Rey 15-Item Test (Goldberg and Miller 1986). Embedded performance validity measures have been identified for numerous tests, such as reliable digit span using the WAIS-IV Digit Span subtest, allowing the examiner to gauge effort without adding additional time to the test session. A combination of stand-alone and embedded PVTs is generally preferred.
Intellectual functioning, often expressed as the intelligence quotient (IQ), provides a context in which neuropsychological results may be interpreted. The most commonly used measure of intellectual ability in adults is the WAIS-IV (Wechsler 2008). It is composed of tests of crystallized intelligence (e.g., academic-based knowledge that is characteristically stable) as assessed through the Verbal Comprehension Index (VCI) and Perceptual Reasoning Index (PRI), as well as tests of fluid intelligence (e.g., constructs that can vary across time, day, and situation), as measured by the WMI and the PSI. The individual tests within each index were designed to assess relatively distinct areas of cognition, such as mental arithmetic, nonverbal abstract reasoning, and visuospatial organization, and thus are differentially sensitive to identifying dysfunction within various areas of the brain.
Specific information regarding the WAIS-IV indices, including the subtests that compose them, can be found in the WAIS-IV manual (Wechsler 2008). Each index of the WAIS-IV is composed of subtest scores (e.g., the PRI contains the Block Design, Matrix Reasoning, and Visual Puzzles subtests), and each of these subtest scores contributes to the overall index score. Significant differences among the subtest scores within an index (i.e., differences greater than 1.5 standard deviations) may result in IQ scores and/or ability levels that may not accurately represent overall ability. For example, a patient with a visuospatial deficit may have difficulty performing only the Block Design test, which is averaged with the other PRI subtests, and may produce a PRI score that does not reflect his or her true overall perceptual reasoning abilities. Therefore, neuropsychologists give consideration to both the index score and the individual subtest scores.
The overall index scores, as well as the subtests that make up each index, provide a wealth of information regarding cognitive and intellectual strengths and weaknesses, in addition to potential neuroanatomical implications of dysfunction. For example, discrepancies between overall VCI and PRI scores can indicate whether an individual has a particular proficiency for verbal or perceptual reasoning abilities (i.e., greater left or right hemisphere functioning, respectively).
It is important to note that many intellectual assessments, such as the WAIS-IV, require intact auditory and verbal functioning. Nonverbal measures of intellectual functioning are available for those with primary difficulties in these areas (e.g., Test of Nonverbal Intelligence; Brown et al. 2010).
Formal assessment of emotional status is usually included in neuropsychological batteries, as mood can impact an individual’s actual and/or perceived cognitive abilities. In addition to information obtained via the clinical interview, patients are asked to complete standardized self-report mood rating scales. For example, the Beck Depression Inventory (Beck et al. 1996) is a commonly used self-report measure of depressive symptoms experienced during the past 2 weeks. A quantitative value is assigned to each response (i.e., 0–4) for each item, which is summed to produce a total score. A total score range of 0–13 indicates minimal symptoms; 14–19, mild symptoms; 20–28, moderate symptoms; and over 29, severe symptoms.
Personality assessment is often included in the neuropsychological evaluation to further characterize the patient’s psychological, behavioral, emotional, and social functioning. Commonly used self-report measures in adults include the Minnesota Multiphasic Personality Inventory, 2nd Edition (MMPI-2; Butcher et al. 1989), and the Personality Assessment Inventory (Morey 1991). Both of these measures include validity scales, allowing the clinician to gauge the veracity of the patient’s responses (i.e., exaggeration, minimization, inconsistency across items of similar content), as well as a numerous clinical scales and subscales reflecting various aspects of functioning. Examination of both individual scales and the pattern of elevations among the scales (higher scores reflecting greater endorsement of a problem area) contribute to clinical interpretation. Many variations in patterns of elevations exist (referred to as code types), and their interpretation may differ depending on the population assessed. For example, elevations on the MMPI-2 Hs (Hypochondriasis), D (Depression), and Sc (Schizophrenia) scales are common because many neuropsychiatric disorders are associated with symptoms reflected within these scales (LaChapelle and Alfano 2005). Information regarding these scales and their interpretations is available in the MMPI-2 manual (Butcher et al. 1989).
Administration of these self-report measures is simple, and most can be completed within 10 minutes. Personality assessments are often lengthier, as is the case with the MMPI-2, which takes approximately 60–90 minutes to complete. Nonetheless, such measures can provide important insights into the patient’s functioning and thereby contribute to differential diagnosis and treatment planning.
The use of computerized neuropsychological test batteries has been gradually increasing, although considerably more in research than in clinical contexts. There are numerous computerized test batteries available, which vary widely with respect to the specific domains of functioning assessed and measures employed, how the measures are implemented (e.g., instructions, stimuli, response requirements), and their psychometric properties (e.g., Cook et al. 2009). Advantages of computerized testing include test data obtained under highly standardized conditions, ease of acquiring precise data on accuracy and speed of responses, and minimal time expenditure by the examiner. On the other hand, limitations exist that render computerized testing problematic for regular clinical use. In particular, failure to acquire important information about the way an individual approaches a cognitive task or why performance is impaired (e.g., motivation, fatigue, frustration tolerance, use of strategy to complete a task), which is only possible if the examiner observes test performance, can impact the validity of the test results and thus limit interpretability. Furthermore, although people of all ages are increasingly exposed to computers, research indicates that computer-related anxiety and a negative attitude toward computers can affect test performance on computerized neuropsychological measures (Browndyke et al. 2002; Fazeli et al. 2013).
Neuropsychiatrists and physicians are at times faced with patients whose capacity to independently make personal decisions (e.g., legal, financial, medical) is called into question. Because neuropsychologists have extensive training in standardized assessment and interpretation, they can contribute objective data to the determination of decisional capacity. Such evaluations typically include neuropsychological measures used in standard evaluations, but it is recognized that the relationship between individual neuropsychological test scores and decision making is modest at best (Wood and O’Bryan 2011). Thus, neuropsychological evaluations conducted to help inform competency also usually employ one or more additional measures of functional abilities.
Questionnaire measures pertaining to basic (e.g., hygiene, feeding) and instrumental (e.g., managing medications and finances, driving, cooking, cleaning) activities of daily living, completed by the patient and ideally also by a knowledgeable informant, can be informative. There are also semistructured interviews that facilitate acquiring information that is more specific to the nature of the suspected compromised decision-making ability. One example is the Aid to Capacity Evaluation (Etchells et al. 1999), which can help determine the extent to which a patient understands the relevant information and the potential consequences with regard to a specific medical treatment decision. The use of performance-based measures of functional abilities is also recommended for capacity evaluations. For example, the Texas Functional Living Scale (Cullum et al. 2001) has tasks in which the examinee is asked to make change, remember to take medications, tell time, look up and input a telephone number, and use a calendar.
With advances in neuroimaging and other neurodiagnostics, there has been a shift in the focus of neuropsychological assessment from the diagnosis of possible brain damage to a better understanding of specific brain-behavior relations and the psychosocial consequences of brain damage. Patients are referred for neuropsychological assessment for a variety of reasons. In some instances, the patient will have a known brain disorder (e.g., cerebrovascular disorder, developmental disorder, traumatic brain injury, Alzheimer’s disease or related dementing disorder, Parkinson’s disease, multiple sclerosis, Huntington’s disease, tumor, seizures, and psychiatric disorder associated with brain dysfunction). Other times, the referred individual may have a known risk factor for brain disorder; concerns related to potential changes in cognition or behavior might be the result of such a disorder. Furthermore, brain disorder or dysfunction may be suspected when a person’s behavior or personality changes without an identifiable cause. An explanation is sought because behavior patterns and personality are relatively stable characteristics of adults, and these changes require an explanation.
Neuropsychology is a specialty practice focused on the assessment of brain function and brain-behavior relationships. It can be useful in defining the nature and severity of cognitive difficulties, as well as providing information about a patient’s personality characteristics, social behavior, emotional status, and adaptation to their conditions. The potential for independent living and productive activity can also be inferred from these data. Information garnered in the assessment provides a foundation for treatment planning, vocational training, competency determination, and counseling for both patients and their families. Clinical neuropsychologists serve as invaluable clinical experts who integrate information from a person’s history, behavioral observations, and test data to provide a snapshot of current cognitive functioning, help identify factors contributing to dysfunction, and guide treatment and recommendations; they are an integral and unique contributor to the patient’s clinical team.
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