Q1. What happens to memory and thinking as we age?
A1. Beginning in our 30s or 40s, the retrieval of information that we know, especially names and words, becomes more difficult. This ability is sometimes referred to as “free recall memory,” because it is our attempt to report, in words and without clues, knowledge we have stored in our brain. Research has shown that the average 25-year-old can recall between 6 and 7 words from a list of 10 unrelated words read to them several minutes before. The average 75-year-old, in contrast, recalls about 5 words from that list. This means that free recall memory declines as we age, even though the change is not dramatic.
The results are different if you change the experiment. The study starts out the same, giving people a list of 10 words to remember. But rather than ask them to recall as many words as they can after the several-minute delay, the researcher gives them a written list of 20 words, 10 of which are the words they were asked to remember and 10 of which are new words. When asked to circle only the 10 words they were initially asked to remember, the 75-year-olds and the 25-year-olds do equally well. This indicates that the ability to correctly recognize previously encountered information, recognition memory, is not affected by normal aging. The different results from these two studies demonstrate that normal aging is not accompanied by a decline in every type of memory.
In addition, speed of performance, both physical and mental, slows as we age. This means that putting pressure on older people to perform quickly puts them at a disadvantage. If given enough time, older people perform normally on many tests.
Q2. I am having trouble remembering the names of friends and family members and difficulty coming up with the words I want to say. Should I worry?
A2. The definition of dementia requires both a decline in thinking (also called “cognition”) and a decline in the ability to perform everyday activities such as work routines, household activities, and using transportation. If you have not had a decline in daily functioning as a result of cognitive change, then you do not meet criteria for dementia.
Recognition memory, the ability to correctly remember previously encountered information when given a yes-no choice, does not appear to be affected by normal aging.
However, when the symptoms of dementia are first developing, there is a period in which daily functioning is not yet affected. This condition is called “mild cognitive impairment (MCI).” It is defined as a decline in memory or one other cognitive ability (for example, judgement or following directions) of 30% to 45%. At present, testing by a neuropsychologist is the best way to determine if there has been this degree of decline.
Neuropsychologists administer tests that determine what a person’s lifelong abilities have been and tests that measure whether there has been a decline from that level. People who have persistent worries about their memory, who are told by others who know them well that they are repeatedly forgetful or not performing at their usual level, or who believe that their thinking problems are interfering with their daily lives should be tested by an expert. Neuropsychological testing is time consuming and expensive, and is administered by experts who are not available in every community. This is one reason why scientists are trying to identify blood tests or other biological measures (referred to as “biomarkers”) that would identify those who should undergo in-depth testing.
An expert in the assessment of cognition should test a person who
Q3. Are there benefits to the early recognition of mild cognitive impairment (MCI) and dementia?
A3. Most experts believe that early identification of MCI and dementia will encourage people to write a will and designate a durable power of attorney for health (see Q59) if they have not already done so. Early identification might help people begin to make necessary changes in their lives. It might also help loved ones or others close to the person realize that changes they are observing are due to a disease that is impairing thinking, not to purposeful resistance or psychological difficulties. None of these potential benefits has been proven. I have been told by some people that they would want to know as soon as possible if they are developing dementia, but others have said that they would not want to know their diagnosis early unless there were a definitive treatment. In my opinion, universal screening should become the norm only if it improves patient outcomes or if disease-modifying treatments are available.
Q4. I live alone and am concerned about my memory. For a few years I have had intermittent trouble remembering things, but so do my friends. I mentioned this to my primary care doctor on my last visit and she reassured me that there was nothing to worry about. Now I’m worried because I’ve started having trouble doing my checkbook, something I have always done without difficulty, and last year I needed to get help filling out my tax forms, another thing I had always done myself. Should I be evaluated? If so, should I go to a memory specialist?
A4. Word-finding difficulty or occasionally misplacing keys or glasses does become more common as people age (see Q1), but difficulty doing activities that were previously within a person’s capabilities, such as filling out a checkbook, banking online, filing taxes, cooking meals, and being effective at work, does not. I’d suggest you contact your primary care doctor and tell her about your new symptoms. In general, primary care physicians are capable of evaluating people for dementia, but when a person is young (under age 65), has developed difficulty thinking over a period of weeks or months, or has developed signs of neurological disease such as weakness, tremor (shaking), muscle twitching, or numbness in the hands or feet, the person should see a specialist in dementia. I suggest discussing with your primary care doctor whether she can evaluate you or would prefer to refer you to a knowledgeable specialist.