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How dementia affects the way we think

Dementia is the umbrella term for a group of conditions in which the brain deteriorates (see ‘What the science tells us’ if you are interested in the scientific details). In order to plan activities that a person with dementia can do, and help them participate as fully as possible in these activities, we need to understand the types of difficulties with thinking that people with dementia have and then create strategies to compensate for these difficulties.

Here are some of the abilities and characteristics handled by our brain:

Different areas of the brain are responsible for each ability listed above, and all the abilities are affected by dementia.

Difficulties with memory

There are two main types of memory: short-term and long-term. Short-term memory is information that we hold in our brain temporarily so that we can use the information fairly quickly. Examples include the name of a person we have just met at a party, or a telephone number that we want to dial. Most information that we store in our short-term memory we do not keep permanently, as our short-term memory store has a limited size. We can think of short-term memory as a holding room that can only store a maximum of between five and nine items of information. This maximum storage ability is sometimes referred to as ‘seven plus or minus two’. We forget information when it is no longer useful to us, or when it is replaced by new items in our short-term store room.

Information is more permanently stored when it is transferred from our short-term memory to our long-term memory. We can consciously or unconsciously choose for this transfer to happen. An experience, piece of information or skill is more likely to be stored in our long-term memory if we have attended to it well, or practised or rehearsed it, if it is meaningful to us, and if it is associated with strong emotions (either good or bad).

People with dementia usually experience difficulties with their short-term memory first. They do not seem to be able to keep new information in their head for even a short time. This means that it is very difficult for them to form new long-term memories, because if the information doesn’t get into the short-term store in the first place, it can’t then be transferred into long-term storage.

People with dementia still have information in their long-term memory store, though slowly this is lost with the disease. Imagine that the long-term memory system of the brain is a tall, narrow storage box with the opening at the top. Our earliest childhood memories are stored at the bottom of the box and our most recent memories are at the top. As the brain is eroded by dementia, the storage box deteriorates from the top down, so memories that were stored most recently are lost first. The person then sometimes thinks that older memories are actually recent memories of current events and people. This is why people with severe dementia often seem to be living in the past and remember the details of things that happened decades ago very clearly, but can’t remember what they had for lunch today. The person with dementia may also have trouble accessing the information in their long-term store. This is similar to the situation when the internet stops working and we can’t access our files stored online. The information is still there, we just can’t get to it, and later on the system may work again and we can get the information again.

Having missing information from their long-term memory means that people with moderate to severe dementia are often operating in a situation or place they can’t remember. They can’t remember the person, even if they have interacted with them before, and have to figure out who the person is, whether he is trustworthy and how to relate to him. This may be complicated if the stranger seems to know the person with dementia, and the person with dementia might have to pretend to know them in order to be polite. The person with dementia might not remember a place, even if they have been there many times, and will have to figure out where things are located, such as the toilet. Having to figure things out all the time can be very tiring. When we travel or start a new job, most of us find it more mentally tiring than a routine day at work or home, because in these situations we have to process so much more new information relating to people and places.

We usually think of memory as retrospective, or relating to the past. However there is one form of memory that relates to future events. This is called prospective memory, and is the memory for things that we need to do in the future, for instance remembering to go to the doctor at 9a.m. on Tuesday, or remembering to check the cake after it’s been in the oven for an hour. People with dementia have difficulties with prospective memory, meaning that they find it hard to remember to do at the right time things that they want to do or have agreed to in the past. Prospective-memory difficulties lead to pots on the stove boiling dry and not being ready on time.

Tips for people with dementia

Use memory aids to help with your short-term memory: lists, notebooks, diaries and calendars. Electronic devices such as smart phones can help with prospective memory if you set alarms to remind yourself to do things at certain times. Write notes and leave them where you will see them at the right time (e.g. place a note at the front door for when you are leaving the house—have you got your keys, phone and wallet?). Have a routine for things so you don’t have to rely on your memory as much. Program important phone numbers into your phone.

Having difficulties with short-term memory means that it is easier to lose track of what day and time it is. Put clocks in every room. Have a calendar in a prominent place, make a note of the day, date and month in the morning, mark off the day each evening; make this part of your routine.

Carers need to be aware of and compensate for the poor short-term memory of people with dementia. Give instructions one sentence at a time, or a phrase at a time, or even a word at a time.

Try to guess at what stage in their past the person with dementia believes they are living. For some people with dementia there is a gradual shift into the past, for others the shift is more pronounced. Do they think they are aged in their eighties with three grandchildren? Or do they believe that they are aged in their fifties and working? Or do they think that they are in their twenties with young children? Talking with the person with dementia in a way that is consistent with their beliefs will be less confusing for them. Giving him or her activities that fit within their beliefs will also be more meaningful for them. For instance, a gentleman who believes he still works may find it meaningful to get ‘dressed’ for the office, and sit at a table and sort cards on a topic relating to his past employment. A woman who thinks she has young children may enjoy folding children’s clothes or cloth nappies, or looking after a baby doll.

The poor short-term memory of people with dementia means that they forget the pleasure and fun they shared with you. If it is important to you that they remember some of the things you do together, take photos of you doing things together and things that you have seen and display these in a place where the person will see them (the mantelpiece, fridge or bedside table). This will help them relive the experience (if not the memory).

When talking with people with dementia, instead of asking questions about recent events, comment on things that you can both see, smell, hear or taste at that time. Discuss the people, animals and things in nature that you experience around you. There is no point in arguing with a person with dementia on a point relating to their memory; if he doesn’t remember that you visited yesterday or that you told him that information 5 minutes ago, insisting that you did won’t convince him.

Difficulties with memory mean that people with dementia are constantly re-creating their past using the faded memories they have and clues from the present. Imagine waking up and not remembering where you are or how you got there. You’d try to figure out what happened based on your last memory (e.g. I was buying bananas in the fruit shop) and clues from the present (I’m lying down and there is a woman who is in some sort of uniform, maybe she is a nurse?). For people with dementia, it may be difficult to piece together an accurate understanding of their current situation because their ‘recent’ memory may be from quite far in the past. People with dementia sometimes make up an imaginary explanation to compensate for their loss of memory. We call this confabulation. Giving the person with dementia information in their environment about the present may help them understand their current situation. Some nursing homes encourage residents to furnish their room with familiar objects and furniture—these clues can help the person with dementia think of the care facility as the place where they live.

Difficulties with attention

Babies find the world endlessly fascinating to the point of being overstimulating. Everything is new and interesting and they are easily distracted by the next new, noisy, bright or moving thing. Being able to focus our attention on one thing at a time is an ability that we develop. Being able to concentrate in this way is useful in getting things done. We see people working intently on their laptops at cafés, tuning out with their mind the hustle and bustle around them. Tuning or blocking out distractions is part of focusing attention. We can tune or block out distractions physically such as when we close our eyes or cover our ears when we’re trying to think.

People with dementia lose their ability to focus their attention. They find it especially difficult to cope in noisy situations with many people. When sharing activities with people with dementia, it helps them if we can take away potential distractions so that they don’t have to spend mental energy screening out that information. This could mean switching off the radio or television, taking them into a quiet room without other people, and removing things unrelated to the activity. When talking to the person with dementia, give them one piece of information at a time, and give them time to take it in before presenting the next piece. For people with severe dementia, it can be confusing to have two people visiting or taking care of them. It may be easier for them to focus their attention on one person at a time. If a second person is helping with personal care, they can be an extra set of hands as unobtrusively as possible.

People with dementia cannot concentrate for as long as other adults, since for them focusing attention takes much more mental energy. We need to watch for signs that the person is no longer interested in an activity or that they are tiring. Such signs could be that they stop looking at the activity or person and start looking away, they stop participating, or they say they want to stop. In mild dementia, they may be able to participate intensely for 45 minutes to an hour. In more moderate dementia, about half an hour, and in severe dementia 5 to 15 minutes might be all they can manage.

Tips for people with dementia

Noisy group situations can be difficult to cope with because you need to spend so much energy to concentrate on one thing. If this occurs, take time out by going to sit in a quiet room or in a quiet place outside. If you’re in a situation where it is difficult to leave the group (e.g. at a family weekend together), put on a pair of headphones with some relaxing music and close your eyes, or even use noise-cancelling headphones.

Difficulties with initiation

To initiate means to take the first step to start something. We need to think about wanting to do something and then start the process of doing it. Initiation is critical to even simple activities such as getting dressed, having something to eat or having a conversation. The only common activity that doesn’t necessarily require initiation is sleeping; sometimes we just drift off to sleep without meaning to. Initiation is also needed for more complicated activities such as going out to the shops, paying a bill or making a meal.

Apathy is almost universal in people with dementia. They lose their ability to initiate, which means that they lose their get up and go, their ‘on–off’ switch gets stuck on ‘off’. They may not think of getting dressed and instead stay in their pyjamas all day. They mean to pay a bill but do not get around to doing it. We need to flick ‘on’ the activity switch for them. Some people with dementia might just need help to initiate the start of an activity, while others might need help initiating each step of that activity. We can do this by asking them to start doing things. Alternatively, we can leave out objects that may prompt them to start something. Laying out their clothes on their bed may encourage a person with dementia to get dressed. Putting the bill on the dining-room table with a note saying ‘I am now due, please pay me’ may prompt the person with dementia to pay the bill.

Difficulties with decision making, problem solving and planning

Decision making, problem solving and planning are more complex types of thinking that develop later in childhood. Decision making involves choosing between two or more alternatives by considering the possible consequences of those choices. Problem solving involves developing possible solutions for a problem and then deciding between those possible solutions. Planning involves working out the steps towards a goal then using problem-solving and decision-making strategies for each step. Even as adults, decision making, planning and problem solving can be difficult and require a lot of mental effort and energy.

The principle of ‘last in first out’ of the brain of a person with dementia that I described in relation to memory also applies to decision making, problem solving and planning. Relatively early in the disease, people with dementia lose the ability to first plan and problem solve, and then the ability to make complex decisions.

Decision making, problem solving and planning all involve working with thoughts or abstract ideas rather than real-life objects. When we make decisions, we draw on our memories of past experiences to imagine the future consequences of each alternative, and choose the most appealing consequence. When we problem solve, we create in our minds a range of possible solutions. People with dementia have more difficulty with abstract thought, with using logic to imagine consequences and create solutions within the parameters of the problem.

We usually need to do most of the planning and problem solving for people with dementia. However, as much as possible we should involve them in decision making. Freedom of choice is something that is important for us as humans to have. For people with moderate to severe dementia, you may need to present the alternatives visually to make the decision easier—for instance, showing them the packages of chicken and sausage from the fridge when asking what they’d like to eat, or showing them a photograph of a beach or a park when asking where they would like to go.

Tips for people with dementia

There are often many pieces of information to consider in decision making, problem solving and planning. For simpler decisions we usually keep all the information about the possible choices and consequences in our short-term memory. Consider writing down this information so that you don’t have to keep it all in your head. For more complex decisions you could write down the competing choices to make the decision-making process easier (such as the details of the different holiday locations you are considering). You could also write down the consequences (a list of pros and cons) or you could write down possible solutions to problems. You should definitely write down steps of a plan, because seeing it on paper will help you work out where things don’t make sense or problems that could arise.

If you find that you’re taking longer than you would like to make decisions that are necessary but not very important, such as what clothes to wear, or what to put in your sandwich, then simplify those decisions. For instance, match your clothes into sets and hang these together so you can just take a set out of the cupboard each morning. Put all the sandwich ingredients for a standard sandwich in the one spot in the fridge, even the things that don’t need to be refrigerated, then just get them out and make the sandwich.

Difficulties with speech and comprehension

Conversations are important ways of interacting with other people. In order to understand what someone else is saying we have to process the sounds the other person makes and interpret the meaning of the words within the sentence. To reply, we decide what idea we want to express, find the right words and the right order for the words, and then say them aloud.

Any (and many) of these steps can go wrong for a person with dementia. Usually, they start with having trouble expressing themselves, with finding the right words and putting them into a sentence. Their poor memory means that they find it hard to follow complex stories and even long sentences. They may lose their understanding of the meanings of words, though usually keep their ability to read tone and body language.

Difficulties with perception

As children we are taught that we see with our eyes, hear with our ears, smell with our nose, taste with our tongue and feel through our skin. This isn’t entirely accurate. Our sensory organs are the receptors; information they collect is sent to the brain, which processes and interprets the information. We actually see, hear, smell, taste and feel with our brains as much as our sensory organs. For example, our brain interprets the pattern of light hitting our retina as a seagull, the pattern of vibrations hitting our eardrums as the sound of waves crashing, and the chemicals entering our nose as the smell of the seaside.

The ability of people with dementia to interpret visual information changes as their brain deteriorates, even if their eyesight is fine. They sometimes do not ‘see’ objects that are right in front of them. This may be because they do not recognize the object for what it is because it does not match their schema or mental template of what that object should look like. An extreme example is someone whose schema of a telephone is from the 1970s—they would therefore not recognize a mobile phone as being a telephone. Alternatively they may have an incorrect memory of what the object should look like: for instance it is difficult to find a book when you think the cover is red but it is actually white.

People with dementia also lose their ability to detect and distinguish smells, and this happens early in the course of dementia. Since smell contributes a great deal to how we perceive flavour, they also have impaired ability to taste. This may result in changes to their appetite or the food they like.

If the person with dementia seems to have difficulty with seeing things, and this is not due to a problem with their eyesight, then modify their environment to help them see important objects. Reduce visual clutter so the person doesn’t have to use their attention to block out irrelevant objects. Aim for maximum contrast between the things you want them to notice and their background. Text should be large (32-point minimum) and be black on white, or white on black. Food should be contrasting in colour to the plate—a white sandwich or white fish and mashed potato on a white plate on a white tablecloth is less obvious than when placed on a blue plate. Similarly, you could place a white doily between a dark wallet and dark wood table to make the wallet more obvious. If the person is having trouble finding the toilet, then getting a contrasting toilet seat may help.

Changes in personality, and difficulties controlling feelings

Personality, character, temperament—these all describe our individual and unique ways of behaving, feeling and thinking. We think that our personality develops through a combination of our genetic disposition (for example, a disposition to be extroverted or introverted) and our upbringing and experiences through life. A naturally extroverted person could end up being bossy and overbearing, or motivating and outgoing. A naturally introverted person could end up being shy and retiring, or quietly confident.

There is no clear pattern in how personality changes as a result of dementia, however a change in personality is often one of the early symptoms of the condition. Some people with dementia seem to have their personality characteristics exaggerated. Someone who had a short fuse gets angry even more quickly, someone who was a worrier is even more anxious. However, some people with dementia seem to have their personality traits softened. Someone who used to be grumpy becomes more easygoing, someone who was outgoing is more passive.

Exaggerated personality may develop because the person’s ability to judge the appropriateness of an action has deteriorated. Most of us have the ability to moderate or censor our actions, so we stop and decide whether a particular action is a good idea before doing it. When we are feeling angry this ability to self-censor stops us from punching the person we are angry with or throwing the teapot out the window because we may be arrested for assault or might smash the teapot. Some people with dementia will act more impulsively and behave according to their personality with less consideration of the consequences. The same part of the brain that decides whether a particular action is a good idea, the frontal lobe, also helps us control our feelings. This is an ability we (well, most of us anyway) develop in early adulthood. Toddlers and teenagers sometimes seem to have very labile, rapidly fluctuating and unreasonable emotional reactions because this area of the brain isn’t fully developed. Some people with dementia act this way too, because of deteriorations in the frontal lobe.

Dampened personalities in people with dementia may occur because the areas of the brain where personality is ‘stored’ have been damaged, or because they lack the initiative to behave or react the way they previously did.

Difficulties with movement

Dementia affects speed, coordination, balance and strength because these abilities are controlled by the brain. This means that people with dementia are not as agile as they were previously, are more likely to fall and can have poorer fine motor skills. When planning activities, their current physical abilities should be taken into account. Physical activities that they could previously manage may be more difficult now: they might not be able to walk as far, might not be as comfortable on uneven ground and could tire more easily.

Equating people with dementia and children

I have discussed how the deterioration of mental abilities with dementia mirrors the development of these same abilities in children. It can be useful to think of people with mild dementia who can travel independently as being similar to children aged eight to twelve years, people with moderate dementia who are independent in their self-care as being similar to children aged five to seven years, people with moderately severe dementia who may need prompting but can dress and shower themselves as being similar to children aged three to five years, and those with severe dementia who need physical help with self-care as being similar to children aged younger than two. The similarities can help you think about what the person can do independently, including the decisions about their life and safety that they can make independently, and the kind of activities they might do and enjoy.

However, this does not mean we should treat people with dementia the way that we treat children. There are some important differences between people with dementia and children that we should be aware of:

It may be helpful to think about these similarities between persons with dementia and young children:

Theory of unmet needs and behavioural and psychological symptoms of dementia

There is a theory that suggests many of the symptoms of dementia (such as agitation, aggression, pacing, yelling, arguing and depression) arise because people with dementia have needs that are not being met. They may feel disturbed or uncomfortable but do not recognize the reason for these feelings, or they may not be able to express what is wrong. Young children often act in difficult ways because of similar reasons. Research has shown that identifying and attending to these needs of people with dementia decreases these behaviours that for carers can often be distressing and difficult to cope with. Research has also shown that doing activities can decrease these behaviours. These activities seem to be more successful in decreasing behaviours when they are tailored to the person with dementia.

The unmet needs of people with dementia generally fall into three areas.

  1. Physical health—they might be in pain, feel too hot or too cold, feel unwell, hungry, thirsty or need to use the toilet.
  2. Stimulation—they may feel overstimulated and not be able to cope with a situation that is too noisy or where there are too many people; or they may be understimulated and feel bored or unoccupied, and have excess energy.
  3. Company—they may want someone to be with for company, reassurance and companionship.

What the science tells us

Dementia is the umbrella term for a group of neurodegenerative conditions in which brain deterioration causes the symptoms of dementia. Different types of dementia affect the brain differently, which is why they produce different symptoms. Most types of dementia are defined by the causes of the brain deterioration, but some are defined by the location of the deterioration. Four common types of dementia are described below; there are many others.

The changes in the brain associated with Alzheimer’s disease, neuritic plaques and neurofibrillary tangles tend to damage neuronal material in the hippocampus first. The hippocampus helps with the formation of new memories. That is why short-term memory loss is one of the early symptoms in people with Alzheimer’s disease. The hippocampus also deteriorates as part of normal brain ageing, so our short-term memory ability also deteriorates as we grow older, which makes it difficult to distinguish the early symptoms of Alzheimer’s disease from normal ageing.

Another change in the brain of people with Alzheimer’s disease is general atrophy or shrinking of the brain, caused by death of the brain cells, and loss of the connection between the cells. The brain of someone with Alzheimer’s disease shrinks up to three times faster than the brain of an older person without the condition. This means that the whole brain of the person with Alzheimer’s disease starts working less effectively, it works more slowly and inconsistently and sometimes does not succeed in its tasks. The cognitive decline in Alzheimer’s can be thought of as a gentle slope, starting off mildly and with loss of ability decreasing slowly and increasingly across time.

Vascular dementia is caused by large, small or very small strokes in the brain. The strokes or transient ischemic attacks might be so mild that the person might not realize they have had a stroke. The strokes result in the death of cells in one large area or multiple small areas of the brain. The symptoms will depend on which brain areas have been affected. This is similar to people who have a stroke that affects them physically on only one side of their body. People with vascular dementia can have a range of different symptoms and can perform poorly on one aspect of thinking yet still perform well in other aspects. The cognitive decline in vascular dementia is more like downward steps, with each step corresponding to a new stroke or mini stroke in the brain.

In fronto-temporal dementia the frontal and temporal lobes deteriorate much more than the rest of the brain. This can be caused by a variety of issues. The frontal lobe is the part of the brain responsible for problem solving, planning and modifying behaviour. So people with fronto-temporal dementia tend to have poor impulse control, poor planning and poor problem-solving skills. The temporal lobe includes the hippocampus and other brain areas involved in memory formation, consolidation and retrieval, so memory is affected depending on how much the temporal lobe is affected.

Dementia with Lewy bodies (or Lewy body dementia) is named after the Lewy bodies that develop in brain cells. Lewy bodies are clumps of alpha-synuclein and ubiquitin proteins, and are thought to cause the death of brain cells. People with Lewy body dementia tend to have variable mental abilities, so sometimes they seem almost normal and at other times they are confused and disoriented. They often have visual hallucinations or delusions, meaning that they see things that are not really there or believe things to be true that are not. They also often have a tremor or stiffness in their movements.

With the exception of vascular dementia, the causes of the other common forms of dementia are not known. We know, however, about a range of factors that can decrease the risk of developing any form of dementia, such as looking after our hearts and staying within the recommended guidelines for cholesterol, blood pressure and weight; eating a healthy diet; engaging in regular physical exercise and regular mental exercise; not smoking or drinking to excess; and avoiding brain injury.

We used to believe that we were born with a set number of brain cells, called neurons. It was thought that throughout life we gradually lost these neurons. Then scientists discovered that the brain grows new neurons, and that the environment affects the rate of growth and survival of these new neurons. In mouse models of Alzheimer’s disease, new neurons continue to grow, and growth rates can be stimulated through physical, mental and social activity.

Identifying the cognitive abilities of the person with dementia

We need to understand the cognitive abilities of the people with dementia we care for so that we can modify the activities to ensure they can do them successfully. Table 1 is intended to help you identify the current thinking abilities of the person with dementia you care for. The table focuses on abilities that will affect what activities you do with them, and how you present them. It is not intended to replace a formal cognitive or neuropsychological assessment to diagnose dementia, or to assess change in cognitive abilities. Rather it is intended to help carers figure out what the person with dementia may be able to do, and also may help show relative strengths and weaknesses of the person with dementia.

Those of us who get to know people with dementia after they have developed dementia find it easier to accept and work with the strengths and personality of the person as we find them, since we did not know them beforehand. Carers who have known the person from before the onset of dementia sometimes spend emotional energy noticing and worrying about the mental abilities that have deteriorated and remembering the person in their prime. While these memories are important, it can be more productive to focus on the person’s current strengths and on how to maximize their current abilities.

It is sometimes very difficult to judge what a person with dementia can do. As a psychologist, I’m often surprised at their abilities when I test a person—which can be much worse or much better than I expect, or can be unexpectedly good in one aspect of thinking or memory. I tend to expect that people with dementia with good social skills will also have good mental abilities, but social skills and mental abilities do not always correspond. Alzheimer’s dementia is the most common form of the disease and so most professionals have a ‘prototype’ of dementia that is most similar to Alzheimer’s disease, with memory problems being the predominant early complaint. Other types of dementia often are quite different. For instance, someone with vascular dementia may have relatively good short-term memory but very poor judgment. Family and professional carers often underestimate or overestimate the abilities of a person with dementia.

The only way to know what a person with dementia can do is to be observant, and to consider each ability individually. You may need to make these observations before completing the tables. You may be surprised at what the person you care for can still do, and realize that you’ve been doing too much for him or her. Or you may be surprised at how little they can do, and reflect that they have been understanding less of what is going on than you thought or may need more supervision than you have been giving.

It may be useful to review the table and update your answers if the person with dementia’s condition changes.



Additionally, take note of and record the following information (particularly if this information is being completed by professional care staff, or will be shared with professional care staff):