Understanding Challenging

Behavior in Huntington's Disease
By Julie Snowden

The need for recognition of problem behaviors

Changes in behavior are a central feature of Huntington's disease (HD), which arise because of physical changes in the affected person's brain. Behavioral changes are often the most distressing part of the condition and create the greatest challenge for caregivers. Nevertheless, they have been relatively neglected by medical professionals and researchers and are often poorly understood.
One reason is that they are less obvious than involuntary movements and may not be apparent during the brief period of a clinic visit. Moreover, problem behaviors are most likely to occur in the home and to be directed towards those family members and caregivers to whom the person with HD is closest, not towards relative strangers. Thus, behavioral problems are likely to be underestimated by outsiders.
Health professionals are however, at last beginning to realize the enormous impact on families of behavioral symptoms. If new treatments for HD are to be successful they will need to benefit the behavioral aspects of the condition as well as the movement disorder, which means that it is increasingly important that we should understand why those behavioral changes occur. So how can we unravel the different components of behavior?
HD is often said to give rise to a triad of symptoms: a disorder of movement, together with changes in intellect and in mood. Both the intellectual and the mood changes are likely to contribute to how a person behaves. How people behave reflects the way that they think (cognition) and how they feel (emotions). To understand HD behavior it is necessary to understand how the structural changes in the brain alter both thinking and emotions.
Cognitive changes in HD are specific and predictable
The cognitive changes in HD are very often described as a dementia. Usage of the term dementia is unfortunate since it is very often taken to mean a generalized impairment, the implication being that mental abilities are impaired in a global and diffuse way.
People with HD do not have global intellectual impairment. There are good reasons why that is so. Degenerative diseases that affect the brain, such as HD, do not damage the entire brain in a non-specific way. Rather they preferentially damage and disrupt the function of certain parts of the brain, while other parts of the brain continue to function well.
Since different parts of the brain serve different functions, the type of mental change that a person has will be characteristic for a particular disease and will be governed by the regions of the brain preferentially involved. Thus, mental changes are both specific and predictable.
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Brain changes in HD
HD particularly affects deep structures within the brain, known as the striatum, which are important for the control of movement. These deep structures have connections to the cerebral cortex (the outer covering of the brain) and in particular to the front parts of brain (frontal lobes). Many of the cognitive changes in HD are a direct result of impaired functioning of these specific brain circuits, which link the striatum to the frontal lobes.
Functions of different brain regions
So what do the different parts of the brain do? The more posterior parts of the brain are important for making sense of what is perceived through the senses. They are important for processing visual information and being able to recognize what one sees: for example, recognizing that a chair is a chair, and knowing whether two chairs look the same or different. The posterior parts of the brain are important too for processing auditory information: in converting sounds of words into meaning. Thus, they are necessary for recognizing that the sound d-o-g refers to the four-footed animal that barks and not, for example, to the bird that flies in the sky or the fish swimming in the sea.
The ability to process and interpret what is perceived through the senses can be thought of as the tools or building blocks of thought. These building blocks, which provide the foundation of cognition, are preserved in HD. They may however, be impaired in other brain disorders. A person who has Alzheimer's disease or who had had a stroke may have difficulty recognizing objects and other visual stimuli. They may also have difficulty understanding what words mean. The reason is that those conditions can affect the parts of the brain important for these fundamental information processing skills.
If the posterior parts of the brain are important for the tools of thought, for recognizing what we see and hear, what is the role of the anterior (front) parts of the brain, which are damaged in HD? The front parts are the "captain of the ship".
Imagine that on a ship there are a variety of instruments, used for navigation and for communication. They are like our instruments or tools of thought. However, even when those instruments are all in working order, the ship does not function on its own. It needs a captain to plan and organize the journey, to attend to the instrument panels and communication systems, abstract out relevant information and ignore what is not relevant, to check incoming information and to have the flexibility to alter a course of action if circumstances change. The captain has a supervisory function, in regulating and controlling what happens.
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The front parts of the brain are important for those same functions and they are sometimes referred to as the executive or supervisory system of the brain. These regions are necessary for planning, forward-thinking, goal-directed behavior, for the ability to organize behavior, attend to what's relevant and ignore what is not relevant, to monitor and check performance, and to adapt behavior to altered circumstances and different social situations. It is in these areas of cognition that people with HD have particular difficulties.
Clinical assessment of cognitive skills
People who attend an HD clinic may sometimes be asked to undergo psychological tests. The tests typically tap a range of cognitive abilities and are designed to identify the sorts of difficulties in thinking that the person has. This information is helpful both in understanding the person better and in monitoring change.
As new treatments for HD become available it will increasingly become essential information for evaluating the benefits of those treatments. It is by means of these cognitive tests that it has been possible to identify the characteristic pattern of difficulties in people with HD: the problems in planning, structuring and organizational skills, in attention and attention switching, and in mental flexibility.
The Impact of cognitive change on Behavior
Initiative and Drive
The ability to plan and think ahead is an important motivator of behavior. We think of tasks that need to be done and why we should do them now. That is, we are stimulated into action.
Since the capacity for forward thinking is impaired in HD, it means that people with HD become essentially passive. They react to things that happen, but do not actively initiate activities. They are reactive but not proactive.
One common characteristic is that people with HD may seem content to do nothing. If left to their own devices, they might lie in bed all day or sit watching television. This can of course, be exasperating to a busy partner, who may resent the fact that all duties and responsibilities fall on them. However, the person with HD is not being lazy. The brain changes in HD mean that there is a loss of drive and initiative, so that the person cannot self-motivate. The stimulus needs to come from outside rather than within. Doing tasks together can be helpful since the activities of the partner acts as a stimulus to the person with HD.
Thinking ahead
The ability to think forward means that we sacrifice short-term rewards for longer-term goals. An obvious example is that young people study for exams even though they would prefer to be socializing with friends, because they think that it will be beneficial to their future prospects. We don't, as a rule, spend all our monthly salary on an expensive luxury, because we know that we will need money to buy food over the next month. That is, we are able to see the future consequences of a course of action and we modify our behavior accordingly.
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If the capacity for thinking forward is lost, as in HD, then the person does not see future consequences, and behavior is governed much more by immediate needs and desires rather than longer-term goals. The person with HD may seem to want "immediate gratification". The person is not being deliberately demanding. It is just that they are no longer able to think long-term.
It is important to recognize this characteristic because it has implications for our interactions with people with HD. Imagine, for example, that a friend invites you to go shopping that afternoon, and that you answer "no". There may be multiple reasons influencing your decision: you do not want to be in crowded stores on a fine day, you are saving for your holiday and do not want to be tempted to spend money, you ought to attend to tasks at home. There would be no point in your friend inviting you again after ten minutes, because all those reasons would still apply.
For someone with HD, the response "no" may be much more short-term. It may mean that the person does not feel like moving from their chair at that moment, or wants to continue watching the current television program. In ten minutes, the situation could change. It is not that the person with HD is being awkward or fickle. It is that decisions are based much more on immediate than long-term considerations.
Organizational skills
Our activities involve organization and ordering. In the office, we might, for example, file away papers relating to one task, before getting out of the filing cabinet papers relating to another task, so that the two sets of material do not become muddled. We prioritize things that we need to do so that we can meet deadlines.
People with HD have difficulty with organization and sequencing, so that their performance can often seem disorganized. This can represent a problem in the early stages of HD when people are still at work. The person with HD will not have forgotten how to do their job, but performance may be lowered because of difficulty in organizing the work efficiently.
Organizational Skills:
Our activities involve organization and ordering. In the office, we might, for example, file away papers relating to one task, before getting out of the filing cabinet papers relating to another task, so that the two sets of material do not become muddled. We prioritize things that we need to do so that we can meet deadlines.
People with HD have difficulty with organization and sequencing, so that their performance can often seem disorganized. This can represent a problem in the early stages of HD when people are still at work. The person with HD will not have forgotten how to do their job, but performance may be lowered because of difficulty in organizing the work efficiently.
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Attention
People with HD have difficulty doing two things at once. Many of the things that we do each day that we take for granted involve coping with multiple tasks simultaneously. For example, when driving a car, we carry out the mechanics of driving, whilst also attending to road signs and conversing with a fellow passenger. We carry out these tasks as relatively automatic routines.
To understand the difficulty encountered by people with HD, think back to the experience of being a learner driver. You may remember a time when you needed to concentrate so much on the mechanics of driving, such as steering, changing gear and signaling that you did not notice road signs and traffic. You may have found it difficult to hold a conversation while driving. That is, your attentional resources were overloaded. The situation is similar in HD. Activities that we take to be relatively automatic, such as walking and talking require more conscious attention for people with HD, so their attention system is easily overloaded.
Aside from overload, there is another reason why people have more difficulty carrying out two tasks; difficulty in switching of attention. Under normal circumstances, one of the reasons that we are able to deal with multiple tasks, even those that require conscious attention, is that we can switch attention between tasks. We can, for example, switch attention momentarily away from a television program in order to answer a question and revert back to the program without difficulty.
A person with HD has difficulty doing so. The practical implication is that people should try to avoid where possible placing multiple simultaneous demands on someone with HD. One thing at a time is best. It is worth keeping in mind that tasks that seem easy to us, such as answering a question while watching television may actually be difficult for someone with HD.
Self-monitoring and awareness
People with HD have difficulty in monitoring and checking aspects of performance, so they may not be aware of errors that are apparent to others. The impression given to an employer when someone is in the early stages of HD may be that the person has become careless. That is not the case. It is simply that the person is no longer able to carry out efficiently the monitoring program that would keep errors in check.
It is worth bearing this difficulty in self-monitoring in mind when individuals with HD declare that there is nothing wrong with them. They may genuinely be unaware of the changes that are so evident to others.
Mental flexibility
Loss of mental flexibility means that people with HD may seem rather rigid in their behavior. They may like their own routine, and seem unwilling to try anything new. They may seem poorly adaptable to changed circumstances and new situations.
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From a management point of view the implication is that changes, wherever possible should be introduced gradually. It is better that the person with HD is told of prospective changes in advance and has time to get used to them rather than have them imposed abruptly.
HD patients have difficulty seeing things from alternative perspectives. This inevitably has an impact on inter-personal relationships. The person with HD may sometimes seem thoughtless and selfish. However, they are not being intentionally uncaring.
To have sympathy or empathy with other people one needs to be able to see things from the other persons point of view, to appreciate the other person's own needs and feelings. In HD the brain, changes may prevent them from seeing things from another perspective and appreciating the needs and feelings of others.
Mood changes in HD
There are a number of emotional changes that may occur in HD. People with HD may show irritability and feelings of anxiety and agitation. They may be emotionally volatile, seeming to flare up and losing their temper for no apparent reason. Depressive symptoms may also occur.
In the later stages of HD, people may show emotional blunting with a loss of the emotional warmth and range of emotional expression that they demonstrated before they became ill. One can think of these mood changes as separate from the cognition-based behavioral changes described above.
Nevertheless, it may well be that there are interactions between the two. Suppose for example that a person with HD loses his/her temper when asked a question while watching television. The person is showing the volatility and loss of emotional control, which are mood-based changes of HD.
However, the person is being asked to do something that is actually rather difficult for someone with HD - switching attention from one task to another. The feeling of irritability might stem from the fact that the person finds it hard to switch attention efficiently away from the television to the conversation at hand and then back to the television.
It is easy to interpret emotional outbursts in people with HD as "out of the blue" or "over nothing". It is worth bearing in mind that what may seem trivial to us may actually be a difficult task for some one with HD. It may be that cognitive demands are being placed on the person with which he/she is unable to cope and that this is the basis for the outburst.
Regardless of the cause it is better to avoid confrontation in response to an outburst. It can be difficult for people with HD to see another person's point of view and to follow their reasoned argument even during periods of calm. They will certainly have difficulty doing so during periods of high emotion.
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The frequency of behavioral problems in HD
Behavioral changes vary in severity in different people. For some people they may pose few practical problems whereas for others they create major problems in management. Also, some behavioral problems are more common than others.
We have developed in Manchester a questionnaire of Problem Behaviors for use with HD patients and their carers. The questionnaire taps a range of aspects of behavior including drive and initiative, quality of task performance, the ability to persevere on tasks, judgment, self care, thoughtfulness towards others, mental flexibility, social awareness, emotional warmth, temper control.