NEUROPSYCHOLOGICAL SYMPTOMS OF HUNTINGTON'S DISEASE
Randi Jones, Ph.D.
July 15, 1998
Huntington's disease (HD) is a neurological (brain) disorder; this means that a physical disturbance in the brain causes the death of neurons (brain cells) in the basal ganglia and an imbalance of neurotransmitters (the chemicals that regulate the cells). HD is an inherited disorder. Each child of parent with HD has a 50% chance of inheriting it. There are about 35, 000 individuals in the US with HD. Men and women are affected equally. If the gene is inherited, the disorder will occur, usually with an onset in the middle years. The symptoms involve movement, neuropsychological function, and emotions. Neuropsychological symptoms of HD are often difficult to identify but may be more debilitating than the early movement symptoms. Because there are changes in the brain of a person affected with HD, there are resulting changes in behavior. Some of these changes concern cognitive or mental abilities such as memory and concentration; other changes are emotional such as depression, temper outbursts, or suspiciousness.
The earliest neuropsychological signs may he apathy or lack of interest. It is difficult to identify the cause of apathy because it can look like laziness or irresponsibility. On the contrary, it is a sign that the connection between the basal ganglia and the frontal lobe of the brain which governs organizational ability has been damaged. Other early neuropsychological signs may be difficulty sustaining attention, problematic concentration, or inability to begin an activity. The inability to begin an activity or to complete an activity is seen in the occasional reluctance of the HD affected person to bathe or complete other personal care activities or to cook a meal. Try to think of all the small steps involved in taking a bath or cooking a meal. If one step is omitted, the rest cannot be completed. Consider what happens when some aspect of one of the steps is not what was planned, for example, there are no washcloths in the bathroom. This requires a change in the strategy for taking a bath, Our usual choices might include yelling for someone to bring one, dashing out in a state of disarray to obtain one, or looking in the tub to find a slightly used one. The HD affected person, however, may be stumped by this unexpected development and sit down on the tub or wander off to do something else. This inability to change strategies is referred to as a lack of cognitive flexibility and is a primary symptom of HD.
The memory disorder in HD is variable. With the disease progression, a "spotty" pattern may be seen in that certain aspects of memory may be more severely affected than others and it may be worse on some days than others. HD affected individuals are usually able to remember information if given enough time. The retrieval aspect (finding that tennis racket in the back of the closet) of memory is faulty, whereas the storage of information can be relatively intact. It is thought that attention is a factor in the inconsistency of memory problems. If the affected person is interested and engaged, the ability to remember will be better. Short-term memory (for recent events) may beworse that long-term memory (events in the more remote past); however, the HD affected person, especially early in the disease, may still be able learn new information if given many opportunities to practice and given prompts. As the disease progresses the over-all ability to remember declines. The inconsistent memory pattern in the early to middle stage is especially problematic for family members who may not be able to predict how much their affected family member will remember on a given day. The affected person may be insulted by the assumption that he/she cannot remember on a good day, but may be incapable of remembering on another day. This requires the family to he particularly aware of the affected person's state at a specific point in time. The necessity for repeated observation and assessment by the caregivers can be very exhausting, particularly when the HD affected person may not be aware of his/her limitations or may not he able to express that awareness.
Problems which look emotional or psychological but which are caused by brain dysfunction concern the person’s reduced ability to inhibit certain behaviors. These may includeuncharacteristic cursing, insulting remarks, crude social behavior, and occasional inability to control impulsivity or violence; similar behaviors maybe seen in a person who has had too much to drink. We all have such thoughts and impulses, but our intact brains filter these thoughts and prevent the more socially inappropriate ones from becoming actual behavior.
In summary the early neuropsychological symptoms of HD include mental inflexibility, inability to maintain attention, poor concentration, difficulty beginning an activity or completing an activity, and decline in organizational skills. Related symptoms include emotional problems such as depression or poor self control, and decreasein insight and judgment. If depression is present it can intensify the cognitive symptoms. Depression is very amenable to treatment with antidepressants. If you suspect that your affected family member is depressed, evaluation for depression would be very useful and treatment might lessen the severity of problems with apathy, memory and attention. It is very important for family members to remember the degree of variability in their affected loved one's symptoms and the importance of retaining one's own flexibility and sense of humor even when the affected family member is unable to do so.
Copyright © 1998 Randi Jones, Ph.D.