Feature

Behaviour and Brain Damage

Brain dysfunctions in various forms have interesting and important effects on behaviour.

Dr Nigel V. Marsh

Our knowledge of fundamental issues concerning the structure and function of the human brain is still quite limited. This is perhaps best illustrated by an article in Science, in which Professor John Lorber, a British neurologist, poses the question "Is your brain really necessary?" Scientific investigation of the relationship between brain function and human behaviour is the primary focus of a newly emerging discipline known as neuro-psychology.

Interest in this area is not restricted to neuropsychologists, and the writings of Oliver Sacks have provided the public with non-academic accounts of what can happen to people when they suffer from some form of brain impairment. Indeed, the film version of Sacks's Awakenings indicates that it is not only the neuropsychologists but also the general public who are fascinated by what occurs in the space between people's ears.

Despite theoretical progress in neuropsychology, the application of these findings to the management of people suffering from neurological disorders has yet to be fully realised.

In New Zealand, such training in applied human neuropsychology usually occurs within more general clinical psychology training programmes. The use of specialised psychometric tests to detect and localise brain lesions has proven a useful adjunct to other common diagnostic procedures such as EEGs and CAT scans. However, it is the relationship between how people perform on the psychometric test and how they will perform in their everyday life that is of most use in rehabilitation planning.

Such knowledge also allows the neuropsychologist to provide the person's relatives or caregivers with sound, practical advice concerning the management of the person once they are discharged home from hospital.

At Waikato University's Department of Psychology, we have recently been examining the relationship between performance on psychometric tests and everyday behaviour, using different groups of neurologically impaired people recruited through Waikato Hospital.

Clinical psychology student Denyse Kersel is examining the effects of visual neglect in a group of elderly stroke patients. Visual neglect can be a consequence of stroke, and results in the person failing to process the information from part of their visual field.

Depending on the type of test used, Kersel found that up to 48% of her patients showed signs of visual neglect. The patients' independence in activities of daily living was also assessed. One of the tests of visual neglect was shown to be a useful predictor of the patients' level of independence. Therefore, use of this test allows the neuropsychologist to not only detect the presence of visual neglect, but also gain information on a patient's ability to live independently.

Jennifer Cummins is studying the effects of head injury in children, and has found that they generally have no ongoing difficulties with attention, intelligence or visuo-spatial abilities, but some problems with language and memory.

As expected, Cummins found that some of the head-injured children were having difficulties at school. However, while there was a relationship between the children's memory abilities and their school problems, there was no relationship between their language skills and school progress. This suggests that rehabilitation procedures concentrating on memory skills are most relevant when integrating a head injured child back into a school environment.

Hydrocephalus is the condition which results when the volume of fluid around the brain increases. It is very common in people with spina bifida. James Webb has been looking at the neuropsychological abilities of a group of children with hydrocephalus.

Hydrocephalic children have difficulties in intellectual, visuo-spatial, attention and memory abilities, but no language problems. The children's attention and memory abilities were not related to their self-esteem or functioning in everyday activities. Their intellectual and visuo-spatial abilities were predictive of their ability to function effectively in their environment and their level of self-esteem.

While these studies do not present a complete picture of the relationship between neuropsychological impairment and everyday functioning, they do start to provide part of the answer.

Specifically, they indicate that for some neurologically impaired people, performance on psychometric tests does allow the neuropsychologist to make predictions about the patient's abilities in certain aspects of everyday functioning. The extent to which general principles arise across all patient groups can be established has yet to be determined.

Dr Nigel V. Marsh is an advanced lecturer in psychology at the University of Waikato.