Neuropsychology

Clinical neuropsychology is an applied discipline that uses the basic knowledge from experimental neuropsychologic research to develop reliable and valid procedures for assessing, managing, and rehabilitating persons who suffer from the behavioral, cognitive, and emotional consequences of neurological injury or disease. A variety of different tests of cognitive functions, such as memory, visual and auditory perception, language, and abstract reasoning, have been developed and shown to be sensitive to the consequences of localized brain damage or dys-function. Although not yet as extensively developed, similar tests of emotional functions (e.g., recognition of facial or vocal emotional expression) are available.

In assessing a person with known or suspected neurological injury or disease, the clinical neuropsychologist uses several such tests to draw inferences about the functional integrity of different brain areas and systems. The pattern of strengths and deficits shown by a particular individual on these tests (as judged against performance expectations based on the study of healthy persons of similar age and educational background) can be compared to the documented patterns shown by persons with known neurological injury or disease. The clinical neuropsychologist can thus determine whether the pattern of test scores is consistent with a particular neurological diagnosis.

Neuropsychological testing plays a particularly important role in diagnosis when a given illness (e.g., Alzheimer's disease) manifests primarily by changes in cognition and emotion (rather than in clear physical abnormalities). In addition to diagnosis, neuropsychological assessment plays an important role in giving information to health care providers, patients, and family members concerning specific strengths and deficits in cognitive and emotional functions and their practical implications. Neuropsychological testing is also used in the assessment of treatment effects (e.g., experimental drugs being tested to improve memory in persons with Alzheimer's disease) or disease progression, and in guiding the rehabilitation or clinical management of cognitive, emotional, and behavioral problems.

In selecting, administering, and interpreting neuropsychological tests, several factors need to be considered. First, specific tests should be selected on the basis of whether they meet accepted psychometric criteria. These criteria include demonstrated reliability (consistency of test scores obtained by the same persons when retested with the identical test or an equivalent form) and validity (sensitivity and specificity for the consequences of brain damage or disease). There should also be available normative data (average scores of healthy persons) comparable to the age, educational background, and other characteristics of the person being examined. In addition to test reliability, sensitivity, specificity, and available normative data, the impact of various patient characteristics must be considered. One characteristic known to affect test performance is the individual's age.