Repeated Cognitive Tests Needed for Accurate Diagnosis of Mental Function

(Ivanhoe Newswire) -- Taking a cognitive test only once may not be enough to accurately diagnose a person's mental functioning.

A University of Virginia researcher finds scores are more accurate when you give patients repeated tests over a short period to diagnose learning disability, progressive brain disease or impairment from head injury.

Cognitive psychologist Timothy Salthouse, Ph.D., gave 16 common cognitive and neuropsychological tests to participants in age groups 18-39, 50-59, and 60-97. Results from his studies show the variation between someone's scores on the same test given three times over two weeks was as large as the variation between the scores of people in different age groups -- a major inconsistency that questions the worth of single, one-time test scores.

"I don't think many people would have expected that the variability would be this large, and apparent in a wide variety of cognitive tests -- not simply tests of speed or alertness," study author Timothy Salthouse, Ph.D., University of Virginia, was quoted as saying.

Psychologists often give several types of tests such as vocabulary, word recall, and spatial relations to understand normal function and diagnose impairment. But Salthouse says the one-time assessments can make it difficult to tell whether someone is truly impaired, truly improving or worsening, or just having normal short-term fluctuation.

Salthouse proposes a procedure that bases understanding on several parallel assessments within a relatively short period. He believes the results would probably be more stable and offer a better basis for monitoring individual change.

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SOURCE: Neuropsychology, 2007;21:401-411