The Interaction of Age and Diagnosis in Neuropsychological Test Results

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Abstract
The effects of age on neuropsychological test performance is an important issue in clinical diagnostic work. Although there is general agreement on the effects of age on control patients, there is considerable controversy over age effects in a neurological population. Two major reasons may be responsible for discrepant results across studies: biased subject populations and inadequate statistical procedures. The present study corrected for these problems, examining the test performance of 171 subjects classified by age (above 35, 35 and below) and diagnosis (right, left, diffuse, control). A weighted means analysis of variance found 7 significant age effects on 15 measures taken from the Halstead-Reitan. All measures showed significant Fs due to differences in diagnostic groups. No significant interaction effects were found. The results clearly support the contention that age effects are identical in the control and brain-injured groups. This indicates that age corrections based on the performance of a normal group are likely to be useful in increasing neurodiagnostic accuracy rates