On the Importance of Collecting Local Neuropsychological Normative Data

The goals of neuropsychological assessment include not only an accurate description of neurocognitive strengths and weaknesses, but also the reduction of misclassification rates. Despite the availability of tests with acceptable psychometric properties, the value of neuropsychological assessment may be undermined by the lack of clear guidelines on what constitutes impairment, and the use of inadequate normative data. These challenges to accurate neuropsychological assessment may result in both Type 1 and Type 2 diagnostic errors. In this study, the prevalence of impairment was examined in 20 neurologically intact individuals following administration of a small battery of commonly used neuropsychological tests. Results revealed an unacceptably high number of false positive cases. This finding questions the applicability of imported normative data for South African individuals, a dilemma which can only be remedied through the development of substantial data-collection projects.