Neuropsychological profiles of cortical and subcortical dementia: underlying constructs and group differences

Abstract

Neuropsychological assessment is frequently used to aid in the differential diagnosis of dementia. In support of this practice, previous investigators have found distinguishable patterns of deficit on neuropsychological tests in patients with dementia syndromes resulting from different neuropathology. A key distinction proposed is one between the patterns of deficit seen in patients with temporo-parietal cortical dementias (e.g. Alzheimer's disease) versus those with frontal-subcortical dementias (e.g. Huntington's disease). However, research addressing the correspondence of neuropsychological test data to specific anatomical markers of dysfunction has not been conclusive. This study addressed the validity of interpreting neuropsychological test data as indicators of neuropathology, specifically evaluating the ability to distinguish between fronto-subcortical and non-frontal cortical patterns of deficit. Comparison of five models in a confirmatory factor analysis did not find an adequate fit for models based upon anatomical systems of dysfunction, and a cluster analysis found two naturally existing groups reflecting differences in general cognitive ability. Recommendations for future research addressing the cortical versus subcortical distinction are made.