Left frontal lobe contributions to concept formation: a quantitative MRI study of performance on the Delis-Kaplan Executive Function System Sorting Test.

This study examined relationships between lobar volumes and performance on the Delis-Kaplan Executive Function System (D-KEFS) Sorting Test, a standardized measure of concept formation. There were 89 participants: 19 patients with probable Alzheimer's disease, 25 patients with frontotemporal dementia, 13 patients with semantic dementia, 12 patients with progressive nonfluent aphasia, 9 patients with probable progressive supranuclear palsy, 2 patients with possible progressive supranuclear palsy, and 9 healthy participants. We used BRAINS2 software to generate volumes of the right and left frontal, temporal, and parietal lobes. Multiple regression analysis indicated that, after controlling for Mini-Mental State Examination scores, intracranial volume, and demographic variables, only the left frontal lobe significantly predicted performance on the D-KEFS Sorting Test.