The interlocking pentagon drawing test, a part of the Mini-Mental State Examination (MMSE), is a widely used clinical practice to measure visuoconstructional ability of dementia patients. We investigated the anatomical structures of brain associated with pentagon drawing in subjects with mild to moderate Alzheimer's disease (AD) by using voxel-based morphometry (VBM).

Medical records of forty-four AD patients were reviewed and a 1.5 T SPGR 3D image data were used for VBM analysis. A voxel-based multiple regression analysis was used to investigate correlation between gray matter loss and pentagon drawing performance of AD patients. The correlations between pentagon drawing score and MMSE score were evaluated by Spearman correlation analysis.

There was a positive correlation between the interlocking pentagon copying scores and the MMSE scores ( r =0.448, p =0.002). The lower the scores of interlocking pentagon copying were, the more severe the atrophy of right inferior frontal gyrus became ([x, y, z]=[52, 39, 3], Broadmann area 45, and z score=3.86).

The performance of interlocking pentagon drawing is associated with a general cognitive function in patients with mild-to-moderate Alzheimer's disease. It is also associated with the atrophy of the right inferior frontal gyrus.