ABSTRACT
The aim of this study was to evaluate the relationship between severity of dementia and hand dexterity in patients with Alzheimer's disease (AD) using the Purdue Pegboard test including both simple and complex dexterity tasks. Eighty-four patients with AD and 32 non-demented subjects (controls) who were registered in a senior day-care center participated in this study. All of the subjects in this study were right-handed. The AD group consisted of 36 patients with a Clinical Dementia Rating of 1 (CDR 1), 35 with a CDR of 2 (CDR 2), and 13 with the CDR of 3 (CDR 3). For the simple task, right hand scores in the CDR 1, CDR 2, and CDR 3 groups were significantly lower than those of the controls whereas left hand scores were not lower than the controls. While the right hand scores were higher than the left hand scores in the controls and the CDR 1 group, no significant difference was observed between the right and left hand scores in the CDR 2 and 3 groups. Moreover, left hand scores were higher than right hand scores in 19 % of the CDR 1 group, 34% of the CDR 2 group, and 23 % of the CDR 3 group. Differences between right and left hand scores, which is a measure of handedness superiority, were decreased in order from the control group to the CDR 1 group and to the CDR 2 group. There was a relationship between “memory” subscale in the CDR and the differences in right and left hand scores. These results indicated that handedness superiority became unclear or disappeared as memory impairment progressed.