Visuospatial dysfunction in Alzheimer's disease

Alzheimer's Disease (AD) is a dementing disorder that affects over 4 million Americans. Whereas cognitive losses in AD have been well documented, we have hypothesized that there is an individual variability in the type and severity of decline as AD progresses. This study was undertaken to separate verbal from visuospatial decline in AD, and possibly identify subgroups of the AD population that preferentially retain verbal or visuospatial abilities. The widely used Mini-Mental State Exam (MMSE) was utilized because it tests both verbal and non-verbal skills. The MMSE's of 62 AD patients were retrospectively examined and classified based on performance of the visuospatial task, drawing intersecting pentagons. Pentagon performance was impaired through a wide range of overall scores, but no clear subgroups emerged. Inability to draw the pentagons correctly lowered the overall score by an average of 2 points, while those unable to attempt the pentagons were likely to score 10 or below. This evidence supports our theory that visuospatial ability may decline early in the course of AD and correlate with verbal skills. This information is of clinical significance in monitoring and counseling patients, and assists in understanding the fundamental neurobiology of AD.