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Visuospatial deficit in dementia of the Alzheimer type
1Department of Psychology, Washington University, St Louis, Mo, USA.
Objective:
To examine visuospatial impairment in a task that minimizes episodic memory demands in individuals with very mild or mild dementia of the Alzheimer type compared with a healthy control group.
Design:
Initial scores on the Visual Form Discrimination Test enrolled in longitudinal studies of dementia of the Alzheimer type and healthy aging.
Setting:
Alzheimer's Disease Research Center at Washington University, St Louis, Mo.
Participants:
Volunteer samples of 59 people (35 women and 24 men) with mild dementia of the Alzheimer type, 66 (39 women and 27 men) with mild dementia of the Alzheimer type, and 146 healthy nondemented individuals (90 women and 56 men) were recruited between 1988 and 1992. Ages ranged from 51 to 96 years. Persons with confounding medical, neurologic, or psychiatric disorders were excluded. Dementia severity was staged by means of the Clinical Dementia Rating.
Main Outcome Measures:
Total number correct on the Visual Form Discrimination Test as well as the numbers of three types of errors: peripheral figure movement or rotation, major figure distortion, and major figure rotation.
Results:
Visuospatial deficit was apparent in very mild dementia of the Alzheimer type. Individuals with both very mild and mild dementia of the Alzheimer type made more errors involving peripheral figures and rotation of a major figure than did healthy, nondemented individuals.
Conclusion:
The initial effects of Alzheimer's disease on cognitive function are more pervasive than just episodic memory failure.