Instability of Cognitive Asymmetry in Alzheimer's Disease

Patients with probable Alzheimer's disease (AD) were assessed neuropsychologically three times, at 6-month intervals, to identify those with patterns of performance suggesting hemispheric asymmetry in cerebral degeneration. By two different methods, over half of the patients satisfied liberal criteria for cognitive asymmetry on one or more assessments, but only 12-15% did so on all three visits. This is the proportion expected by chance. The small, stable Low Verbal and Low Spatial groups did not differ from each other, nor from the globally impaired group, on clinical or demographic variables. The Low Spatial patients identified by either method had the earliest age of onset and had shorter durations of illness. Limited autopsy data suggest that AD patients with cognitive asymmetries are more likely to have brain pathology in addition to that typical of AD.