Prevalence and correlates of cognitive asymmetry in a large sample of Alzheimer's disease patients.

Previous research has suggested that a significant minority of patients with Alzheimer's disease (AD) exhibit asymmetric cognitive profiles (greater verbal than visuospatial impairment or vice versa) and that these patient subgroups may differ in demographic and other characteristics. Prior studies have been relatively small, and this investigation sought to examine correlates of asymmetry in a large patient sample (N = 438). Patients were classified into the following cognitive profile groups: low verbal, symmetric, and low visuospatial. Consistent with past research, 28.3% of participants were classified as having asymmetric cognitive profiles, with more participants in the low visuospatial subgroup. Low visuospatial participants were younger than members of the other subgroups, and low verbal participants performed worse on a measure estimating premorbid verbal intelligence. Findings regarding apolipoprotein E (ApoE) ε4 genotype were equivocal, although results provided some evidence for an effect of the ɛ4 allele on cognitive asymmetry. These results suggest systematic differences between neuropsychological asymmetry profiles that support the possibility of distinct subgroups of the disease.