Cortical thickness is associated with different apolipoprotein E genotypes in healthy elderly adults

Previous studies have consistently suggested that the epsilon 4 allele of apolipoprotein E (APOE) gene is a major risk factor for Alzheimer's disease (AD). However, whether the epsilon 2 allele, a possible protective factor for AD, will express its protective effect in terms of cortical thickness in healthy elderly carriers is unclear. The goal of this study is to clarify the effects of APOE genotypes on cortical thickness in nondemented elderly subjects. We used 164 healthy, cognitively normal, elderly subjects, who were grouped into epsilon 2 carriers, epsilon 3 homozygotes, and epsilon 4 carriers respectively. The APOE epsilon 2 carriers had a significant thicker (corrected p < 0.05)cortical thickness in the superior temporal cortex compared with the epsilon 3 homozygotes. In addition to this area, the APOE epsilon 2 carriers had a significantly thicker region in the dorsolateral prefrontal cortex (corrected p < 0.05) than did the epsilon 4 carriers. These findings suggest that the different alleles of the APOE gene have distinct neuroanatomic effects in elderly healthy subjects and may play specific roles in the development of AD. (C) 2010 Elsevier Ireland Ltd. All rights reserved.