Association of BACE1 Gene Polymorphism with Cerebellar Volume but Not Cognitive Function in Normal Individuals

Aims: β-Site amyloid precursor protein (APP)-cleaving enzyme 1 (BACE1) is a biological and positional candidate gene for Alzheimer’s disease (AD). Previous studies found that BACE1-null mice had impaired performance on cognition and neurodegeneration during the aging process. Additionally, a synonymous polymorphism of BACE1 (rs638405) in exon 5 has been reported to be associated with risk for AD. We hypothesized that this BACE1 gene variant might influence regional brain volumes and cognitive tests in normal individuals. Methods: Participants were 330 normal volunteers between 21 and 92 years of age (mean age 56.3 ± 22.0 years; 191 males, 139 females). Cognitive tests (the Mini-Mental State Examination and Digit Spans), magnetic resonance imaging, and genotyping of BACE1 rs638405 were examined for each subject. The differences in regional gray matter (GM) volumes between G homozygotes and C-allele carriers were tested using optimized voxel-based morphometry. Results: Compared to C-allele carriers, G homozygotes exhibited significantly larger GM volumes in the left cerebellar culmen and right cerebellar lingual area, but no significant differences on cognitive function tests. Conclusion: The findings suggest that the BACE1 rs638405 polymorphism may affect cerebellar morphology, but not cognitive function in healthy humans.