Apolipoprotein E4 Frequencies in a Japanese Population with Alzheimer's Disease and Dementia with Lewy Bodies

Background: The apolipoprotein E (APOE) epsilon 4 allele has been reported to be a risk factor for Alzheimer's disease (AD) and dementia with Lewy bodies (DLB). Previous neuropathological studies have demonstrated similar frequencies of the APOE epsilon 4 allele in AD and DLB. However, the few ante-mortem studies on APOE allele frequencies in DLB have shown lower frequencies than post-mortem studies. One reason for this may be inaccuracy of diagnosis. We examined APOE genotypes in subjects with AD, DLB, and a control group using the latest diagnostic criteria and MRI, SPECT, and MIBG myocardial scintigraphy. Methods: The subjects of this study consisted of 145 patients with probable AD, 50 subjects with probable DLB, and a control group. AD subjects were divided into two groups based on age of onset: early onset AD (EOAD) and late onset AD (LOAD). All subjects had characteristic features on MRI, SPECT, and/or myocardial scintigraphy. Results: The rate of APOE4 carrier status was 18.3% and the frequency of the epsilon 4 allele was 9.7% in controls. The rate of APOE4 carrier status and the frequency of the epsilon 4 allele were 47% and 27% for LOAD, 50% and 31% for EOAD, and 42% and 31% for DLB, respectively. Conclusion: The APOE4 genotypes in this study are consistent with previous neuropathological studies suggesting accurate diagnosis of AD and DLB. APOE4 genotypes were similar in AD and DLB, giving further evidence that the epsilon 4 allele is a risk factor for both disorders.