Apolipoprotein E ε2 genotype delays onset of dementia with Lewy bodies in a Norwegian cohort

BACKGROUND Results conflict concerning the relevance of APOE alleles on the development of dementia with Lewy bodies (DLB), though they are well established in connection with Alzheimer's disease (AD). The role of APOE alleles in a Norwegian cohort of patients with DLB was therefore examined compared with patients with AD and healthy control individuals. METHODS The study included 156 patients with DLB diagnosed according to the consensus criteria guidelines, 519 patients diagnosed with AD according to the National Institute of Neurological and Communicative Diseases and Stroke/Alzheimer's Disease and Related Disorders Association (NINCDS/ARDRA) criteria and 643 healthy elderly volunteers. Patients were recruited through hospitals, outpatient clinics, nursing homes or from local care authorities in central and south-western parts of Norway. Healthy individuals were recruited from caregivers and societies for retired people. RESULTS Subjects carrying an APOE ε2 allele had a reduced risk for developing DLB (OR 0.4, CI 0.3 to 0.8, p=0.004), and the onset of disease was delayed by 4 years (p=0.01, Mann-Whitney U test). Conversely, the APOE ε4 allele increased the risk for development of DLB (OR 5.9, CI 2.7 to 13.0, p<0.0005 for homozygotes). Similar results were found for patients with AD regarding the effect of APOE ε2, though the protective effect appeared to be slightly less pronounced than in DLB. This study is one of the largest regarding DLB and APOE to date. CONCLUSION The results indicate that APOE ε2, a protective factor in AD, has a clear beneficial effect on the development of DLB also.