Neurosyphilis with complex partial status epilepticus and mesiotemporal MRI abnormalities mimicking herpes simplex encephalitis

Background: The risk effect of APOE e4 allele for Alzheimer's disease is acknowledged, whereas the putative protective effect of e2 allele remains in debate.Objectives: To investigate whether those inconsistent findings may be attributable to differences in age and sex composition of the study populations.Methods: A community dementia free cohort (n = 985) aged >75 years was followed up to detect Alzheimer's disease cases (DSM-III-R criteria).Data were analysed using Cox models with adjustment for major potential confounders.Results: Over a median 5.6 year follow up, Alzheimer's disease was diagnosed in 206 subjects.Compared with APOE e3/e3 genotype, the relative risk (RR) of Alzheimer's disease was 1.4 (95% confidence interval (CI), 1.0 to 2.0; p = 0.03) for heterozygous e4 allele and 3.1 (95% CI, 1.6 to 5.9) for homozygous e4 allele.The association between e4 allele and Alzheimer's disease risk was stronger in men than in women (RR related to the interaction term e4 allele by sex, 0.4; 95% CI, 0.2 to 0.9).The e4 allele accounted for one third of Alzheimer's disease cases among men, but only one tenth among women.The e2 allele was related to a reduced Alzheimer's disease risk mainly in people aged ,85 years (RR, 0.4; 95% CI, 0.2 to 0.8).The RR of Alzheimer's disease related to the interaction term of e2 allele by age was 2.4 (95% CI, 1.0 to 6.0; p = 0.06). Conclusions:The APOE genotype specific effects on Alzheimer's disease vary by age and sex, in which the e4 allele has a stronger risk effect in men, and the e2 allele confers a protective effect only in younger-old people.www.