Season of birth and vulnerability to the pathology of Alzheimer's disease: an in vivo positron emission tomography study

Background: This study used positron emission tomography to examine whether the seasonal birth effect as an exogenic indicator of early life environmental factors influenced vulnerability to Alzheimer's disease (AD) pathology in the elderly. Methods: We analysed datasets from the Alzheimer's Disease Neuroimaging Initiative, which included the data for 234 cognitively normal (CN) individuals and patients with mild cognitive impairment (MCI) (n = 114) and AD dementia (n = 38). As an index of amyloid beta (A beta)/tau accumulation, the F-18-AV-45- and F-18-AV-1451-standardized uptake value ratios (SUVRs) were compared between groups of spring-to-summer births and fall-to-winter births by analysis of covariance. In addition, a multiple linear regression analysis was performed to determine whether the season of birth was a predictor of F-18-AV-45 and/or F-18-AV-1451 SUVRs, for which a difference was observed. Results: Seasonal birth difference was a good predictor of F-18-AV-1451 SUVR. We found that participants with a fall-to-winter birth showed lower F-18-AV-1451 SUVRs than those with a spring-to-summer birth in both the CN and MCI/AD groups, after correcting for the effect of age, sex, years of education, and Alzheimer's Disease Assessment Scale cognitive subscale score, that could possibly affect tau accumulation. Conclusions: Participants with a fall-to-winter birth showed less tau accumulation than those with a spring-to-summer birth after accounting for the factors that could affect tau accumulation. Our findings showed a vulnerability to tau pathology in participants with a fall-to-winter birth, which may be caused by perinatal or postnatal brain damage due to the risk factors associated with the cold season.