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Season of birth and the risk of dementia in the general population: A long‐term, prospective cohort study
Author(s) -
Mooldijk Sanne S,
Licher Silvan,
Vinke Elisabeth J,
Vernooij Meike W,
Ikram M. Kamran,
Ikram M. Arfan
Publication year - 2020
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1002/alz.042448
Subject(s) - dementia , season of birth , hazard ratio , rotterdam study , medicine , prospective cohort study , population , proportional hazards model , demography , cohort study , incidence (geometry) , cohort , confidence interval , pediatrics , gerontology , disease , psychiatry , environmental health , physics , sociology , optics
Abstract Background Environmental exposures early in life are important for shaping brain development. Season of birth as a proxy for these exposures has been associated with the risk of brain diseases in adolescence and mid‐life, such as schizophrenia and depression. We investigated the link between season of birth and risk of dementia. We further explored underlying structural pathways by studying the link with brain changes on MRI. Method Within the Dutch prospective population‐based Rotterdam Study, we assessed dementia incidence in 12,964 persons born between 1887 and 1960. We used Cox proportional hazard models to determine the relationship between season of birth with incident dementia, and Alzheimer’s disease (AD), with summer births as reference. In addition, we compared dementia incidence among participants born in a cold winter compared to those born in a normal winter. All models were adjusted for age and sex, and additionally for education, ethnicity, income, APOE‐ε4 genotype, cardiovascular risk factors and depressive symptoms. Furthermore, we examined the association between season of birth with volumetric and microstructural integrity markers on brain MRI in 5,436 dementia‐free participants. Result During 26 years of follow up, 1,633 participants developed dementia, of whom 1,282 had AD. The risk of dementia in both winter and fall born participants was higher than those born in summer (Figure 1, age and sex adjusted hazard ratio (HR) 1.14 [95% confidence interval (CI) 1.00‐1.40] and 1.17 [1.02‐1.34], respectively), with stronger effect sizes for AD (1.24 [1.06‐1.45] and 1.23 [1.05‐1.45], respectively). In addition, we found a higher risk for participants born in a cold or very cold winter HR 1.08 [0.88‐1.34] and 1.14 [0.87‐1.48], respectively, compared to those born in a normal winter. Further adjustment did not change these associations. We did not find an association between season of birth and any of the brain imaging markers measured in late life. Conclusion In this western European population of community‐dwelling individuals, winter and fall births are associated with a higher incidence of dementia, especially of AD. We did not find evidence for changes in structural and microstructural brain markers as an underlying mechanism.