An epidemiological study of season of birth, mental health, and neuroimaging in the UK Biobank

Abstract

AbstractEnvironmental exposures during the perinatal period are known to have a long-term effect on adult physical and mental health. One such influential environmental exposure is the time of year of birth which affects the amount of daylight, nutrients, and viral load that an individual is exposed to in the key developmental period. Here we investigate associations between season of birth (seasonality), four mental health traits (n=135,541) and multi-modal neuroimaging measures (n=33,815) within the UK Biobank. Summer births were associated with probable recurrent Major Depressive Disorder (β=0.024,pcorr=0.048), greater mean cortical thickness in temporal and occipital lobes and in the middle temporal, fusiform, superior temporal, and lingual gyri regions (β range=0.013 - 0.020,pcorr<0.05). Winter births were associated with greater white matter integrity globally, in the association fibers, thalamic radiations, and six individual tracts (β range=-0.010 to -0.021,pcorr<0.05). Results of sensitivity analyses that adjusted for birth weight were similar, with additional associations found between winter birth and frontal, occipital and cingulate lobe surface areas, as well as fractional anisotropy in the forceps minor. Sensitivity analyses also revealed an additional association between summer birth and greater cingulate thickness. Overall, results suggest that seasonality affects brain structure in later life and may have a role in lifetime recurrent Major Depressive Disorder. The small effect sizes observed here warrant further research to validate the results in the context of different latitudes and co-examine genetic and epigenetic measures to potentially reveal informative biological pathways.