Association between season and cognitive function in adults without cognitive impairment.

Composite global cognitive performance as a function of date of assessment, double plotted. Circles indicate means of 2-month bins. Bars indicate standard errors of the mean. Dotted lines indicate fit cosine curve. p-Value indicates significance of contribution of seasonal rhythmicity to overall variance, calculated as described in the text. (A) Baseline measurements for the Religious Orders Study (ROS) and Rush Memory and Aging Project (MAP) cohorts combined (n = 2,234). (B) Baseline measurements for the Minority Aging Research Study (MARS) cohort (n = 527). (C) Baseline measurements for the combined ROS, MAP, and MARS cohorts considered together (n = 2,761).