Despite the well-known influence of ovarian hormones on the brain and widespread use of hormonal contraception (HC) since the 1960s, our knowledge of HCs cognitive effects remains limited. To date, the cognitive findings have been inconsistent. In order to establish what might make HC studies more consistent, we surveyed the literature on HCs and cognition to determine whether studies considered HC formulation, phase, pharmacokinetics, duration, and gene interactions, and assessed whether oversight of these factors might contribute to variable findings. We found that synthetic HC hormones exert dose-dependent effects, the day of oral contraceptive (Pill) ingestion is critical for understanding cognitive changes, and gene-cognition relationships differ in women taking the Pill likely due to suppressed endogenous hormones. When these factors were overlooked, results were not consistent. We close with recommendations for research more likely to yield consistent findings and be therefore, translatable.
Funding Agencies|Wilfred and Joyce Posluns Chair in Womens Brain Health and Aging from the Posluns Family Foundation; Canadian Institutes of Health Research (CIHR); Ontario Brain Institute; Alzheimer Society of Canada [WJP-150643]; CIHR Masters Award; Ontario Graduate Scholarship; Jacqueline Ford Gender and Health Fund