A systematic review of the impact of oral contraceptives on cognition.

Combined oral contraceptives (OCs) are the most commonly prescribed medication in women of reproductive age, but despite widespread use, their effect on cognitive performance remains controversial. Given strong evidence for the neurological impact of reproductive hormones, a clear rationale for investigation exists. This systematic review sought to identify, collate and critically appraise studies assessing the impact of OCs on cognition in healthy premenopausal women. Ovid MEDLINE, PsychINFO and EMBASE were comprehensively searched using relevant keywords for original peer-reviewed observational studies or randomised trials published after 1960. Of 1289 references screened, 22 studies were eligible for inclusion. Assembled evidence supports a cognitive impact of OCs restricted to specific domains; however, the quality of evidence is poor. The most consistent finding is improved verbal memory with OC use. Evidence is also emerging that differing progestin androgenicity may lead diverse OC formulations to differentially impact certain cognitive domains, such as visuospatial ability. At present, evidence is inconclusive, contradictory and limited by methodological inconsistencies. There is scope for further research in this area to definitively determine the cognitive impact of OCs.