The Effects of Oral Contraceptive Use on Objective and Subjective Episodic Memory

Abstract

Introduced more than 60 years ago, oral contraceptives (OC) are one of the most common forms of contraceptives used by reproductive-aged women today. Despite their widespread use, very little is known about the ways in which the hormones contained in OCs (i.e., synthetic versions of estradiol and progesterone) affect cognition, with much of the literature having been criticized for its predominance of cross-sectional designs, inconsistent consideration of OC-related factors (e.g., pill formulation, reproductive history/previous hormonal contraceptive use, group heterogeneity, etc.), and variable characterization and measurement of cognitive domains. Some studies have suggested that OC use may slightly enhance verbal episodic memory (i.e., our long-term, explicit recollection of personal events), although findings are mixed. It also remains unclear whether OC use alters subjective perceptions of one’s memory. Across three studies, this dissertation addresses the extent to which OC use might influence objective and subjective memory. I begin by describing the development and validation of the neuropsychological methods used in the second half of this thesis. Next, I cross-sectionally examine differences in subjective and objective memory between OC users and non-users. Finally, this thesis culminates with a quasi-experimental, repeated-measures investigation of objective and subjective memory changes in newly initiated OC users. We first tested the reliability of the Multifactorial Memory Questionnaire (MMQ)—a widely-used measure of subjective memory—for use with healthy young adults. Confirmatory factor analysis (CFA) with age invariance testing conducted with n = 408 young and n = 327 older adults suggested that although the MMQ is more reliable in older adults, it is also adequate for use in younger populations. Next, we piloted the remotely-administered, web-based implementation of a well-established episodic memory battery in n = 50 young adults and checked the feasibility of two parallel battery versions for repeated online testing. Additionally, using (young female participant only) data from a previous study employing a similar web-based battery, CFA was used to verify relationships between individual memory tasks in the battery and replicate its factor structure. The final study employed the measures verified above to systematically investigate the role of OC use in objective and subjective memory while addressing common methodological limitations in the literature. Cross-sectional analyses revealed slightly higher objective memory and memory satisfaction among OC users (n = 60) compared to non-users (n = 75); these results were also dependent on parallel task version and participants’ first language. Repeated measures analyses assessing group-by-time interactions, however, indicated no significant changes in objective or subjective memory in newly initiated OC users (n = 37) following three months/cycles of use, compared to long-time OC users (n = 43) and non-users (n = 45). Findings from the present dissertation shed light on the existing mixed evidence on the involvement of OCs in cognitive functioning and suggest that influences on memory may emerge following more prolonged exposure to OC hormones. Notably, this thesis also provides preliminary support for a possible role of contraceptives in subjective memory, particularly satisfaction with everyday memory functioning. Potential implications of our findings for the growing field of contraceptives and cognition research, including methodological considerations, underlying mechanisms of OC influences on cognition, and future research directions are discussed.