Oral contraceptives positively affect mood in healthy PMS-free women: A longitudinal study

Objective: Menstrual cycle phase and oral contraceptives (OC) use influence mood and cognition and these effects may be moderated by the mineralocorticoid receptor (MR) genotype. The effect of menstrual cycle phase on mood may be increased if participants know that this is the focus of study. We assessed aspects associated with reproductive depression such as mood, interpersonal sensitivity, affect lability and depressive cognitions in MR-genotyped OC-users and naturally cycling (NC) women in a carefully masked design. Methods: A homogenous sample of healthy, PMS-free, pre-menopausal MR-genotyped women (n = 92) completed online questionnaires eight times during two consecutive cycles. Results: The masking of the research question was successful. OC-users did not differ significantly from NC women in positive and negative affect at the time of assessment, personality characteristics (e.g. neuroticism) or mental and physical health. Both groups reported more shifts in anger in the first cycle week (p < 0.001; = 0.08). Compared to NC women, OC-users reported fewer mood-shifts between depression and elation in the mid-luteal phase of the menstrual cycle (p = 0.002; eta(2)(p) = 0.10) and had fewer ruminating thoughts at all phases (p = 0.003; eta(2)(p) = 0.11). Effects of MR-genotype were not significant after correction for multiple comparisons. Conclusion: OC users scored more favorably on measures associated with reproductive depression. OC users also showed a decreased affect variability possibly indicating an emotional blunting effect, which is in line with previous reports on affect-stabilizing effects of OC. Limitations were loss of cases due to irregularities in the menstrual cycle length and possible confounding by the 'survivor effect', since almost all OC-users took OC for more than a year.