VBM-Studie zum Einfluss endogener sowie exogener weiblicher Sexualhormone auf die zerebrale Morphometrie

Oral contraceptives with combined supplements of estrogen and progesterone are the most popular drugs for contraception nowadays. However, against the background of increasing research on the impact of substituted female hormones on the human brain people become more and more insecure and afraid. Recent studies in the last decades indeed have shown growing evidence for a modulating effect of exogenous as well as endogenous sexual hormones on brain structure. With this in mind, the following work has examined systematically the impact of both endogenous and exogenous steroid hormones on human brain volume via voxel based morphometry (VBM) and surface based morphometry (SBM) to strengthen the scientific foundation against growing insecurities concerning oral contraceptives. In a comparison between 18 naturally cycling women and 18 women taking oral contraceptives it could be shown that there are smaller gray matter volumes in the last-mentioned group, especially in the cingulate gyrus – a part of the limbic system. Furthermore endogenous as well as exogenous fluctuations of hormone concentrations and their effect on brain structure in a longitudinal function have been investigated. There are indications for a volume increase in certain areas of the temporal as well as frontal gyrus and the cingulate gyrus in the pill-intake phase of the test group. Additional to findings of previous studies it could be shown that there are no significant volume changes in brain structure between the early follicular phase (menstruation) and the mid luteal phase of the control group. On that basis the already existing research should be reinterpreted. If there is a detectable volume difference of single areas it has to be searched for between the late follicular cycle phase (ovulation) and another cycle phase. Due to the high estrogen concentration in the late follicular phase as well as the pill-intake phase future research should especially investigate whether estrogen is a determining factor for brain modulation. In that context it is important to focus on the late follicular phase and to stick to a standardized definition and control of the cycle phase, as could be shown in the present study.