Background: Studies of weight gain in DMPA users have shown mixed results with most showing weight increase however the mechanism of weight gain with DMPA remains unknown. Functional magnetic resonance imaging (fMRI) provides an important tool for investigating brain regions associated with food motivation.
Objective: The primary objective is to examine changes in activation of food motivation centers in the brain after DMPA administration.
Study Design: This prospective experimental pilot study examined the effects of DMPA on food motivation centers utilizing fMRI in eight non-obese, ovulatory subjects. Blood oxygen level dependent (BOLD) signal was measured using fMRI while subjects viewed images of high calorie foods, low calorie foods, and non-food objects. fMRI of the brain was performed prior to subjects receiving DMPA 150mg IM and 8 weeks after DMPA. fMRI data was analyzed using the FMRIB Software Library (FSL). Changes in adipokine (leptin, ghrelin) levels and fat mass on DEXA imaging were also measured.
Results: There was a greater BOLD signal response in brain regions associated with food motivation (anterior cingulate gyrus, frontal medial cortex) measured 8 weeks after DMPA between high calorie and low calorie foods than that measured before DMPA (z>2.3, clustered corrected) No statistically significant change was detected in adipokine levels or fat mass during the study period.
Conclusion: This novel study is the first to utilize fMRI to examine the cerebral response to food stimuli after DMPA contraception. Analysis of differences in food motivation may guide the development of interventions to prevent weight gain in DMPA users.