The role of reward sensitivity in obesity and its association with Transcription Factor AP-2B: A longitudinal birth cohort study.

ABSTRACT

OBJECTIVE: One factor potentially contributing to obesity is reward sensitivity. We investigated the association between reward sensitivity and measures of obesity from 9-33 years of age, paying attention to the inner structure of reward sensitivity. METHODS: The sample included both birth cohorts (originally n = 1176) of the Estonian Children Personality Behaviour and Health Study. The association between reward sensitivity and measures of obesity was assessed using mixed-effects regression models. Associations at ages 9 (younger cohort only), 15, 18, 25 and 33 (older cohort) years were analyzed by one-way ANOVA. The indirect effect of the gene encoding transcription factor 2 beta (TFAP2B) on obesity through reward sensitivity was tested using mediation analysis. RESULTS: According to linear mixed effects regression models, an increase in scores of Insatiability by Reward and both of its components, Excessive Spending and Giving in to Cravings, significantly increased body weight, body mass index, sum of five skinfolds, waist circumference, hip circumference and waist-to-height ratio from 15 to 25 years of age. Findings were similar at age 9 and 33 years. In contrast, no association between obesity and Openness to Rewards or its facets was observed. The TFAP2B genotype was also associated with fixation to rewards in females, but not with striving towards reward multiplicity. CONCLUSION: Our results suggest that reward sensitivity is associated with obesity by its reward fixation component. The heterogeneity of the reward sensitivity construct should be taken into account in studies on body composition.