Resting State Functional Magnetic Resonance Imaging Studies Of Women With Restrained Eating:Binge Eating And Weight Gain Risk

Restrained eater (RE) refers to intentional, sustained restriction of caloric intake to lose or maintain body weight, characterized by continuity, strong motivation, mostly in women, but not very successful weight loss. A large number of studies have shown that RE can be regarded as margins of eating disorders with large number. Such people tend to increase their future risk of binge eating, bulimia nervosa, and weight gain. It is a challenge for those people to lose or maintenance weight through restraining the food intake, especially in the food temptation environment. As such, restrained eating has become the hot topic in obese psychology and management for eating disorders.Based on the existed researches, we have learned that RE increases their future risk of binge eating, bulimia nervosa, and weight gain. So far, although a large number of studies have concerned about this risk and made some theoretical derivation, that is, high sensitivity for food information and low ability of inhibitory control facilitate such risk, few image studies investigate and support these theoretical derivation directly. Resting-state fMRI can be obtained in a task-free condition, which is characterized by the significant low frequency spontaneous fluctuation, reflecting the "baseline" brain activities. This method provide a whole new prospective for neural mechanism in restrained eater. To investigate the possible neural mechanism of risk of binge eating, bulimia nervosa, and weight gain, there studies were conducted:Study 1 investigated resting-state fMRI differences between Restrained Eaters (REs, N=22) and unrestrained eaters (UREs, N=30) using regional homogeneity (ReHo) analysis, which measures the temporal synchronization of spontaneous fluctuations. Samples were equated on body mass index (BMI) and caloric deprivation levels before undergoing fMRI. Compared with UREs, REs showed more ReHo in brain regions associated with food reward (i.e., orbitofrontal cortex (OFC), dorsal-lateral prefrontal cortex (d1PFC)), attention (i.e., lingual gyrus, cuneus, inferior parietal lobule) and somatosensory functioning (i.e., paracentral lobule, anterior insula). In addition, ReHo values for the left d1PFC and left anterior insula, respectively, were negatively and positively correlated with SSRT among REs but not UREs.Study 2 investigated interhemispheric resting-state functional connectivity (RSFC) in restrained eaters using a recently validated approach, voxel-mirrored homotopic connectivity (VMHC). Thus, we examined the difference of VMHC, between female restrained eaters (REs) and unrestrained eaters (UREs) following food deprivation and its association with binge eating tendency. In addition, we analyzed seed-based RSFC associated with areas exhibiting significant different in VMHC. Compared to UREs, REs showed reduced VMHC in dorsal-lateral prefrontal cortex (DLPFC), which is involved in inhibiting hedonic overeating. REs demonstrated decreased RSFC between the right DLPFC and ventromedial prefrontal cortex (VMPFC) and posterior cingulate cortex (PCC). Further, these alterations have a close links with self-reported uncontrollable binge eating only for REs but not UREs.Study 3, resting fMRI was used to test the extent to which spontaneous neural activity in regions associated with inhibitory control and food reward account for potential relations between baseline RE levels and changes in body weight among young women over a one-year interval. Spontaneous regional activity patterns corresponding to RE were assessed among young women using regional homogeneity (ReHo) analysis, which measured temporal synchronization of spontaneous fluctuations within a food deprivation condition. Analyses indicated higher baseline RE scores predicted more weight gain at a one-year follow-up. Furthermore, food-deprived women with high dietary restraint scores exhibited more spontaneous local activity in brain regions associated with the reward value of food [i.e., orbitofrontal cortex (OFC)/ventromedial prefrontal cortex (VMPFC)] and reduced spontaneous local activity in inhibitory control regions [i.e., bilateral dorsal-lateral prefrontal cortex (DLPFC)] at baseline. More notably, the association between baseline RE and follow-up weight gain was mediated by decreased local synchronization of the right DLPFC in particular and, to a lesser degree, increased local synchronization of the right VMPFC. In conjunction with previous research, these findings highlight possible neural mechanisms underlying the relationship between RE and risk for weight gain.The innovations of this study are:(1) the explainations for the risk of binge eating tendency and weight gain in restrained eaters are mainly based on theoritical and empirical deduction, however, the direct evidence for this two risk is relatively rare. So, through our three studies, we found the possible neural explaination and provied the support for goal conflict theory and "cool-hot" model in restrained eaters. (2) previous fMRI studies about restrained eating are focused on task fMRI, but, alternative way resting state fMRI provides whole new prospective. Through the altered baseline activity of brain, we can pridict the binge eating and weight gain in restrained eaters.