Ghrelin modulation of mesolimbic reward circuitry
Difficulty losing weight and maintaining weight loss may be due in part to biological factors which favor increased intake of palatable foods in response to stress. This may include hormones such as ghrelin which act on brain reward regions to signal food reward sensitivity and attainment. In this study, we are examining whether ghrelin is associated with brain activity in response to palatable food and to monetary reward in individuals with depression, a form of chronic stress. An improved mechanistic explanation for the relationship between stress and overeating will potentially inform the design of more effective intervention.
Neurocognitive changes in menopause
Ghrelin is also involved in memory and learning, acting on neurons located in specific brain regions (e.g., hippocampus and amygdala) to stimulate neurogenesis and enhance memory formation and retention. Further, interactions between estrogen and ghrelin suggest that low levels of estrogen after menopause might enhance the impact of ghrelin on brain regions involved in both eating behaviors and cognitive function. In this study, we are examining whether postmenopausal women show relationships between ghrelin and brain activity/structure in regions involving cognition and food intake which vary by BMI. We will also investigate the relationships between ghrelin and cognitive functioning domains of memory and decision-making, and assess whether these relationships vary with BMI status and change over time. Determining the role of ghrelin in these pathways holds promise in identifying potential treatment targets for intervention in obesity and associated cognitive impairment, especially in postmenopausal women for whom this important public health problem is most prevalent.