Neurohormonal Correlates of Altered Eating Behaviour in Depressive Disorders

Depression and obesity are widespread, significant global public health concerns. Weight and appetite disturbances are common symptoms of Major Depressive Disorder that can complicate treatment and prognosis and, similarly, obesity increases vulnerability to depression. Proposed shared etiologies for depression and elevated body weight include altered stress perceptions and eating behaviours, as well as neurohormonal mediation. The latter includes altered hypothalamic-pituitary-adrenal (HPA) axis activity, and changes in hunger and satiety signals, adding further evidence to phenotype overlap. There are few investigations on eating behavior, weight changes, and HPA axis alterations in depression. The aim of this series of interlinked investigation was to examine the influence of stress and of food ingestion on hormones involved in appetite regulation along side HPA axis activity. Cortisol, ghrelin, and leptin secretory response to two physiological challenges, i.e., psychosocial stress, and food, was evaluated in eighteen patients with clinical depression, and seventeen matched healthy controls. Neurocognition, eating behavior, and stress perception measures were obtained. In response to the stress challenge, depressed participants exhibited elevation of leptin levels in comparison to controls. Such elevation was influenced by the chronicity of illness. No differences between patients with depression or controls were found in cortisol or ghrelin response to either set of experiments. However, among the participants, emotional eaters exhibited significantly lower levels of ghrelin in response to food. In addition, significant associations between leptin and cognition were noted. Results suggest possible alteration in appetite regulation in both depressed and emotional eaters. It is suggested that appetite and weight increase often seen in chronic depression may be in part be mediated by HPA axis leptin interactions. Potential alterations in feedback systems regulating appetite may be suggested as leading to increased vulnerability for future weight gain in depression.Ph.D