In recent years,a considerable number of epidemiological investigations and animal studies have confirmed that metabolic diseases, such as obesity,type 2 diabetes mellitus and metabolic syndrome, have adverse effects on brain functions,inducing mood disorders and cognition impairment. Brain dysfunctions induced by obesity and related complications are associated with numerous central abnormalities,involving brain shrinkage and neurotrophic function impairment,brain insulin resistance, brain oxidative stress,and brain leptin resistance,as well as dysfunctioned dopamine motivation and the reward system. Moreover,these brain dysfunctions are mediated by several peripheral factors, such as triglycerides/free fatty acids,proinflammatory cytokines,and corticosterone/glucocorticoid. On the other hand,metabolic disturbances correlated with emotional-cognitive disorders are evident,but the mechanisms remain obscure. Because of the drawbacks of animal models, the majority of researches focus on the impact of mental stress on the metabolism of lipid and glucose. The interrela?tionship between metabolic diseases and brain functions has become one of the hot spots for research. In this review,we mainly discussed the potential mechanisms underlying mood disorders and cognition impairment induced by obesity and related complications.