A neurochemical theory of appetite and weight changes in depressive states

The literature concerning appetite and weight changes in depressive illness is reviewed. Diminished appetite and weight loss have for about 100 years been regarded as prominent symptoms of depressive illness. A tendency for some depressives to gain weight has also been recognized. About 85% of depressives lose weight and 15% gain weight. There appears to be a tendency for weight gain to be commoner in milder depressions. Carbohydrate craving is also described in association with some depressed states. The neurochemical control of appetite in health is surveyed. Norepinephrine appears to be necessary for the intake of food, and drugs which raise intrasynaptic levels of norepinephrine stimulate feeding. Serotonin seems to be associated with satiety and in experimental animals decreased intrasynaptic levels of serotonin produce carbohydrate hunger. The neurochemical control of appetite is discussed in relation to the amine theories of depression. A number of hypotheses are drawn from this discussion.