The antipsychotic olanzapine, which has been associated with weight gain, appears to enhance reward systems in the brain that respond to food, according to a study published online in the Archives of General Psychiatry. Data from magnetic resonance imaging before and after a one-week treatment with olanzapine showed enhanced activations in the inferior frontal cortex, striatum, and anterior cingulate cortex to the anticipation of a food reward. Also seen was a decrease in activation in the lateral orbital frontal cortex, an area of the brain thought to exercise inhibitory control on feeding.
These brain changes were associated with significant increases in weight, food consumption, and disinhibited eating among 25 subjects receiving olanzapine.

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