Shared and dissociable features of apathy and reward system dysfunction in bipolar I disorder and schizophrenia

Background Bipolar disorder I (BD-I) is defined by episodes of mania, depression and euthymic states. These episodes are among other symptoms characterized by altered reward processing and negative symptoms (NS), in particular apathy. However, the neural correlates of these deficits are not well understood. Methods We first assessed the severity of NS in 25 euthymic BD-I patients compared with 25 healthy controls (HC) and 27 patients with...