Abstract
People with depression, bipolar disorder, and schizophrenia manifest considerable cognitive deficits and impairments in everyday functional outcomes. The severity of current mood symptoms is associated with the severity of cognitive deficits in people with unipolar and bipolar disorder, but impairments are clearly still present in cases with minimal current mood symptoms. In people with schizophrenia, depression is less strongly associated with cognitive deficits on a cross-sectional basis, and some evidence suggests that depression and cognitive impairments are inversely related. Furthermore, in schizophrenia, mood symptoms seem to affect everyday functioning in a way that is unassociated with the severity of deficits in cognition and functional capacity. In contrast, in bipolar disorder, mood symptoms seem to affect real-world functioning through an adverse effect on the ability to perform critical functional skills. In both mood disorders and schizophrenia, depression appears to impact the motivation to perform potentially reinforcing acts, possibly through the induction of anhedonia. Clearly, depression has a major adverse impact on everyday functioning in all variants of severe mental illness, and improving its recognition (in the case of schizophrenia) and management has the potential to reduce the adverse impact of severe mental illness on everyday functioning. Reducing disability has the potential to have positive impacts in multiple objective and subjective aspects of functioning in severe mental illness.