Presence of co-morbid substance use disorder in bipolar patients worsens their social functioning to the level observed in patients with schizophrenia

Bipolar disorder has been considered to have a better prognosis than schizophrenia at the very beginning of its definition. However, psychosocial functioning may vary not only because of the characteristics of the disorder, but also of co-morbid conditions, especially regarding substance use disorder (SUD). The purpose of this study was to compare the social adjustment level of patients with bipolar disorder with that observed in patients with schizophrenia, taking into account substance use disorder (SUD). Forty subjects with schizophrenia and 40 subjects with bipolar disorder, in the stable phase of the disorder, were matched for age, gender and presence of SUD (DSM-IV criteria). The social adjustment scale was completed with socio-demographic and clinical characteristics of illness. The global adaptation score of bipolar patients with SUD was poorer than bipolar patients without SUD, but was not observed as being significantly different from that of patients with schizophrenia, with or without associated SUD. Suicide attempts, poor compliance, longer hospitalisation, shorter remissions and criminal activity were also more frequently observed in the group of patients with bipolar disorder and SUD. Presence of substance use disorder seems to have a greater weight than the main diagnostic (schizophrenia versus bipolar disorder) to predict worse social adjustment and poorer outcome.