The course and concomitants of depression in first-episode schizophrenia spectrum disorders: A 24-month longitudinal study

•Depressive symptoms are prominent during the acute phase of illness.•Only a few patients require additional antidepressant medication.•Depressive symptoms are associated with better insight and poorer quality of life. Depressive symptoms are common in schizophrenia and have been associated with both favourable and unfavourable outcomes. We studied the longitudinal course of depressive symptoms and explored their temporal relationships with other manifestations of the illness and its treatment. This longitudinal cohort study included 126 antipsychotic naïve or only briefly treated patients with first-episode schizophrenia spectrum disorders treated with a long-acting antipsychotic over 24 months. Depressive symptoms were assessed at three monthly intervals using the Calgary Depression Scale for Schizophrenia and changes over time were assessed using linear mixed-effect models for continuous repeated measures. Depressive symptoms were most prominent at baseline with highly significant reductions during the first three months of treatment and maintenance of improvement thereafter. Most improvement occurred with antipsychotic treatment alone, with few patients requiring additional antidepressants. We also found that depressive symptoms were associated with positive symptoms, better insight and poorer quality of life, but not with negative symptoms, extrapyramidal symptoms, substance use or cumulative antipsychotic dose.There were few differences between patients who met criteria for depression during the acute phase of treatment and those in the post-acute phase.