The relationship between negative symptoms and depression in schizophrenia: a systematic review

Objective To provide an update on the evidence base for the nature of the relationship between negative symptoms and depressive features in people with schizophrenia, and propose new models that reflect their complex relationship. Method A systematic review following PRISMA guidelines. A total of 2210 articles were identified from EMBASE, PsychInfo and MEDLINE, and further two articles were hand-searched from references. Twenty-seven met inclusion criteria and were included in the review. Results In schizophrenia, primary evidence suggests symptoms of low mood, suicidal ideation and pessimism have more specificity for depression whereas alogia and blunted affect may have more specificity as negative symptoms. Anhedonia, anergia and avolition may be common to both. Conclusion It may be possible to further distinguish depressive features from negative symptoms in schizophrenia when detailed phenomenology is considered. However, in a proposed dimensional model, these two domains continue to share certain phenomena, highlighting their close relationship.