A 20-year multi-follow-up of hallucinations in schizophrenia, other psychotic, and mood disorders

Background. Hallucinations are a major aspect of psychosis and a diagnostic feature of both psychotic and mood disorders. However, the field lacks information regarding the long-term course of hallucinations in these disorders. Our goals were to determine the percentage of patients with hallucinations and the relationship between hallucinations and recovery, and work attainment. Method. The present study was a prospective evaluation of the 20-year trajectory of hallucinations in 150 young patients : 51 schizophrenia, 25 schizoaffective, 25 bipolar with psychosis, and 49 unipolar depression. The patients were studied at an index phase of hospitalization for hallucinations, and then reassessed longitudinally at six subsequent follow-ups over 20 years. Results. The longitudinal course of hallucinations clearly differentiated between schizophrenia and bipolar disorder with psychosis, and suggested some diagnostic similarities between schizophrenia and schizoaffective disorder, and between bipolar disorder and schizoaffective disorder and depression. Frequent or persistent hallucinatory activity over the 20-year period was a feature of 40-45% of schizophrenia patients. The early presence of hallucinations predicted the lack of future periods of recovery in all patients. Increased hallucinatory activity was associated with reduced work attainment in all patients. Conclusions. This study provides data on the prospective longitudinal course of hallucinations, which were previously unavailable to the field, and are one of the key features of psychosis in major psychiatric disorders. This information on the clinical course of major psychiatric disorders can inform accurate classification and diagnosis.