Rates and Predictors of Conversion to Schizophrenia or Bipolar Disorder Following Substance-Induced Psychosis
Research output: Contribution to journal › Journal article › Research › peer-review
OBJECTIVE: The authors investigated the rates of conversion to schizophrenia and bipolar disorder after a substance-induced psychosis, as well as risk factors for conversion.
METHOD: All patient information was extracted from the Danish Civil Registration System and the Psychiatric Central Research Register. The study population included all persons who received a diagnosis of substance-induced psychosis between 1994 and 2014 (N=6,788); patients were followed until first occurrence of schizophrenia or bipolar disorder or until death, emigration, or August 2014. The Kaplan-Meier method was used to obtain cumulative probabilities for the conversion from a substance-induced psychosis to schizophrenia or bipolar disorder. Cox proportional hazards regression models were used to calculate hazard ratios for all covariates.
RESULTS: Overall, 32.2% (95% CI=29.7-34.9) of patients with a substance-induced psychosis converted to either bipolar or schizophrenia-spectrum disorders. The highest conversion rate was found for cannabis-induced psychosis, with 47.4% (95% CI=42.7-52.3) converting to either schizophrenia or bipolar disorder. Young age was associated with a higher risk of converting to schizophrenia. Self-harm after a substance-induced psychosis was significantly linked to a higher risk of converting to both schizophrenia and bipolar disorder. Half the cases of conversion to schizophrenia occurred within 3.1 years after a substance-induced psychosis, and half the cases of conversion to bipolar disorder occurred within 4.4 years.
CONCLUSIONS: Substance-induced psychosis is strongly associated with the development of severe mental illness, and a long follow-up period is needed to identify the majority of cases.
Original language | English |
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Journal | The American Journal of Psychiatry |
Volume | 175 |
Issue number | 4 |
Pages (from-to) | 343-350 |
ISSN | 0002-953X |
DOIs | |
Publication status | Published - 2018 |
- Adult, Age Factors, Bipolar Disorder/chemically induced, Cannabis/adverse effects, Comorbidity, Denmark, Disease Progression, Female, Humans, Male, Mental Disorders/diagnosis, Middle Aged, Prevalence, Proportional Hazards Models, Psychoses, Substance-Induced/diagnosis, Psychotropic Drugs/adverse effects, Risk Factors, Schizophrenia/chemically induced, Young Adult
Research areas
ID: 218178121