Alcohol Use Disorder and Schizophrenia or Schizoaffective Disorder
Schizophrenia and schizoaffective disorder are schizophrenia spectrum disorders that cause significant disability. People with these schizophrenia spectrum disorders have high rates of co-occurring substance use disorder, including alcohol use disorder (AUD), and it contributes to worse outcomes than for those who do not have co-occurring substance use disorder. This article provides an updated review of the epidemiology, neurobiologic basis of co-occurrence, assessment, and treatment of people with co-occurring AUD and schizophrenia or schizoaffective disorder.
Individuals with these psychotic disorders have three times the risk of heavy alcohol use relative to the general population. One meta-analysis of individuals with schizophrenia found a lifetime prevalence of AUD of 24.3%. One American study reported that 36.4% of 404 participants had experienced AUD before their first episode of psychosis.
Basis of Co-Occurrence
For disorders such as schizophrenia that stem from variation at multiple genetic loci, the various risk alleles can be summed together to determine a polygenic risk score. Strong associations between substance use disorder, including AUD, and the polygenic risk score for schizophrenia indicate that shared genetic liability may contribute to the co-occurrence of these disorders.
Common neurobiological mechanisms, including dysfunction in brain reward circuitry, may explain the high rates of co-occurrence of schizophrenia and AUD or other substance use disorders.
There are various theories and hypotheses on the co-occurrence of schizophrenia spectrum disorders and AUD. These include,
- diathesis-stress model – the combined interaction of a neurobiological vulnerability (i.e. genetic risk for schizophrenia) with an environmental vulnerability (i.e. adolescent alcohol use)
- self-medication hypothesis – people use substances to find relief from symptoms or in an effort to decrease side effects that arise from antipsychotic treatments
- unifying hypothesis – the co-occurrence of schizophrenia and substance use disorder may relate to a dysregulation of the mesocorticolimbic reward system in the brain
- neurodevelopmental theory, the neonatal ventral hippocampal lesion (NVHL) model – rats receive small, bilateral, hippocampal lesions at the end of the first week of life, and in adulthood they display many of the memory and social deficits associated with schizophrenia. These rats also consume more substances and after access to alcohol in adolescence consume more as adults
Assessment, Treatment, and Prognosis
Treatment for substance-induced psychosis focuses on acute management, often with reduced stimulation, in a supportive, abstinent environment, and sometimes with short-term antipsychotic treatment. Once an individual becomes abstinent and withdrawal has resolved, psychotic symptoms also usually resolve, but 25% of cases may persist, resulting in diagnoses of schizophrenia spectrum disorders. By contrast, treatment for individuals who have primary psychotic disorders with co-occurring AUD usually requires long-term antipsychotic medication and psychosocial interventions, in addition to other interventions for AUD noted in this section. Moreover, for individuals with co-occurring AUD and psychotic disorders, both disorders should be treated simultaneously. Thus, comprehensive treatment—combining medication with behavioral and psychosocial interventions—is appropriate.
Few studies have examined the effects of medications (i.e., naltrexone, disulfiram, and acamprosate) that treat AUD among individuals with psychotic disorders, evidence of the safety and potential benefit is sufficient to encourage increased use in this population. However, no randomized controlled trials of these medications examine alcohol outcomes in people with co-occurring schizophrenia and AUD.
Group therapy using cognitive behavioral therapy, motivational enhancement therapy, or contingency management has a role in treating AUD and co-occurring schizophrenia. Considerations for this particular population include using active and ongoing motivation enhancement approaches and modifying cognitive behavioral therapy to account for cognitive, interpersonal, and motivational deficits that commonly occur among people with schizophrenia.
Future Research Directions
Further research on the etiology of these co-occurring disorders and on treatment of affected individuals is needed.