Substance Misuse in First Episode Psychosis

​Substance misuse is extremely common in first episode psychosis (FEP), worsens virtually every important outcome, and needs fully integrated management rather than being treated as an optional add‑on. The substance most consistently linked to poorer outcomes is cannabis, but alcohol and stimulants are also major contributors.
 
Around 40–50% of people with FEP meet criteria for a current or recent substance use disorder, most often cannabis and alcohol. In one prospective FEP cohort, over half (53%) met criteria for substance misuse during 15‑month follow‑up; cannabis misuse was present in 42% and alcohol in 30%. Young age, male sex, and being single are typical correlates; for cannabis, about 46% of FEP patients in a large London cohort had documented use at presentation.
 
Substance misuse in FEP is associated with more inpatient admissions, longer time in hospital, and higher rates of compulsory admission. Misuse is linked with increased risk and earlier onset of relapse, even after controlling for diagnosis, duration of untreated psychosis, and adherence. Persistent misusers show more positive symptoms, more depressive symptoms, and poorer functional outcomes than those who stop or never misuse, whereas stopping cannabis after FEP clearly improves long‑term outcome.
 
Cannabis use in FEP is associated with higher frequency of hospital admissions, more days in hospital, and a higher likelihood of compulsory detention. Part of this effect appears mediated by antipsychotic treatment failure, indexed by a greater number of different antipsychotics prescribed over time. Continued cannabis use after onset of psychosis increases relapse risk in a dose‑like manner, while discontinuation is associated with better symptom and functional trajectories.
 
Substance misuse can obscure the boundary between primary psychotic disorders and substance‑induced psychosis; longitudinal observation and careful temporal mapping of symptoms vs use are crucial. Comorbid misuse is associated with more aggression, legal problems, poor engagement, and higher rates of non‑adherence to medication and follow‑up. At the same time, a proportion of FEP patients stop substances spontaneously after the episode, underscoring the importance of early psychoeducation and motivational work.
 
Guidelines for early psychosis emphasise that psychosis and substance use must be treated in an integrated fashion within the same team rather than in parallel, fragmented services. Routine, structured assessment of all substances (including tobacco), with collateral history and toxicology where indicated. Psychoeducation for the young person and family about links between substances, relapse, and medication response, delivered early and repeatedly. Motivational interviewing and cognitive–behavioural strategies targeting both psychotic symptoms and substance use, with harm‑reduction goals where abstinence is initially unrealistic. 
 
Careful antipsychotic management (“start low, go slow”), with attention to side‑effect burden that might otherwise drive the person back to substances. Second‑generation antipsychotics are preferred in FEP; long‑acting injectables can be considered to support adherence where substance misuse destabilises oral treatment. For alcohol or other drugs, evidence‑based substance-induced psychosis treatments (e.g., relapse‑prevention medications, structured psychosocial programmes) should be embedded in early psychosis services rather than referred out. Tobacco treatment should be offered proactively; smoking is highly prevalent in FEP and interacts with antipsychotic metabolism (especially clozapine and olanzapine).
 
Overall, comorbid substance misuse is one of the most important modifiable determinants of prognosis in FEP, shaping relapse risk, service use, and functional recovery. The trajectory is not fixed: patients who reduce or stop substances after a first episode move towards outcomes approaching those of non‑users, especially over the long term. For any individual with emerging psychosis, early, assertive, integrated work on substance use should be considered core treatment rather than secondary adjunctive care.
 
References
 
Archie, S., Rush, B.R., Akhtar-Danesh, N., Norman, R., Malla, A., Roy, P. & Zipursky, R.B. (2007, March 3). 33(6):1354-1363. Substance Use and Abuse in First-Episode Psychosis: Prevalence Before and After Early Intervention.Schizophrenia Bulletin.
 
Gonzalez-Pinto, A., Alberich, S., Barbeito, S., Gutierrez, M., Vega, P. et al. (2009, November 13). 37(3):631-639. Cannabis and First-Episode Psychosis: Different Long-Term Outcomes Depending on Continued or Discontinued Use. Schizophrenia Bulletin.
 
NICE Clinical Guidelines, No. 20. (2011). Psychosis with Coexisting Substance Misuse: Assessment and Management in Adults and Young People. Psychosis with Coexisting Substance Misuse. British Psychological Society (UK). 
 
Patel, R., Wilson, R., Jackson, R., Ball, M., Shetty, H., et al. (2016, March). Association of Cannabis Use with Hospital Admission and Antipsychotic Treatment Failure in First Episode Psychosis: An Observational Study. British Medical Journal.
 
Rege. S. (2020, December 16). First Episode Psychosis/Early Psychosis – Key Principles from the Australian Clinical Guidelines for Early Psychosis. Psych Hub Scene. 
 
Schoeler, T., Petros, N. & Di Forti, M. (2016, November). Association Between Continued Cannabis Use and Risk of Relapse in First-Episode Psychosis: A Quasi-Experimental Investigation Within an Observational Study. JAMA Psychiatry.
 
Wisdom, J.P., Manuel, J. I. & Drake, R.E. (2011, September). 62(9):1007-1012. Substance Use Disorder Among People with First-Episode Psychosis: A Systematic Review of Course and Treatment. Psychiatric Services.