Nearly Half of First-Episode Psychosis Patients Had Substance Use Problems, Mostly Cannabis | Research

The takeaway

Among 357 first-episode psychosis patients, 44% met criteria for substance abuse or dependence, with cannabis being the most commonly used substance alongside alcohol.

Read this if you want to understand how common cannabis use is among people experiencing psychosis for the first time.

44% of first-episode psychosis patients met criteria for substance abuse or dependence

What the researchers found

Researchers examined the first 357 consecutive admissions to a comprehensive early psychosis program in Canada. They found that 44% of patients met diagnostic criteria for substance abuse or dependence at the time they first presented for treatment.

The substances most commonly involved were alcohol and cannabis. The rate of substance misuse in this group was significantly higher than in the general population.

Substance misuse was significantly associated with male gender, younger age, and younger age of onset. These patterns held across different assessment measures including the Positive and Negative Syndrome Scale and the Calgary Depression Scale for Schizophrenia.

Why it matters

First-episode psychosis represents a critical window for intervention. Understanding how common substance use is at this stage, and which substances are most involved, helps clinicians design treatment programs that address both psychosis and substance use simultaneously rather than treating them as separate issues.

The numbers in context

357 consecutive admissions studied. 44% met criteria for substance abuse or dependence. Cannabis and alcohol were the most commonly used substances. Substance misuse was significantly associated with male gender and younger age of onset.

How the study worked

This was a cross-sectional study of the first 357 consecutive admissions to a comprehensive early psychosis program. Patients were assessed using standardized tools including the Positive and Negative Syndrome Scale, Calgary Depression Scale for Schizophrenia, Quality of Life Scale, Case Manager Rating Scale, and Premorbid Adjustment Scale. Substance misuse was assessed using diagnostic criteria for abuse and dependence.

What this study cannot tell us

The cross-sectional design cannot determine whether substance use preceded or followed the onset of psychosis. The study assessed substance use at the time of first presentation, which may not reflect lifetime patterns. The single-site design limits generalizability to other populations and healthcare systems.

How to read the evidence

Cross-sectional study from a single early psychosis program. Provides a snapshot of substance use prevalence but cannot establish timing or causation.

When this study was published

Published in 2004, this study reflects substance use patterns from the early 2000s. Cannabis potency and availability have changed since then.

The bigger picture

The high rate of cannabis and alcohol use among first-episode psychosis patients has been documented across multiple studies in different countries. Whether substance use contributes to the onset of psychosis, emerges as a coping mechanism, or shares common underlying risk factors remains an active area of research. The association with younger onset age is particularly notable for clinical planning.

Questions still open

Does treating substance use alongside psychosis in early intervention programs improve outcomes compared to treating psychosis alone? Are the patterns of substance use in first-episode psychosis different from those seen in later stages of the illness?

Common questions

Was cannabis the most common substance used by first-episode psychosis patients?

Cannabis and alcohol were both commonly used. The study found that the majority of the 44% who met substance misuse criteria used one or both of these substances.

Did substance use cause the psychosis?

This study cannot answer that question. It found a high rate of co-occurrence at the time of first treatment, but the cross-sectional design cannot determine whether substance use preceded or followed psychosis onset.

Read the original research

Substance misuse at presentation to an early psychosis program.

Social psychiatry and psychiatric epidemiology, 39(1), 69-72

View on PubMed ↗

Citation

Van Mastrigt, Sarah; Addington, Jean; Addington, Donald. (2004). Substance misuse at presentation to an early psychosis program.. Social psychiatry and psychiatric epidemiology, 39(1), 69-72.