In first-episode psychosis, cigarette smoking was linked to worse cognition and function even after accounting for cannabis use | Research

The takeaway

Among 140 patients with first-episode psychosis, 53% smoked cigarettes, and heavy smokers had later onset of psychosis, worse cognition, and lower functioning than non-smokers, even after adjusting for cannabis use frequency.

Read this if you want to understand how cigarette smoking and cannabis use interact in early psychosis.

53% of first-episode psychosis patients smoked; smoking independently linked to worse cognition

What the researchers found

In 140 patients entering specialized first-episode psychosis treatment, 53% smoked cigarettes: 47 were light/moderate smokers (1-19/day) and 27 were heavy smokers (20+/day). Smoking status was highly associated with cannabis use frequency.

After adjusting for cannabis use, significant differences remained. Heavy smokers were older at program entry and had a later age of psychosis onset. Non-smokers had more education, better neurocognitive performance, and higher functioning than both smoking groups.

These findings suggest that cigarette smoking has independent effects on cognition and function in psychosis, beyond what can be attributed to co-occurring cannabis use.

Why it matters

Previous research on smoking and psychosis often failed to account for cannabis co-use, making it difficult to attribute effects to either substance. By statistically controlling for cannabis, this study shows that cigarette smoking carries its own independent associations with cognitive and functional outcomes in early psychosis.

The numbers in context

140 FEP patients. 53% smoked cigarettes. 47 light/moderate (mean 9.8/day), 27 heavy (mean 26.4/day), 66 non-smokers. Heavy smokers: later psychosis onset. Non-smokers: more education, better cognition, higher functioning. Cannabis use: highly correlated with smoking status.

How the study worked

Cross-sectional analysis of 140 patients entering specialized first-episode psychosis treatment. Divided into non-smokers (n=66), light/moderate smokers (n=47), and heavy smokers (n=27). Analyses adjusted for cannabis use frequency to isolate cigarette-specific associations.

What this study cannot tell us

Cross-sectional design cannot determine causation. Self-reported substance use may be inaccurate. Cannabis use was controlled statistically but not experimentally. The sample may not represent all first-episode psychosis patients. Potential confounders (socioeconomic status, premorbid functioning) may not be fully captured.

How to read the evidence

Cross-sectional observational study with appropriate statistical adjustment for cannabis use. Good design for identifying independent associations.

When this study was published

Published in 2017. Integrated smoking cessation in early psychosis treatment continues to be advocated.

The bigger picture

The extremely high smoking rate in psychosis (53% in this sample, compared to ~15-20% in the general population) is a major health concern. Finding that smoking's negative associations persist after adjusting for cannabis use strengthens the case for integrated smoking cessation as part of early psychosis treatment.

Questions still open

Would smoking cessation in early psychosis improve cognitive and functional outcomes? Does nicotine have specific effects on psychosis neurobiology, or are the associations driven by general health and socioeconomic factors? Would longitudinal studies confirm these cross-sectional findings?

Common questions

Do people with psychosis smoke because of the illness or vice versa?

This study cannot determine the direction. Smoking may be used to self-medicate symptoms, or shared genetic/environmental factors may predispose to both. The high smoking rate (53%) likely reflects multiple contributing factors.

Is cannabis or tobacco worse for psychosis outcomes?

This study found that after controlling for cannabis use, cigarette smoking still had independent negative associations with cognition and functioning. Both substances appear to have distinct effects, suggesting both should be addressed in treatment.

Read the original research

Smoking status and its relationship to demographic and clinical characteristics in first episode psychosis.

Journal of psychiatric research, 85, 83-90

View on PubMed ↗Publisher’s paper ↗

Citation

Grossman, Michael; Bowie, Christopher R; Lepage, Martin; Malla, Ashok K; Joober, Ridha; Iyer, Srividya N. (2017). Smoking status and its relationship to demographic and clinical characteristics in first episode psychosis.. Journal of psychiatric research, 85, 83-90. https://doi.org/10.1016/j.jpsychires.2016.10.022