People with schizophrenia and lifetime cannabis use showed greater deficits in emotional expression and anticipating pleasure | Research

The takeaway

Among 71 adults with schizophrenia, those with lifetime cannabis use history showed greater deficits in emotional expression, anticipatory pleasure, and social functioning compared to non-users.

Psychiatrists treating schizophrenia, psychosocial rehabilitation clinicians, and patients with co-occurring cannabis use and psychosis.

Cannabis users with schizophrenia: worse emotional expression, pleasure, and social function

What the researchers found

Compared to non-using schizophrenia patients (n=36), those with lifetime cannabis use (n=35) expressed less ability to express emotions, were less likely to anticipate pleasure, and had poorer social functioning. Cannabis use moderated the relationship between anticipatory pleasure and prosocial activities, suggesting cannabis disrupts the motivational pathway from expecting reward to engaging socially.

Why it matters

Negative symptoms (flat affect, anhedonia) are the most treatment-resistant aspect of schizophrenia. Finding that cannabis use history worsens these specific deficits suggests cannabis may undermine the very emotional capacities patients need for recovery.

The numbers in context

71 adults with schizophrenia; 35 cannabis users vs 36 non-users; cannabis users: less emotional expression, less anticipatory pleasure, poorer social function; cannabis moderated anticipatory pleasure-prosocial activity link.

How the study worked

Cross-sectional comparison of 71 adults with schizophrenia (35 with lifetime cannabis use, 36 without) using the Emotional Expressivity Scale, Temporal Experience of Pleasure Scale, and Social Functioning Scale.

What this study cannot tell us

Cross-sectional (cannot determine causation); small groups; lifetime use measure does not capture current use, dose, or duration; groups may differ on unmeasured variables; prolonged illness duration in both groups.

How to read the evidence

Moderate: direct comparison of two clinical groups on validated measures, but cross-sectional and small sample.

When this study was published

Published 2020.

The bigger picture

Cannabis is often used by schizophrenia patients to self-medicate. The irony is that while it may temporarily relieve distress, lifetime use appears associated with worsened negative symptoms, the very symptoms that most limit long-term functioning and quality of life.

Questions still open

Does cannabis use cause negative symptom worsening, or do those with worse negative symptoms use cannabis differently? Would CBD (not THC) have different effects on emotional processing in schizophrenia?

Common questions

Does cannabis worsen schizophrenia symptoms?

In this study, schizophrenia patients with lifetime cannabis use had greater deficits in emotional expression, anticipation of pleasure, and social functioning compared to non-users. Cannabis also disrupted the link between expecting pleasure and actually engaging in social activities.

Why do people with schizophrenia use cannabis?

Often to self-medicate anxiety and other distressing symptoms. However, this study suggests that over time, cannabis use may worsen the negative symptoms (flat affect, anhedonia) that most limit quality of life and social recovery.

Read the original research

Individuals with psychosis and a lifetime history of cannabis use show greater deficits in emotional experience compared to non-using peers.

Journal of mental health (Abingdon, England), 29(1), 77-83

View on PubMed ↗Publisher’s paper ↗

Citation

Schnakenberg Martin, Ashley M; Lysaker, Paul H. (2020). Individuals with psychosis and a lifetime history of cannabis use show greater deficits in emotional experience compared to non-using peers.. Journal of mental health (Abingdon, England), 29(1), 77-83. https://doi.org/10.1080/09638237.2018.1487540