People With Psychosis Had Stronger Negative Feelings About Cannabis but Used It Anyway | Research

The takeaway

Schizophrenia patients and healthy controls had similar implicit (automatic) negative associations toward cannabis, but patients had stronger explicit negative expectations yet continued using, suggesting relaxation expectancies drive use despite knowing the risks.

Read this if you treat patients with psychosis who use cannabis despite understanding the risks.

Relaxation expectancies predicted cannabis use more than negative awareness in both groups

What the researchers found

Seventy patients with recent-onset psychotic disorder and 61 healthy controls with varying cannabis use levels were tested on both implicit (automatic) and explicit (conscious) associations toward cannabis.

Surprisingly, there were no differences in implicit associations between patients and controls. Both groups showed strong negative implicit associations toward cannabis.

However, patients scored significantly higher on explicit negative affect expectancies, meaning they were more consciously aware of negative consequences of cannabis use.

Despite this, explicit relaxation expectancies were the strongest predictors of actual cannabis use and craving in both groups. The expectation that cannabis would help them relax appeared to override their negative associations.

The finding that users had strong negative implicit associations suggested they were engaging in a behavior they did not implicitly "like."

Why it matters

Understanding why schizophrenia patients continue using cannabis despite knowing it worsens their illness could improve treatment approaches. The dominance of relaxation expectancies suggests targeting these specific beliefs in therapy.

The numbers in context

70 psychotic disorder patients, 61 healthy controls. Both groups showed strong negative implicit cannabis associations. Patients had stronger explicit negative expectations. Explicit relaxation expectancies were the strongest predictor of use and craving.

How the study worked

Cross-sectional study using three Single-Category Implicit Association Tests (relaxed, active, negative) and an explicit expectancy questionnaire in 70 patients with recent-onset psychotic disorder and 61 healthy controls with varying cannabis use levels.

What this study cannot tell us

Cross-sectional design. Implicit measures may not capture all aspects of automatic processing. The study cannot determine whether relaxation expectancies drive use or are post-hoc justifications. Different levels of cannabis use between groups may confound comparisons.

How to read the evidence

Cross-sectional study using validated implicit and explicit measures. Moderate sample sizes. Cannot establish causal direction between expectancies and use.

When this study was published

Published in 2010. Expectancy-based approaches to understanding cannabis use in psychosis have continued to develop.

The bigger picture

This study challenges the assumption that cannabis users with psychosis lack insight into the harm. They know cannabis is harmful (strong explicit negative associations) but use it anyway because the expectation of relaxation overrides their awareness of risk.

Questions still open

Would therapeutic interventions targeting relaxation expectancies reduce cannabis use in psychosis? Can alternative relaxation strategies replace the cannabis use motivation? Do implicit associations change with treatment?

Common questions

Why do people with psychosis use cannabis if they know it is harmful?

This study found that the expectation of relaxation from cannabis was a stronger motivator than awareness of harm. People may use cannabis for immediate relief of tension or distress despite knowing about longer-term negative consequences.

What are implicit associations?

Implicit associations are automatic, often unconscious reactions that can be measured with reaction-time tests. They may differ from what people consciously report. In this study, both users and non-users showed implicit negative associations toward cannabis, suggesting the behavior conflicts with automatic attitudes.

Read the original research

Implicit and explicit affective associations towards cannabis use in patients with recent-onset schizophrenia and healthy controls.

Psychological medicine, 40(8), 1325-36

View on PubMed ↗Publisher’s paper ↗

Citation

Dekker, N; Smeerdijk, A M; Wiers, R W; Duits, J H; van Gelder, G; Houben, K; Schippers, G; Linszen, D H; de Haan, L. (2010). Implicit and explicit affective associations towards cannabis use in patients with recent-onset schizophrenia and healthy controls.. Psychological medicine, 40(8), 1325-36. https://doi.org/10.1017/S0033291709991814