Cannabis use and abstention in first-episode psychosis: the participants'view

Preventive interventions targeting cannabis use and related harms in people with psychosis: A systematic review

AIM

While most users will not experience severe adverse health outcomes from cannabis, it can be associated with negative outcomes in people with psychosis. People with psychosis who use cannabis have more severe psychiatric symptoms, higher rates of hospitalization, and diminished psychosocial functioning compared to those who do not use cannabis. Most studies of people with psychotic disorders have focused on cannabis use treatments and only a few on preventive interventions for cannabis. This systematic review aims to evaluate the effectiveness of preventive interventions focusing on cannabis use for people with psychosis.

METHODS

We searched CINAHL Plus, EBM reviews, EMBASE, MEDLINE, PsycInfo and PubMed databases for controlled studies assessing the effects of preventive interventions on cannabis use and related harms in people with psychosis. We conducted the search using a combination of the following concepts: cannabis, psychosis, intervention and prevention. Risk of bias was assessed.

RESULTS

The search yielded 11 460 unique studies. Of these, five studies met our eligibility criteria. None of the studies demonstrated clear efficacy of prevention interventions in reducing cannabis use, and none measured cannabis-related harms. All studies had high risk of bias.

CONCLUSION

The small number of studies and the considerable risk of bias made it difficult to conclude whether any of the existing interventions were promising. With increased acceptance and accessibility of cannabis due to liberalizing cannabis policies, it is imperative to improve the evidence base for preventive interventions, in particular their effectiveness in decreasing the risk of cannabis-related harms in people with psychosis.

Reasons for cannabis use in first-episode psychosis: does strength of endorsement change over 12 months?

BACKGROUND

Why patients with psychosis use cannabis remains debated. The self-medication hypothesis has received some support but other evidence points towards an alleviation of dysphoria model. This study investigated the reasons for cannabis use in first-episode psychosis (FEP) and whether strength in their endorsement changed over time.

METHODS

FEP inpatients and outpatients at the South London and Maudsley, Oxleas and Sussex NHS Trusts UK, who used cannabis, rated their motives at baseline (n=69), 3 months (n=29) and 12 months (n=36). A random intercept model was used to test the change in strength of endorsement over the 12 months. Paired-sample t-tests assessed the differences in mean scores between the five subscales on the Reasons for Use Scale (enhancement, social motive, coping with unpleasant affect, conformity and acceptance and relief of positive symptoms and side effects), at each time-point.

RESULTS

Time had a significant effect on scores when controlling for reason; average scores on each subscale were higher at baseline than at 3 months and 12 months. At each time-point, patients endorsed 'enhancement' followed by 'coping with unpleasant affect' and 'social motive' more highly for their cannabis use than any other reason. 'Conformity and acceptance' followed closely. 'Relief of positive symptoms and side effects' was the least endorsed motive.

CONCLUSIONS

Patients endorsed their reasons for use at 3 months and 12 months less strongly than at baseline. Little support for the self-medication or alleviation of dysphoria models was found. Rather, patients rated 'enhancement' most highly for their cannabis use.