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What’s pushing cannabis use in first-episode psychosis?


 

FROM SIRS 2020

The desire to feel better is a major driver for patients with first-episode psychosis (FEP) to turn to cannabis, new research shows.

An analysis of more than 1,300 individuals from six European countries showed patients with FEP were four times more likely than their healthy peers to start smoking cannabis in order to make themselves feel better.

The results also revealed that initiating cannabis use to feel better was associated with a more than tripled risk of being a daily user.

These findings could be used to help tailor treatment interventions, as well as offer an opportunity for psychoeducation – particularly as the reasons for starting cannabis appear to influence frequency of use, study investigator Edoardo Spinazzola, MD, Institute of Psychiatry, Psychology, and Neuroscience at King’s College London, said in an interview.

Patients who start smoking cannabis because their friends or family partakes may benefit from therapies that encourage more “assertiveness” and being “socially comfortable without the substance,” Dr. Spinazzola said, noting that it might also be beneficial to identify the specific cause of the psychological discomfort driving cannabis use, such as depression, and specifically treat that issue.

The results were scheduled to be presented at the Congress of the Schizophrenia International Research Society 2020, but the meeting was canceled because of the coronavirus pandemic.

Answering the skeptics

Previous studies suggest that cannabis use can increase risk for psychosis up to 290%, with both frequency of use and potency playing a role, the researchers noted.

However, they added that “skeptics” argue the association could be caused by individuals with psychosis using cannabis as a form of self-medication, the comorbid effect of other psychogenic drugs, or a common genetic vulnerability between cannabis use and psychosis.

The reasons for starting cannabis use remain “largely unexplored,” so the researchers examined records from the European network of national schizophrenia networks studying Gene-Environment Interactions (EU-GEI) database, which includes patients with FEP and healthy individuals acting as controls from France, Italy, the Netherlands, Spain, United Kingdom, and Brazil.

The analysis included 1,347 individuals, of whom 446 had a diagnosis of nonaffective psychosis, 89 had bipolar disorder, and 58 had psychotic depression.

Reasons to start smoking cannabis and patterns of use were determined using the modified version of the Cannabis Experiences Questionnaire.

Results showed that participants who started cannabis to feel better were significantly more likely to be younger, have fewer years of education, to be black or of mixed ethnicity, to be single, or to not be living independently than those who started it because their friends or family were using it (P < .001 for all comparisons).

In addition, 68% of the patients with FEP and 85% of the healthy controls started using cannabis because friends or family were using it. In contrast, 18% of those with FEP versus 5% of controls starting using cannabis to feel better; 13% versus 10%, respectively, started using for “other reasons.”

After taking into account gender, age, ethnicity, and study site, the patients with FEP were significantly more likely than their healthy peers to have started using cannabis to feel better (relative risk ratio, 4.67; P < .001).

Starting to smoke cannabis to feel better versus any other reason was associated with an increased frequency of use in both those with and without FEP, with an RRR of 2.9 for using the drug more than once a week (P = .001) and an RRR of 3.13 for daily use (P < .001). However, the association was stronger in the healthy controls than in those with FEP, with an RRR for daily use of 4.45 versus 3.11, respectively.

The investigators also examined whether there was a link between reasons to start smoking and an individual’s polygenic risk score (PRS) for developing schizophrenia.

Multinomial regression indicated that PRS was not associated with starting cannabis to feel better or because friends were using it. However, there was an association between PRS score and starting the drug because family members were using it (RRR, 0.68; P < .05).

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