What's Pushing Cannabis Use in First-Episode Psychosis?

Liam Davenport

June 18, 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 1300 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 threefold 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, King's College London, UK, told Medscape Medical News.

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," Spinazzola said.

He noted 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 (SIRS) 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 3.9-fold, with both frequency of use and potency playing a role, the researchers note.

However, they add that "skeptics" argue the association could be due to individuals with psychosis using cannabis as a form of self-medication, the comorbid effect of other psychogenic drugs, or there being 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, UK, and Brazil.

The analysis included 1347 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 vs 5% of controls starting using cannabis to feel better; 13% vs 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 [RRR], 4.67; P < .001).

Starting to smoke cannabis to feel better vs 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 vs 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).

Complex Association

Commenting on the study for Medscape Medical News, Gabriella Gobbi, MD, PhD, professor, Neurobiological Psychiatry Unit, Department of Psychiatry, McGill University, Montreal, Quebec, Canada, said the data confirm "what we already know about cannabis."

She noted that one of the "major causes" of young people starting cannabis is the social environment, while the desire to use the drug to feel better is linked to "the fact that cannabis, in a lot of cases, is used as a self-medication" in order to be calmer and as a relief from anxiety.

There is a "very complex" association between using cannabis to feel better and the self-medication seen with cigarette smoking and alcohol in patients with schizophrenia, said Gobbi, who was not involved with the research.

"When we talk about [patients using] cannabis, alcohol, and cigarettes, actually we're talking about the same group of people," she said.

Although "it is true they say that people look to cigarettes, tobacco, and alcohol to feel happier because they are depressed, the risk of psychosis is only for cannabis," she added. "It is very low for alcohol and tobacco."

As a result, Gobbi said she and her colleagues are "very worried" about the consequences for mental health of the legalization of cannabis consumption in Canada in October 2018 with the passing of the Cannabis Act.

Although there are no firm statistics yet, she has observed that since the law was passed, cannabis use has stabilized at a lower level among adolescents. "But now we have another population of people aged 34 and older that consume cannabis," she said.

Particularly when considering the impact of higher strength cannabis on psychosis risk, Gobbi believes the increase in consumption in this age group will result in a "more elevated" risk for mental health issues.

Spinazzola and Gobbi have reported no relevant financial relationships.

SIRS Congress 2020. Abstract S92.

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