By Sara Freeman, medwireNews Reporter

Quitting cannabis appears to improve medication adherence in the long-term among patients admitted for first-episode psychosis (FEP), researchers have found.

They also report that this may be particularly important in patients who are hospitalized involuntarily.

“Our results suggest that cannabis use and its withdrawal could be a mediator of adherence in FEP patients,” say Ana González-Pinto (Hospital Santiago, Vitoria, Spain) and colleagues in BMC Psychiatry. The researchers note that stopping using cannabis might improve medication adherence and potentially clinical and functional outcomes.

González-Pinto and colleagues studied 98 individuals, aged an average of 29.8 years, admitted to a general hospital psychiatric ward for FEP. Patients were assessed via a battery of psychiatric tests at admission and at annual follow-up over an 8-year period.

Adherence was determined by self-report via the Morisky–Green test. At baseline, 73% of patients were identified as having bad adherence to their medication, including all of those who had been involuntarily admitted and 46.7% of those using cannabis.

The percentage of patients using alcohol, cannabis, or other substances decreased throughout the study to 57%, 29%, and 16%, respectively, by the end of the 8-year period. At the same time, the percentage of patients with good adherence increased from 26% at baseline to 51%. Of these patients, only 12.8% continued to use cannabis.

According to multiple logistic regression analysis, patients who never used or stopped using cannabis during follow-up were 8.79 times more likely to improve from bad to good adherence, after taking into account type of first admission.

Similarly, treatment adherence improved 5.65-fold among patients who were admitted involuntarily rather than voluntarily, after accounting for cannabis use.

“Our findings imply that FEP patients with coexisting cannabis use are more likely to be nonadherent to medication and should be a target for interventions aimed at both stopping substance use and improving adherence,” say González-Pinto and colleagues.

“Such efforts include involuntary admissions and may result in improved clinical outcomes and patient functioning although further studies are needed.”

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