Treatment with cannabis based medicinal products (CBMPs) can improve the conditions of people living with treatment-resistant depression (TRD), new research shows.
The study, published in the Journal of Affective Disorders, analysed data from 698 patients registered on the UK Medical Cannabis Registry (UKMCR). Researchers observed improvements in patient-reported outcome measures (PROMs), including depression severity, anxiety, sleep quality and health-related quality of life over 24 months.
The cohort of participants consisted of 698 UK patients who were registered on the UKMCR, 71.35% of whom were male and 28.65% female. They had an average age of 37 years and an average BMI of 27.46 (overweight). Despite most of the members of the cohort having jobs in many different sectors, including the armed forces, over 31% were unemployed. 22% had never smoked tobacco, 40% were current smokers, and 38% were ex-smokers.
When asked about their cannabis use, 8% said they had never used, 18% said they were ex-users, and 74% reported being current cannabis users.
At the beginning of the study, the median amount of THC taken by participants was 20mg per day, and the median amount of CBD was 3mg per day. Flower was prescribed to 81.5% of participants, oils to 47.7% of participants, and less than 1% were prescribed capsules and ointments.
Participants completed different sets of PROMs at the start of the trial, and again at 1, 3, 6, 12, 18, and 24 months.
Researchers measured whether patients experienced a “minimal clinically important difference” (MCID) – meaning they felt enough improvement that the change was meaningful to them in their daily lives. At the beginning of the study, 43% of participants reported experiencing this meaningful improvement in their general health, and this increased to 62% at 24 months. For sleep quality, 43% reported meaningful improvement at the start, rising to 57% at 24 months. Similar improvements were observed in other measures.
“Over 24 months of therapy with CBMPs for depression, participants recorded improvement in mood, anxiety, general health-related quality of life, and sleep as measured by validated PROMs,” the study authors wrote. “The proportion of patients reaching MCID demonstrates sustained clinical improvements in depression and associated symptoms. These findings are consistent with other sources of real-world data, which indicate that CBMPs may confer benefits in mood and anxiety in patients with depression.”
The data from the study showed that the greatest results were observed in the first three months of the study, with patients reporting a plateau in the effectiveness of treatment in the following months, a trend that has also been observed in previous studies. The reduction in efficacy can be explained by a tolerance build-up, amongst other factors, the study authors explained: “The observed trajectory may be an example of the therapeutic ceiling effect, reflecting the natural plateau of treatment response over time. There is evidence to suggest that the plateauing observed in this study could also be a result of pharmacological tolerance to the effects of CBMPs, specifically THC, through CB1 receptor desensitisation, as shown in both preclinical and human imaging studies.”
