Cannabinoid use for mental health conditions lacks evidence
31 October, 2019
New research concludes that there is not enough evidence to justify the use of medicinal cannabinoids to improve mental health.
A recent paper on the findings in The Lancet Psychiatry describes how the study, which takes the form of a meta-analysis, combines and analyzes data covering 3,000 people in 83 studies from 1980 to 2018.
The analysis focuses on the effectiveness of cannabinoids in the treatment of six conditions in adults.
"There is scarce evidence to suggest," write the authors, "that cannabinoids improve depressive disorders and symptoms, anxiety disorders, attention deficit hyperactivity disorder, Tourette's syndrome, post-traumatic stress disorder, or psychosis."
The researchers found the evidence to be limited and of a low standard.
They call for high quality studies to examine the various impacts of cannabinoids on people with mental health conditions.
'Be aware of risks and monitor closely'
They conclude that, given the known risks of cannabinoids, the current evidence of their effectiveness does not justify recommending them as mental health treatments.
The team did find low quality evidence, however, that pharmaceutical tetrahydrocannabinol (THC) can improve anxiety symptoms in people with other conditions, such as multiple sclerosis or chronic pain.
"Our findings have important implications in countries where cannabis and cannabinoids are being made available for medical use," says lead study author Louisa Degenhardt, Ph.D., a professor at the University of New South Wales, in Australia, and deputy director its National Drug & Alcohol Research Centre.
She predicts that countries that permit the use of medicinal cannabinoids will likely see a rise in demand for such use.
Prof. Degenhardt suggests that doctors and people seeking mental health treatment need to recognize the risks of using cannabinoids and be aware that current evidence of their effectiveness is limited.
"Those who decide to proceed," she adds, "should be carefully monitored for positive and negative mental health effects of using medicinal cannabinoids."
Medicinal use increasing worldwide
Humans have used the cannabis, or marijuana, plant medicinally for thousands of years.
However, it was only in the 1990s that scientists discovered the endocannabinoid system and how its interaction with plant-derived and synthetic cannabis compounds, or cannabinoids, can affect the brain.
There are around 100 or more cannabinoids that can interact with the endocannabinoid system. The two major ones are delta-9-tetrahydrocannabinol, or THC, and the less potent cannabidiol (CBD).
The availability and use of medicinal cannabinoids is increasing worldwide, with mental health issues among the most common reasons.
However, this increase is also raising concerns because much research on nonmedical cannabis use has shown that it can increase symptoms of psychosis, depression, and anxiety.
In their study paper, the authors define medicinal cannabinoids — the subject of their investigation — as an umbrella term for medicinal cannabis and pharmaceutical cannabinoids, together with their synthetic derivatives.
Medicinal cannabis use encompasses use of any part of the cannabis plant or extracts, while pharmaceutical cannabinoids are "pharmaceutical-grade medicinal extracts with defined and standardized [THC] with or without CBD."
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