If you’re among the millions of Americans who use cannabis to ease anxiety, depression or post-traumatic stress disorder (PTSD), a recent study suggests you may want to reconsider.
The largest review to date examined both the safety and effectiveness of medicinal cannabis in mental health conditions. Its conclusion is that there is no evidence that it works for these common uses. The analysis, published in The Lancet – one of the world’s most prestigious medical journals – is drawn from 54 randomized controlled trials conducted around the world over 45 years.
About 27% of people aged 16 to 65 in the US and Canada report using cannabis medicinally. Nearly half of them say they are using cannabis to manage mental health symptoms.
Dr. Jack Wilson of the Matilda Center at the University of Sydney in Australia led the research team. He says the following in a Summary Among the findings:
“Although our paper did not specifically address this, regular use of medicinal cannabis may cause more harm than good by worsening mental health outcomes, for example greater risk of psychotic symptoms and development of cannabis use disorder, and delaying access to more effective treatments.”
Studies have found some limited evidence that cannabis may help some other conditions, including cannabis dependence, autism, insomnia, and tics or Tourette syndrome. But Wilson cautioned that this evidence is also weak:
“The overall quality of evidence for other conditions such as autism and insomnia was low. In the absence of strong medical or counseling support, the use of medicinal cannabis is rarely justified in these cases.”
Where Cannabis Shows More Potential
The news is not entirely negative. Researchers point to evidence that medicinal cannabis may help reduce seizures in some forms of epilepsy, reduce muscle stiffness or spasms in people with multiple sclerosis, and manage specific types of pain.
And there is more nuance in the findings on substance-use disorders. Cannabis-based treatments have shown some promise in helping people with cannabis dependence, such as how methadone treats opioid addiction.
But when used to treat cocaine-use disorder, it actually increases cravings and can worsen that particular addiction.
The American Medical Association and other major medical organizations have raised concerns about the limited regulation and uncertainty surrounding cannabis products. The study could trigger calls for stricter monitoring.