Paris (AFP)

Can cannabis and its derivatives relieve people with certain mental illnesses such as depression or psychosis? In the current state of the research, this profit is not demonstrated, concludes an Australian study published Monday.

As a growing number of countries legalize medical cannabis, evidence suggesting that it can improve the condition of patients with mental disorders is "limited" and "insufficient" to warrant a recommendation by health authorities, according to researchers.

To reach this conclusion, they screened 83 studies on the use of cannabis or its active substances, tetrahydrocannabinol (THC) and cannabidiol (CBD), in patients with six psychiatric disorders: depression, anxiety disorder , attention deficit / hyperactivity disorder (ADHD), Tourette syndrome, post-traumatic stress disorder and psychosis.

Some studies show "a small improvement in anxiety symptoms" with THC in patients with other health conditions, such as chronic pain or multiple sclerosis, but it is unclear whether the effect is not linked to an improvement of the disease itself, according to the article, published in the British medical journal The Lancet Psychiatry.

Thirty countries in the world authorize, at different levels, therapeutic cannabis (about twenty European countries, the United States, Australia, Canada, Israel, several countries of Latin America ...).

And, according to the study, mental disorders are one of the most common reasons for this use, after chronic non-cancer pain.

"One of the most striking aspects" with this wave of legalization of cannabinoids for medical purposes "is that in many cases this happens outside the regulatory authorities usually responsible for controlling the development of drugs", says Louisa Degenhardt, lead author of the study, interviewed by AFP.

At the same time, the risks associated with the use of cannabis are proven, she adds, citing the risks of dependence, those related to driving under the influence of these substances and "data showing that people consuming cannabis are more likely to develop depression or psychotic sympyomas. "

The authors point to the need for more quality studies on the subject, including more patients, longer follow-up, and comparing effects with a placebo group.

In the meantime, "we can not develop medical recommendations for their use in mental disorders," says Professor Degenhardt.

And in countries where this use is already legal, "doctors and patients need to be informed about the limited level of existing evidence and the risks of cannabinoids," adds the professor at the National Drug and Alcohol Research Center (University of New South Wales). South, Sydney).

France has given the go-ahead for two years of experimentation with the prescription of therapeutic cannabis, but only for the treatment of pain in certain specific indications and in case of failure of existing drugs.

© 2019 AFP