Research reveals: Cannabis has not shown significant effectiveness in the treatment of mental disorders

In the last decade, medical cannabis has become one of the common options for treating mental distress, but a comprehensive scientific review recently published presents a much more complex, and sometimes disturbing, picture from which it appears that there is insufficient evidence that cannabis is effective for mental disorders.

The review was conducted by researchers from the University of Sydney, and included an analysis of 54 randomized controlled trials conducted over more than four decades. A total of 2,477 subjects participated in them, most of them men with an average age of 33. This is one of the most extensive attempts to date to examine the effect of cannabis on mental disorders, and it was published in the journal The Lancet Psychiatry.

At the same time, there was also a clear increase in the risk of side effects. According to the data, the chance of such phenomena appearing was approximately 75% higher among patients who received cannabis, compared to those who did not. Among the phenomena that have been reported are impairment of concentration, a feeling of fogginess, worsening of anxiety and even the appearance of psychotic symptoms.

The researchers point out that the routine use of cannabis for the treatment of mental disorders is rarely justified, and warn that the treatment may delay turning to more established treatment options, such as psychological or drug therapy. However, preliminary evidence of a possible effect has been found in several areas, including sleep disorders, Tourette syndrome and certain aspects of the autism spectrum. Even in the treatment of addiction to cannabis itself, a certain effect was noted, but the researchers emphasize that these are limited findings that require further research.

Experts who were not involved in the study point out that the current work faces limitations that were common in previous studies, which were sometimes based on self-reports or observational data only. According to them, this is a more comprehensive attempt to examine the relationship between cannabis and mental health under controlled conditions.

The review also points to limitations. Almost half of the included studies were defined as having a risk of bias, due to design or reporting problems. Meanwhile, the high variability between the types of products, doses and duration of treatment makes it difficult to draw unequivocal conclusions.