by An analysis of numerous studies on cannabis use found that between 2% and 21% of users experienced psychotic symptoms after consuming cannabis. The highest rates were recorded in experimental studies using tetrahydrocannabinol (THC), while the lowest (2%) were observed in studies using medical cannabis. The study was published in Nature Mental Health.
Cannabis is a genus of plants that includes three species: Cannabis sativa, Cannabis IndicaAnd Cannabis sativa. It is known for its psychoactive and medicinal properties, which are mainly due to compounds such as THC (tetrahydrocannabinol) and CBD (cannabidiol). Cannabis is used both recreationally and medicinally, and has effects ranging from relaxation and euphoria to pain relief and anxiety reduction. The legal status of cannabis varies greatly around the world. In some regions, its use is permitted, in others it is strictly prohibited.
In some people, cannabis use can lead to the development of psychotic symptoms, known as cannabis-associated psychotic symptoms. These symptoms can include hallucinations, delusions, and disorganized thinking, especially in people with a predisposition to mental health problems. High doses of THC, the primary psychoactive component of cannabis, are more likely to trigger these symptoms. While some people experience these effects temporarily, in certain cases cannabis use can trigger or worsen long-term psychotic disorders such as schizophrenia.
Study author Tabea Schoeler and her colleagues sought to integrate the results of various studies on cannabis-related psychotic symptoms to better understand how common and under what conditions they occur. They point out that due to increasingly liberal cannabis policies worldwide, this information is crucial to prevent the harmful effects of cannabis use. Another important trend is the increasing concentration of THC in cannabis products over time, which has stronger psychoactive properties compared to CBD.
The researchers searched three scientific databases – PubMed, Embase and Psychinfo – and found 20,428 possible texts. After excluding those that did not meet the inclusion criteria, the analysis was carried out on 162 studies with a total of 210,283 participants.
These studies can be divided into four categories: observational research, evaluations of medical cannabis products, experimental studies with THC administration, and quasi-experimental studies (which compare situations of cannabis use with non-use by observing people using cannabis on their own initiative or not). The vast majority of study participants were from observational research; 16% were involved in studies evaluating medical cannabis; experimental studies included just under 1% of participants, while quasi-experimental studies included only 0.2%.
Of these studies, 99 reported data on cannabis-related psychotic symptoms. These included 41 observational studies (involving 92,888 cannabis users), 19 experimental studies using THC administration (754 participants), and 79 studies evaluating the efficacy and tolerability of medical cannabis products (32,821 participants). In medical cannabis studies, the products were most commonly used to treat pain and cancer. Participants in observational and experimental studies were predominantly in their 20s and 30s, while the average age of people in the medical cannabis evaluation studies was 48 years.
The results showed that the reported percentage of participants who developed cannabis-related psychotic symptoms varied widely between studies, with the proportion being highest in experimental studies at around 21%, highest in observational studies at 19%, and lowest in medical cannabis evaluation studies at 2%.
People more likely to develop cannabis-related psychotic symptoms include those who have received THC, people with pre-existing mental health problems, people with higher dopamine activity, younger people, and women.
The study provides valuable insight into the psychotic symptoms that can develop as a result of cannabis use. However, it is important to note that the experimental studies that showed the highest rates of psychotic symptoms administered THC – the cannabis component known for its powerful psychoactive properties – while studies that showed lower rates likely used other forms of cannabis with much lower THC concentrations.
Authors of the paper “Assessing rates and predictors of cannabis-associated psychotic symptoms across observational, experimental and medical research” are Tabea Schoeler, Jessie R. Baldwin, Ellen Martin, Wikus Barkhuizen and Jean-Baptiste Pingault.
