Several studies have shown that cannabis use can induce the development of psychotic episodes in adolescents and is associated with a greater risk of suffering from a psychotic disorder in adulthood. Starting consumption at an early age, ie before the age of 16, would also be an important risk factor.
Starting from these premises, the Canadian Research Team on Cannabis and Psychosis investigated the genetic, neurodevelopmental, clinical and behavioral aspects of the link between cannabis use and the development of psychosis. with the aim of proposing interventions that would make it possible to prevent this pathology. As part of the Acfas Congress, which took place this week, doctoral student Roxane Assaf presented the preliminary results obtained so far.
A first study conducted by this group of researchers from different Canadian institutions consisted in calculating the “polygenic risk score”, that is to say the genetic predisposition to psychosis, of a large cohort of adolescents. The researchers then observed that adolescents with a high score were more likely to use cannabis and develop psychotic episodes.
Another study found thinning of the cerebral cortex in boys who smoked cannabis in the past year. It has also been noted that adolescents who will become future consumers have a thicker cortex, which suggests that “there could be structural predispositions to consumption”, indicated Roxane Assaf, who is a doctoral student in biomedical sciences in psychiatry at the Department of Psychiatry and Addiction of the University of Montreal.
In another large study bringing together more than 3,800 young people, who were followed annually from the age of 13 to 17, data was collected in particular on the possible prepsychotic symptoms they were experiencing: “We asked them if they sometimes heard voices, if they happened to see something that wasn’t there, or if they sometimes felt like someone was following them. The researchers observed that about 8% of these adolescents followed an increasing trajectory, in the sense that they had a moderate level of psychotic symptoms that increased over time.
These same young people then took part in neurocognitive tests, as well as a structural and functional neuroimaging session. These examinations revealed alterations in regions of the brain involved in the processing of emotions, as well as in an area involved in differentiating between oneself and others. These changes were very similar to those also found in individuals with schizophrenia.
“That doesn’t mean that everyone on this increasing risk trajectory will develop schizophrenia, but they are at higher risk,” Ms.me Assaf while indicating that we will verify whether cannabis consumption affects these individuals more given their predisposition.
Sleep and anxiety
In yet another study, anxiety was identified as a possible mediator of the relationship between the frequency of cannabis use and the development of psychotic episodes in girls. Consumers reported more anxiety, and this association with anxiety seemed to lead to psychotic episodes more often, Ms.me Assaf. “But these are only associations that we have observed,” she warns.
In a longitudinal study that continued over five years, it was demonstrated that sleep also plays a mediating role. The researchers found that the more cannabis people use, the more sleep problems they experience the next year, and the more psychotic experiences they report.
These observations “suggest that sleep and anxiety could be targets of intervention to prevent the development of psychosis in people who consume”, indicated the doctoral student.
The group of researchers plan to examine synaptic activity, that is to say the way neurons in the brain communicate with each other, in young cannabis users.
Several centers, including the University of Montreal, recruit university students whose use of cannabis and other substances, as well as various traits, such as anxiety and depression, will be documented. Some of them will then be invited to participate in early cognitive-behavioral interventions aimed at their substance use or aimed at preventing the development of psychotic disorders in those at higher risk. Then, in the future, these individuals will undergo neuroimaging examinations to assess the effect of these interventions on the brain.
The effects of synthetic cannabinoids
Synthetic cannabinoids (CS) are increasingly present in drug seizures around the world. They have become a real public health problem in Europe and the United States, because they have a much stronger effect than cannabis. As part of the Acfas Congress, two students from the University of Quebec at Trois-Rivières (UQTR) drew a portrait of these psychoactive substances that are claiming more and more victims in Canada.
Unlike phytocannabinoids, such as tetrahydrocannabinol (THC), which are derived from plants like cannabis, synthetic cannabinoids are made in the laboratory through chemical synthesis. It was first the pharmaceutical industry that applied itself to synthesizing a molecule having the same biochemical activity as THC, but without its undesirable effects. “Nabilone is an example of a synthetic cannabinoid that is used in the medical community to treat chemotherapy patients,” said Audrey-Anne Matte, a student at 1er university cycle in forensic science at UQTR.
This medical use has likely made these substances more accessible for those who want to use them recreationally, noted his colleague Mérédith Chayer.
CS is usually sold as a smoking herbal blend and is marketed under common names, such as Spice or K2. They are often vaporized on cannabis leaves or on a mixture of dried herbs.
Like the ingredients in cannabis, CS acts on cannabinoid receptors that are present throughout the body. However, they are much more potent than cannabis, and therefore more dangerous. “They induce complete activation of cannabinoid receptors in the nervous system, while THC only partially activates them. Consumed in combination with marijuana, the CS will increase the effect of the latter, and will therefore accentuate the desired effect”, specifies Mme Matte.
However, this combination can cause various health problems, and sometimes death, she points out. “The list of effects [possibles qui ont été recensés] is long: seizures, convulsions, delirium, hallucinations, psychosis, tachycardia, stroke, myocardial infarction, etc. They vary depending on the dose and concentration that has been ingested, as well as the predisposition of the person. »
As new analogues with different chemical structures appear every year, it becomes difficult to predict the toxicological and pharmacological properties of these new compounds, she adds.
According to the data consulted by the two students, the SCs do not seem to represent here, for the moment, such a serious problem as in our neighbors to the South. “But we must remember that we are not actively looking for this type of drug in Canada,” said Ms.me Chayer.
To reduce the impact of these molecules on our population, the two students suggest that SC detection analyzes be carried out when dried plant material or consumer accessories are seized. They also recommend screening for CS in biological tissues (blood, urine) during arrests for impaired driving, for example, to find out if CS has been consumed.