Grow High: Neurobiological Consequences Of Cannabis Use In Adolescents

Approximately one in five Canadian teenagers consume cannabis (19% of Canadians 15 to 19 years of age), and its recent legalization across the country warrants investigation into the consequences of this use in the developing brain. Adolescence is associated with the maturation of cognitive functions, such as working memory, decision making and the control of impulsivity. This is a highly vulnerable period for brain development, since it represents a critical period in which a regulatory connection is established between the higher order regions of the cortex and the deeper emotional processing circuits within the brain. It is a period of strong remodeling, which makes adolescents highly vulnerable to developmental disorders related to drugs. The research presented by Canadian neuroscientists Patricia Conrod, Steven Laviolette, Iris Balodis and Jibran Khokhar at the Canadian Neuroscience Meeting of 2019 in Toronto on May 25 presented recent discoveries about the effects of cannabis on the adolescent brain.

Dr. Patricia Conrod, from the University of Montreal, studied the interannual changes in alcohol and cannabis use and cognitive function in a sample of adolescents that consists of 5% of all students who entered secondary school in 2012 and 2013 in the Greater Montreal region (a total of 3,826 7th grade students). The students were evaluated annually for 4 years for the consumption of alcohol and cannabis, and their cognitive function was assessed by computerized cognitive tests. The researchers found that the use of substances is linked to low cognitive functioning, a finding that could be indicative of a common underlying vulnerability. Cannabis use was related to deficiencies in working memory and inhibitory control, which is required for self-control. Cannabis use was also linked to deficits in memory recall and perceptual reasoning. Alcohol consumption was not related to deficiencies in these cognitive functions, suggesting that cannabis could have more long-term effects than alcohol.

More recently, Dr. Conrod's team analyzed the difference of sex in the response to cannabis in the same sample of adolescents. Preliminary data indicate that cannabis use had a stronger effect on the memory functions of male students than on women. However, both sexes were equally affected by cannabis in inhibitory control. These results help identify groups of at-risk youth and target them for intervention and early information.

Dr. Steven Laviolette presented an investigation on the effect of the main psychoactive component of cannabis, delta-9-tetrahydrocannabinol or THC, in the brain of adolescents, in animal models of rodents. His team showed that exposure of adolescents to THC induces changes in a specific region of the brain called the prefrontal cortex (PFC) and in a brain circuit, the mesolimbic pathway, which closely resembles the abnormalities seen in schizophrenia. In addition, exposure to THC in adolescents also caused affective and cognitive abnormalities, including deficits in social interactions, memory processing, and regulation of anxiety.

Interestingly, Dr. Laviolette's team discovered that the administration of drugs that restore normal CFP function in early adulthood could reverse the effects of THC exposure in adolescents. They also demonstrated that co-administration of THC with drugs that prevent THC-induced disruption in brain signaling pathways prevented the development of effects similar to schizophrenia. These results offer information on ways to prevent or reverse cerebral signaling defects induced by THC in adolescents.

By: Preeti Narula

Content: https://www.sciencedaily.com/releases/2019/05/190526135747.htm