Severe mental illness (SMI) refers to the most burdensome psychiatric conditions. The need to pre-empt the onset of SMI is pressing because once SMI develops, quality of life is poor and available treatments have limited efficacy. Most risk factors for SMI are either unchangeable (e.g., genetics) or difficult to alter (e.g., low socio-economic status). In contrast, cannabis use is one specific risk factor that could be avoided. Certain individuals are more vulnerable to the harmful effects of cannabis. Genetic factors can help us identify these high-risk individuals. One in three individuals are carriers of a higher-risk genetic variant, and cannabis users with this genotype are at up to 7-fold increased risk of developing schizophrenia. In our study, genetic counselling will be provided to participants by a board-certified genetic counsellor. During the genetic counselling session, participants will have the option to receive their genotype. Participants will be counselled regarding their individualized risk of developing and of not developing SMI based on family history, whether or not they choose to use cannabis, and genotype (if the participants accept the genetic test results). The investigators hypothesize that this intervention will reduce exposure to cannabis compared to the youth who are not offered the intervention.
Name: Genetic counsellingDescription: Participants will receive information on risk/protective factors and causes of mental illness. Participants are not required to receive numeric/genetic risk information. Participants who choose to receive genetic and/or numeric risk information will be counselled on their risk of NOT developing and of developing SMI based on their genetic test results and/or family history information they provide. Risk estimates will be derived by genetic counsellors, according to standard practice guidelines. Participants who receive genetic information will be counselled on the possible influence of cannabis use on risk of mental illness based on their genotype. Participants who choose to not receive genetic information will be counselled on the influence of cannabis on mental health.Type: Behavioral
Description: Self-reported cannabis use on a questionnaire.Measure: Self-reported cannabis use Time: 1 month
Description: Acceptability will be established as the proportion of individuals accepting the offer of intervention.Measure: The proportion of participants who complete the intervention after receiving an offer to participate (intervention acceptability) Time: Completion of study (2 years).
Description: Urine will be screened for the presence/absence of cannabinoids.Measure: Presence of cannabinoids in urine Time: 1 month
There is one SNP
A replicated gene-cannabis interaction shows that carriers of a common genetic variant (C alleles at rs2494732 in the AKT1 gene) are at up to 7-fold increased risk of developing psychosis if they use cannabis.