Experts are warning parents not to be complacent about the risks of teenagers using cannabis. Researchers from the UK and Canada have found robust evidence to show that using the drug in adolescence can increase the risk of developing depression in adulthood by 37%.

Cannabis use in the young is an important public health issue, particularly given that the drug available today tends to be much stronger than it was previously, say the researchers from the University of Oxford and Montreal’s McGill University. The developing brain is particularly susceptible, they say, and their findings should act as a warning to families who consider cannabis use as part of the growing-up process.

An NUS survey of 2810 students released last year revealed more than half (56%) of students had tried drugs – and two in five said they currently use drugs. Cannabis was by far the most commonly used recreational drug.

Parents need to heed warnings

Report author Professor Andrea Cipriani, NIHR Research Professor of Psychiatry at the University of Oxford, conceded that some parents had a relaxed attitude to the drug, but added the evidence was clear.

“Regular use during adolescence is associated with lower achievement at school, addiction, psychosis and neuropsychological decline, increased risk of motor vehicle crashes, as well as the respiratory problems that are associated with smoking. This is important information for parents and teenagers. The risk is modest, but it can have a devastating impact”, he said.

The researchers looked at 11 previous studies, covering more than 23,000 young people, reports the journal JAMA Psychiatry [1]. The findings showed that cannabis use before 18 years of age increased the chance of an individual developing depression in young adulthood (defined as before the age of 35 years) by 37%.

This means that around one in 14 cases of depression in that age group (around 60,000 in the UK) could be attributed to drug use in the teenage years.

The study also investigated whether there was an association with anxiety and suicide attempts. There was an increased risk of anxiety developing in young adulthood, but it was not considered statistically significant. In addition, those who used cannabis in their teenage years were three times more likely to try to kill themselves; although the data were not considered robust enough to draw a firm conclusion.

Based on the data and what is known about the impact that cannabis has on the developing brain, the researchers could not prove that cannabis use was definitively causing depression. However, they said it looked to be a strong link. Research has suggested that the drug affects the parts of the brain that govern rational and emotional thinking as well as serotonin levels that influence mood.

Drug testing cannabis

Cannabis is highly detectable and can be found in urine, saliva, hair as well as nail clipping samples. AlphaBiolabs’ range of tests for cannabis vary in their windows of detection so recent or chronic use can be established. In addition, ingestion as opposed to environmental exposure can be discerned.

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[1] G. Gobbi et al. Association of cannabis use in adolescence and risk of depression, anxiety and suicidality in young adulthood: A systematic review and meta-analysis. JAMA Psychiatry 2019 DOI: 10.1001/jamapsychiatry.2018.4500