Cannabis link to depression
SMOKING cannabis as a teenager could increase the risk of depression in adulthood by almost 40 per cent, a study by Oxford University has found.
Researchers warned that use of the drug in adolescence may be responsible for about 60,000 cases of depression in subsequent decades – around one in 14 of all cases.
They urged parents to be stricter about teenage use of cannabis, warn- ing that some of the strains being pushed today were 10 times as strong as the drugs of 30 years ago.
And they said cannabis could affect the development of adolescent brains, with “devastating” consequences.
The research examined 11 major studies involving more than 23,000 individuals from adolescence until their 30s. It found that those who tried
cannabis in their teens had a 37 per cent higher risk of depression between ages 18 and 32, and more than three times the risk of attempting suicide.
Scientists said it suggests that if all young people avoided cannabis, around 7 per cent of depression cases in the next 20 years could be prevented.
They called on ministers to prioritise prevention of drug taking, warning that damage caused by cannabis was now a significant public health risk.
Prof Andrea Cipriani, from the University of Oxford, said: “It’s a big public health and mental health problem. The number of people who are exposed to cannabis, especially at this vulnerable age, is very high and I think this should be a priority.”
The study with Mcgill University is the largest meta-analysis in the field. It included teenagers who had used cannabis at least once before the age of 18 and did not distinguish between the frequency of use.
In England, about four per cent of those aged 11 to 15 are estimated to have used the drug within the last month.
Researchers said the findings, published in JAMA Psychiatry, suggest a need for renewed campaigning about the dangers of drug use in adolescence.
Animals studies have suggested a link between exposure to cannabinoids, the active component of cannabis, and the onset of depressive symptoms in adulthood. The studies were observational, meaning they could not prove that use of the drugs triggered later depression, researchers said. It is possible that those who were struggling in adolescence were more likely to turn to drugs, they said.
Dr Gabriella Gobbi, of Mcgill University, said teenagers often thought cannabis was safe because it was derived from plants.
“It’s very important to inform adolescents about the risk and about the kinds of cannabis they use,” she said.
It comes as the Royal College of Psychiatrists reviews its opposition to the legalisation of cannabis.
Prof Sir Robin Murray of the Institute of Psychiatry Psychology & Neuroscience, King’s College London, said the study appeared robust, but had limitations.
“Information about the patterns of cannabis use in the original studies being re-examined is not very detailed; for example they do not quantify the amount of cannabis or what kind is being used. We know from studies that the risk is much greater with daily use of modern, high-potency cannabis than old fashioned low-thc varieties.”