Cannabis smoking in teenage years linked to adulthood depression

https://www.theguardian.com/society/2019/feb/13/cannabis-smoking-in-teenage-years-linked-to-adulthood-depression

Nicola Davis
Wed 13 Feb 2019 11.00 EST
Last modified on Wed 13 Feb 2019 15.50 EST

Scientists believe they have identified about 60,000 cases of depression in adults under 35 in the UK, and more than 400,000 in the US, that could be avoided if adolescents did not smoke cannabis.

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After taking into account factors including age, mental health issues at the outset and socioeconomic status, the results linked cannabis use to a greater likelihood of later developing clinical depression, having suicidal thoughts or making a suicide attempt. The odds of attempting suicide were almost 3.5 times worse among those who used cannabis before the age of 18 than those who did not – although the authors note the figure is imprecise.

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The key psychoactive ingredient of cannabis is THC, or delta-9 tetrahydrocannabinol, which binds to receptors in the brain that are particularly common in regions important for emotion and learning as well as rational thinking. Density of such receptors in these regions peaks during adolescence. That, together with the fact that young people’s brains are still developing, had led to increasing concern about the impact of cannabis on young users, Cipriani said.

The link to depression might be down to the presence of receptors which bound THC in parts of the brain where the neurotransmitters serotonin and noradrenaline were produced, he said.

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While the authors of the study say the apparent effects are of modest size, they stress the impact is far from negligible. By applying the results to the known prevalence of clinical depression among adults under the age of 35, they conclude that one in 14 cases within this age group could be avoided if teenagers did not use the drug.

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the studies began before highly potent cannabis became commonplace.

“We know from studies of psychosis that the risk is much greater with daily use of modern high-potency cannabis than old-fashioned low-THC varieties,” he said.

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tags: drug use, drug abuse