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Teenage marijuana smokers with mental health disorders are THREE times more likely to self-harm, study warns US researchers studied more than 200,000 teens with mood disorders Found ten per cent of these were diagnose with ‘cannabis use disorder’ This condition linked to 3.28 times higher risk of non-fatal self harm



Teenagers with bipolar disorder or depression who smoke cannabis are at increased risk of death and self-harm, a shock new study has found. 

Mood disorders in adolescence have long been linked with cannabis abuse and this addiction has now been found to have a significant impact on mortality. 

Researchers from Ohio State University found teens with a mood disorder and a cannabis habit are 3.28 times more likely to self-harm and 59 per cent more at risk of dying from all causes.

The risk of death from an unintended overdose is 2.4 higher than in people who avoid the drug, and the likelihood of being a victim of murder is 3.24 times higher, the study finds. 

‘Marijuana use and addiction is common among youth and young adults with mood disorders, but the association of this behavior with self-harm, suicide and overall mortality risk is poorly understood in this already vulnerable population,’ says lead author Dr Cynthia Fontanella.

‘These findings should be considered as states contemplate legalizing medical and recreational marijuana, both of which are associated with increased cannabis use disorder.’

The study, published in JAMA Paediatrics, reviewed anonymous cases of more than 200,000 people aged between 10 and 24. 

Cannabis use was observed in 21,040 of the teens with mood disorders, one in ten of the study cohort. 

Cannabis abuse was more common in older people as well as in black people and males.  

Over the seven-year observation period, participants were closely studied as well to determine the prevalence of non-fatal self-harm, all-cause mortality, suicide, overdoses, car crashes, and homicides.

‘We also found that cannabis use disorder was significantly associated with self-harm, including death by unintentional overdose and homicide,’ Professor Fontanella said.

‘Unfortunately, while this observational study calls attention to these associations, it is unable to contribute to our understanding of causality or mechanism.’

The researchers say that not only are youths with mood disorders more likely to use cannabis, but the drug can also worsen symptoms and interfere with treatments. 

Decreasing the rates of cannabis use and cannabis use disorder might reduce risk,’ said senior author Professor Mary Fristad.

‘Individual and family-based therapy models, including cognitive behavioral therapy and motivational enhancement therapy have been shown to decrease cannabis use in youth.’

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