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History of Cannabis Dependence Associated With Problematic Mental Health

April 28, 2020

Adults with a history of cannabis dependence had dramatically lower rates of positive mental health, and were less likely to have lived without psychiatric disorders or addictions in the past year, compared with adults without a history of cannabis dependence, according to a study of Canadians published in Advances in Preventive Medicine.

“Our findings illustrate that for many adults, a history of cannabis dependence casts a very long shadow, with a wide range of associated negative mental health outcomes,” said lead author Esme Fuller-Thomson, PhD, professor at the University of Toronto in Canada.

The study compared 336 adults with a history of cannabis dependence to 20,441 adults without a history of cannabis dependence. Data stemmed from Statistics Canada's 2012 Canadian Community Health Survey-Mental Health.

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According to the study, 28% of participants with a history of cannabis dependence were still cannabis dependent. In addition, 47% of those with a history of cannabis dependence had some form of mental illness or substance dependence in the past year. Meanwhile, 43% reported excellent mental health.

In comparison, 8% of adults without a history of cannabis dependence had some form of mental illness or substance dependence in the past year, while 74% reported excellent mental health.

Study requirements for excellent mental health were almost daily happiness or life satisfaction in the past month, high levels of social and psychological well-being in the past month, and no psychiatric disorders or addictions in the past year.

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“It is important to note that adults without a history of cannabis dependence had more than 9 times the odds of absence of psychiatric disorders or addictions in the past year and more than 3 times of the odds of positive mental health in comparison to those with a history of cannabis dependence,” researchers wrote. “These results suggest a strong association between history of cannabis dependence and problematic mental health outcomes.” 

Women, older adults, those with higher levels of social support, and those who had never had major depressive disorder or generalized anxiety disorder were more likely to report positive outcomes, according to the study. 

“It is important to remember that the legalization of cannabis is not solely about a profitable new business," Dr. Fuller-Thomson said. “With more users and subsequently more people who are cannabis dependent, there will be very serious long-term mental health repercussions that individuals, families, and the health care systems must address.”

—Jolynn Tumolo

References

Fuller-Thomson E, Jayanthikumar J, Redmond ML, Agbeyaka S. Is recovery from cannabis dependence possible? Factors that help or hinder recovery in a national sample of Canadians with a history of cannabis dependence. Advances in Preventive Medicine. 2020;618398. 

A history of cannabis dependence associated with many negative mental health outcomes [press release]. Toronto, Canada: University of Toronto; April 22, 2020.

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