Razi Berry

With changing thoughts and legislation surrounding the use of cannabis, the need to understand the effects of cannabis use on adolescent development is even more necessary. Most studies that have linked alcohol and cannabis misuse and abuse to cognitive impairment have not been designed to differentiate a causal relationship between use and long-term cognitive impairment.

It is generally understood that cognitive impairment plays a role in vulnerability to substance use in general. However, a recent study has also shown that there are lasting effects from cannabis use on important cognitive functions. These effects are more pronounced than those seen with teen alcohol abuse.

Effects more pronounced than those seen with teen alcohol abuse

“While many studies have reported group differences in cognitive performance between young users and non-users, what had yet to be established was the causal and lasting effects of teen substance use on cognitive development,” said co-author and PhD student at Université de Montréal, Jean-François G. Morin. Senior author and investigator Dr. Patricia Conrod, from the Department of Psychiatry at Université de Montréal, added that “very few studies are designed to look at this question from a developmental perspective. Our study is unique in that it followed a large sample of high school students from 7th to 10th grade using cognitive and substance-use measures. Using this big-data approach, we were able to model the complex nature of the relationship between these sets of variables.”

Research followed nearly 4,000 teens over a four-year period

The research followed nearly 4,000 teens over a four-year period. Assessment year-to-year of changes in substance use and cognitive development across an array of cognitive domains such as recall memory, perceptual reasoning, inhibition and working memory were looked at.

The study found that vulnerability to cannabis and alcohol use in adolescence was associated with generally lower performance on all cognitive domains.

Study found vulnerability to cannabis and alcohol use in adolescence associated with generally lower performance on all cognitive domains

“However, further increases in cannabis use, but not alcohol consumption, showed additional concurrent and lagged effects on cognitive functions, such as perceptual reasoning, memory recall, working memory and inhibitory control,” Conrod said. “Of particular concern was the finding that cannabis use was associated with lasting effects on a measure of inhibitory control, which is a risk factor for other addictive behaviours, and might explain why early onset cannabis use is a risk factor for other addictions.” Morin added: “Some of these effects are even more pronounced when consumption begins earlier in adolescence.”


Razi Berry is the founder and publisher of the journal Naturopathic Doctor News & Review  that has been in print since 2005 and the premier consumer-faced website of naturopathic medicine, NaturalPath.  She is the host of The Natural Cancer Prevention Summit and The Heart Revolution-Heal, Empower and Follow Your Heart, and the popular 10 week Sugar Free Summer program. From a near death experience as a young girl that healed her failing heart, to later overcoming infertility and Chronic Fatigue Syndrome and Fibromyalgia through naturopathic medicine, Razi has lived the mind/body healing paradigm. Her projects uniquely capture the tradition and philosophy of naturopathy: The healing power of nature, the vital life force in every living thing and the undeniable role that science and mind/body medicine have in creating health and overcoming dis-ease. Follow Razi on Facebook at Razi Berry and join us at  Love is Medicine  to explore the convergence of love and health.

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