Baycrest

In terms of therapeutic effects, a review published by the U.S. National Academy of Sciences found conclusive or substantial evidence that cannabis or cannabinoids are effective for the treatment of chronic pain, chemotherapy-induced nausea and vomiting, and patient-reported MS spasticity symptoms. The review found moderate evidence that cannabis improves short-term sleep outcomes for people with a number of conditions, and limited evidence that it can increase appetite and decrease weight loss for people with HIV/AIDS; reduce anxiety symptoms in individuals with social anxiety disorders; and symptoms of Tourette's syndrome. A trial is under way in Toronto to see if a synthetic cannabinoid will improve behaviours associated with dementia. But overall, Dr. Conn said there is "amazingly little research on marijuana use by people who are older." Dr. Conn is currently leading a Canadian Coalition for Seniors' Mental Health project funded by Health Canada that will result in national guidelines related to the use of cannabis, alcohol, opioids and benzodiazepines among older adults. Effects on young people: more study required The impact of cannabis on young people requires more study as well. In his own research, Dr. Paus has found that male teens who experimented with cannabis before age 16, and have a high genetic risk for schizophrenia, show a different trajectory of brain development than low risk peers (whether or not they used cannabis). His findings suggest the drug might interfere with the maturation of the cerebral cortex in these individuals. The next step is to look at the brain scans of about 1,000 young adults with an average age of 25 who were previously studied as teens. "Our study will inform the public about whether early cannabis use changes the trajectory of a person's brain health between their teens and young adulthood," he said. A study on Adverse Health Effects of Marijuana Use, published in the New England Journal of Medicine in June 2014, notes that around nine per cent of those who experiment with the drug will become addicted (according to criteria for dependence in the Diagnostic and Statistical Manual of Mental Disorders, 4th edition). Dr. Conn said most people can use a drug such as marijuana moderately and not get addicted, but he knows of older adults who are "quite addicted" and smoke marijuana every day. "It's a particular problem if they're travelling and can't take it across the border. If they don't have their joint they may have symptoms of withdrawal, and get moody and irritable." Legalization raises concerns about drug-impaired driving Meanwhile, both doctors are adamant that people who are under the influence should not get behind the wheel of a car. Dr. Paus said there's good evidence of an association between cannabis use and car crashes. A 2017 Public Safety Canada study on drug-impaired driving showed that among those who have used cannabis, 28 per cent said they have operated a vehicle while under the influence. "The level of alertness is decreased and you're not as capable of functioning, which is why there's so much concern about driving," Dr. Conn said. For more articles like this visit: baycrestfoundation.org/brainmatters BrainMatters SPRING/SUMMER 2018 9

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