Baycrest

CANNABIS: Effects on the body and brain A s Canada gets closer to the legalization of cannabis, we are learning details almost daily about the growers, provincial plans for retail and distribution, fluctuating stock prices and policing dilemmas. Scientists and physicians are watching closely, too, as events unfold and hoping that the public at large has a good understanding of the health effects. "When you smoke, what are you getting into your system? Chemically speaking, about 100 different chemicals are contained in marijuana, in the plant," says Dr. Tomáš Paus, senior scientist, and the Anne and Max Tanenbaum Professor and Chair in Population Neuroscience at the Rotman Research Institute at Baycrest. Dr. Paus notes that the two main active ingredients are: • Tetrahydrocannabinol (THC), which is psychotropic and affects the brain; it's known to be propsychotic, inducing anxiety and triggering acute symptoms of psychosis, delusions and hallucinations. • Cannabidiol (CBD), which is believed to be an anti-convulsant that can act against seizures and potentially as an anxiolytic, relieving anxiety. The Canadian Centre on Substance Abuse says "chronic cannabis use has been associated with mild impairments of memory, attention and other cognitive functions." Dr. Paus said that over the past decade or more in the black market, "the ratio of THC ('bad') to CBD ('good') – has been increasing. Sellers have been getting more of the psychotropic THC in the plant and less of the cannabidiol, so it has become more potent." Dr. David Conn, a psychiatrist and vice president of education at Baycrest, described an older patient who decided to try smoking marijuana for chronic pain but didn't go through regulated channels for obtaining medical cannabis. "It knocked him out completely," said Dr. Conn. "He had to go to Emergency after using it because the effect was so powerful." With the advent of legalization, uncertainty about potency is likely to be addressed. A recent government consultation paper proposed that regulations would set out labelling requirements, including THC / CBD content. It also proposed warnings related to risks associated with cannabis use during pregnancy, dangers of impaired driving and risks of combining it with other substances such as alcohol. Health Canada does not recommend using cannabis, saying that it can impair concentration, ability to think and make decisions, reaction time and coordination. It notes that studies supporting the safety and efficacy of cannabis for therapeutic purposes are limited. Dr. Tomáš Paus Dr. David Conn 8 BrainMatters SPRING/SUMMER 2018

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