Brain breakdown: Medical professionals worry about marijuana’s effect on young people

As the government moves toward legalizing marijuana, medical professionals hope tight regulations decrease use and protect youth.


Even as the federal Liberal government moves toward legalizing marijuana, medical professionals hope that tight regulations will decrease its use and protect young people from what studies have proven can be significant damage to their brains.

“Regular use of marijuana before the age of 25 has been shown to negatively affect brain development leading to lower IQ in adulthood,” says Dr. Raina Fumerton, the Northern Health Authority’s Terrace-based medical health officer for the northwest.

“Marijuana can actually worsen symptoms of depression and anxiety and can cause paranoia and hallucinations… It has also been shown to trigger early onset of schizophrenia in those who are vulnerable… Our recommendation is that people under the age of 25 should not be using cannabis (also known as marijuana),” she said, adding that she and most of her medical colleagues in the province agree.

Earlier this year the Canadian Centre on Substance Abuse (CCSA) released a major report summarizing the current research on marijuana with over 400 research references.

“Current debates about cannabis use are rife with mere opinion and misinformation. And, to complicate the matter further, the evidence related to the possible health risks of cannabis use appears to be contradictory. How do we weigh the evidence?” the report asks in its forward before doing exactly that.

The report highlights studies which have looked at brain MRI images as well as ones about the biological impact of marijuana on the brain and found that marijuana can actually alter the brain structure, damage the prefrontal cortex and destroy grey matter. Because of that damage to what researchers called “the thinking brain,” young people using marijuana will start to rely more on “the emotional brain” to control their behaviour, which “can lead to increased risk-taking behaviour, poor decision-making and inferior reasoning ability,” the study said.

The researchers go on to say that “current evidence suggests a strong relationship between cannabis (marijuana) use and psychosis,” but they call for more research into exactly how marijuana-use is connected with depression, anxiety, eating disorders and behavioural disorders.

Dr. Fumerton said that another health concern about marijuana is that it is addictive and can easily lead to dependence.

“About one in ten people who try marijuana will become addicted and dependent and will experience withdrawal symptoms when they stop,” she said. The CCSA study confirmed similar statistics, saying that 5-9 per cent of those who use marijuana will develop dependence.

“This rate increases to about 17 per cent for those who start using during adolescence,” the study said, adding that risk of dependence is also affected by other factors such as genetics. The researchers of the CCSA study expressed concern about the public perception of marijuana/cannabis as relatively harmless compared to other substances.

“Cannabis is not a harmless drug. It can be addictive and the risk increases the earlier it is used. Early and frequent use also increases the risk of short-term cognitive impairment and under performing in school, as well as psychotic symptoms and disorders… All Canadians need to be made more aware of the health risks and harms,” said the study.

Dr. Fumerton agrees, and says that the key with legalization will be tight regulations with the goal of decreasing access, something she calls a harm reduction approach. The other key is to make sure that regulations are evidence-based, not money driven, and the effects closely monitored to ensure that the regulations are actually decreasing harms and access — what she calls the public health framework.

“We need to be constantly researching and looking at the data and monitoring how this is impacting the health of people in the province and what the usage patterns are,” said Dr. Fumerton.

“We need to know where the policy is or is not working so that we can make changes along the way. There needs to be that flexibility built in… and starting off being more conservative and more tightly regulated is a better approach than being more liberal,” she said. “I and we in public health — physicians in B.C. — are very concerned about those harmful effects (of marijuana), but that said, the reality is that many people currently use marijuana products.”

A 2013 McCreary study found that in B.C., 26 per cent of youth Grades 7 to 12 had tried marijuana. In northwest B.C., that went up to 42 per cent, and over half of those (60 per cent) had used it in the past month.

With that in mind, Fumerton hopes that legalizing and tightly restricting where, how and to whom marijuana is sold will decrease access to this substance, especially among youth to whom it can be so harmful.