Does Cannabis Cause Lasting Brain Impairments? A Review of Studies

The effects of long-term cannabis use on the developing brain have been a contentious issue. While some sources claim that the mind-altering effects are only short-term, others claim that the long-term effects are unknown and can be permanent and irreversible.

A group of researchers from the University of Montreal has analyzed previous research to determine the impact of cannabis on the developing brain. What they discovered was a tad surprising; cannabis creates a lasting impression in the hippocampus (controls memory and learning).

The compound in cannabis that causes the “high feeling” is known as THC. This is the same compound that is associated with alterations in brain function causing short-term memory loss, impaired learning, and loss of coordination and orientation. These effects usually last for about 6-8 hours, depending on the type of product that was consumed, potency, frequency of use, and body weight. From this recent analysis, it appears that these effects could linger for extended durations.

“When you consume cannabis you’re really flooding the system with the psychoactive plant chemical THC (tetrahydrocannabinol), which in the short term is really great at hijacking the brain’s reward system,” says Dr. Sharon Levy, an associate professor of pediatrics at Harvard Medical School.

When used over time cannabis may cause residual effects in the young brain. Some studies showed that cannabis users have poorer outcomes in academic and job performance as compared to non-users, especially when the habit was picked in their teen years.

However, the researchers also acknowledged that it is not possible to draw a direct correlation since those destined to have poorer outcomes may have a greater predisposition to try out cannabis. This, according to Dr. Igor Grant, is a chicken-and-egg scenario. In addition, it is not ethical to conduct randomized trials where you offer cannabis to some children and withhold it from some. Even with researchers holding different views on this issue, it is important to exercise caution as far as cannabis use in children is concerned.