A new study led by the American Heart Association has recently investigated the relationship between cannabis use and brain health. Despite the perception that this drug is harmless, which led to its legalization in several states across the U.S., as well as in other countries such as the Netherlands, animal studies show that its psychoactive component, THC (tetrahydrocannabinol) could cause behavioral and cognitive abnormalities, particularly if exposure occurs prenatally or during adolescence.
While further research is necessary in order to clearly map the risks and benefits associated with cannabis, scientists warn that there might be an increased risk of cognitive impairment associated to the use of this substance.
Cannabis contains two main substances, THC and CBD (cannabidiol). While THC is the compound that gives the sensation of being high, CBD has anti-inflammatory and antioxidant properties that can have significant therapeutic benefits. This compound is similar to substances that the human body produces naturally (endocannabinoids), which are involved in the regulation of many fundamental bodily processes during life, including learning, memory, pain control, and sleep. The proper functioning of endocannabinoids is essential to prenatal brain development and brain maturation during adolescence.
According to scientists, since both THC and endocannabinoids attach to neurons through molecules called cannabinoid receptors, exposure to THC may interfere with and disrupt the normal actions of endocannabinoids, particularly during prenatal life and adolescence.
“Data obtained in these animal studies demonstrate that disruption of endocannabinoid pathways leads to behavioral and cognitive abnormalities, such as poorer memory and learning ability and a heightened sensitivity to stress. Also, there may be vital life periods – gestation and adolescence – when the brain may be particularly vulnerable to the impact of THC,” explained study lead author Fernando Testai, a professor of Neurology and Rehabilitation at the University of Illinois at Chicago.
Several studies performed on humans led to similar results: children whose mothers consumed cannabis during pregnancy had more psychological problems and poorer cognitive function, while cannabis use during adolescence has been associated with the thinning of the prefrontal cortex, a brain area crucial for cognition. Moreover, regular consumers tended to score poorly on verbal memory tests and driving tests. Finally, cannabis users were found to have an increased risk of clot-caused stroke, with one study finding a 17 percent and another a 24 percent increase in strokes among this population.
Further research is needed to clarify whether the relationship between cannabis use and brain health depends upon a person’s age, whether different types of cannabis impact the brain differently, or whether there are differences in brain health effects depending on whether the substance is smoked or consumed in edibles. Most importantly, urgent research is needed to clarify the ways in which cannabis interacts with prescription medications, particularly in elderly people who may be using multiple drugs such as blood thinners, antiarrhythmia or anticonvulsant medications to treat chronic health issues.
“Our understanding of the effects of marijuana on the brain is imperfect, and human research in this area is a work in progress. Still, the results of recent animal studies challenge the widely accepted idea that cannabinoids are harmless and call for caution when using marijuana, particularly while pregnant or during adolescence,” concluded Professor Testai.
The study is published in the journal Stroke.