The calming but deteriorating effects of cannabis use
Today’s topic is a bit more on the serious side, it's about the use of cannabis and how it can impact brain health. With so much buzz around cannabis being legalized and used more widely, it’s easy to overlook some of the risks, especially when it comes to long-term effects on the brain. Don’t worry, though—we’re not here to lecture, just to share some useful insights that might surprise you! This blog will explore cannabis poses to brain health by drawing on insights from three major studies, and conclude with some actionable recommendations for minimizing harm.
Cannabis use has become more mainstream in recent years, driven by widespread legalization and its growing acceptance for both medical and recreational purposes. However, while cannabis may offer benefits in certain contexts, emerging research shows that regular or long-term use can have significant adverse effects on brain health. Studies reveal that cannabis can alter brain structure, function, and even blood flow to key regions, which can impair cognitive performance, memory, and emotional regulation.
The Long-Term Effects of Cannabis on Brain Structure
One of the most comprehensive studies on the effects of cannabis on brain structure was published in Neuropsychopharmacology. This research focused on the long-term impact of chronic cannabis use and found that regular use, particularly when started during adolescence, is linked to significant changes in the brain. The study highlighted reductions in the volume of the hippocampus and amygdala—two regions critical for memory regulation .
The hippocampus is responsible for memory formation, and the study showed that prolonged cannabis use can lead to a shrinking of this important brain region. This shrinkage impairs the ability to form new memories and may contribute to difficulties in learning or recalling information. The amygdala, which plays a crucial role in managing emotions and responses to stress, was also found to be smaller in chronic cannabis users, potentially leading to heightened emotional instability, anxiety, and depression.
Critically, the study noted that these structural changes might not be fully reversible even after stopping cannabis use, especially if use began during adolescence. Since the adolescent brain is still developing, exposure to cannabis during this sensitive period can have lasting effects on brain maturation.
Functional Changes: Impaired Cognition and Emotional Regulation
A more recent study, published in Current Addiction Reports, provides a deeper look into how cannabis affects both brain structure and function. The study consolidates evidence showing that chronic cannabis use disrupts functional connectivity, meaning it impairs how different parts of the brain communicate and work together .
Specifically, the prefrontal cortex—a brain region responsible for decision-making, impulse control, and working memory—shows reduced activity in frequent cannabis users. This is particularly concerning because the prefrontal cortex is essential for executive functions like problem-solving, planning, and making sound judgments. The reduction in connectivity between the prefrontal cortex and other brain areas can lead to poor decision-making, impaired focus, and an inability to control impulses effectively.
This disruption also extends to the brain's reward system, which governs motivation and pleasure. Cannabis users may develop blunted responses to natural rewards, such as social interactions or achievements, contributing to what is sometimes described as "amotivational syndrome." This condition is characterized by apathy, lack of motivation, and reduced interest in activities that would normally be engaging.
Effects on Brain Perfusion and Cognitive Function
Another important study, published in Neuropsychopharmacology in 2002, examined the effects of marijuana use on brain perfusion (blood flow) and cognitive function. Brain perfusion is critical because it ensures that the brain receives sufficient oxygen and nutrients to function optimally. The study found that chronic cannabis smokers experienced reduced blood flow to key areas of the brain, particularly the frontal lobes, which are vital for attention, decision-making, and cognitive flexibility .
The reduced perfusion was directly linked to impaired cognitive performance in areas such as attention span, working memory, and reaction times. Even more concerning, these deficits were observed not just immediately after cannabis use, but also in the long term, suggesting that the brain's ability to regulate blood flow may be permanently affected by chronic marijuana use. This reduction in brain perfusion can lead to slower cognitive processing, making it harder to focus, solve problems, or respond to new information quickly and accurately.
The Cumulative Risks for Brain Health
Taken together, these studies paint a clear picture of the risks cannabis poses to brain health, particularly with long-term or frequent use. Key risks include:
Memory Impairment: Structural changes in the hippocampus and reduced brain perfusion lead to difficulties in memory formation and recall.
Emotional Instability: Changes in the amygdala and impaired functional connectivity can cause emotional dysregulation, anxiety, and depression.
Cognitive Decline: Chronic use reduces activity in the prefrontal cortex, impairing decision-making, problem-solving, and impulse control.
Reduced Motivation: Blunted brain responses to rewards can lead to reduced interest in everyday activities and overall apathy.
Recommendations for Protecting Brain Health
While cannabis use may be widespread, there are steps you can take to minimize its potential harm, particularly for brain health. Here are some recommendations:
Limit Frequency of Use: Regular, heavy cannabis use is more strongly associated with brain changes and cognitive impairments. Reducing the frequency of use can help protect brain structure and function.
Don’t Use Until Adulthood: The adolescent brain is still developing, making it especially vulnerable to the effects of cannabis. Avoid using cannabis during teenage years to protect brain development.
Choose Lower-THC Products: THC (tetrahydrocannabinol), the main psychoactive compound in cannabis, is primarily responsible for its negative cognitive effects. Opting for lower-THC or higher-CBD strains may reduce the risk of brain-related side effects.
Take Regular Breaks from Use: Periodic breaks from cannabis can give your brain a chance to recover and may reduce the risk of developing dependence or tolerance.
Stay Informed and Educated: Research into the effects of cannabis on the brain is ongoing. Staying updated on the latest findings can help you make informed decisions about your use.
Conclusion
While cannabis may have therapeutic uses and is becoming more and more socially accepted, it's essential to recognize its potential dangers, particularly for brain health. As these studies show, long-term or frequent cannabis use can lead to significant changes in brain structure, impaired cognitive function, and emotional dysregulation. For adolescents and heavy users, these changes can be lasting and difficult to reverse.
By taking proactive steps to limit use, opting for THC products, and staying informed, you can reduce the potential harm cannabis poses to your brain. Remember, your mind is your most valuable asset, and protecting it should always be an priority.
References
Battistella, G., Fornari, E., Annoni, JM. et al. Long-Term Effects of Cannabis on Brain Structure.Neuropsychopharmacol 39, 2041–2048 (2014). https://doi.org/10.1038/npp.2014.6
Colyer-Patel, K., Romein, C., Kuhns, L. et al. Recent Evidence on the Relation Between Cannabis Use, Brain Structure, and Function: Highlights and Challenges. Curr Addict Rep 11, 371–383 (2024). https://doi.org/10.1007/s40429-024-00557-z
O'Leary, D., Block, R., Koeppel, J. et al. Effects of Smoking Marijuana on Brain Perfusion and Cognition.Neuropsychopharmacol 26, 802–816 (2002). https://doi.org/10.1016/S0893-133X(01)00425