Marijuana use has become increasingly prevalent across various age groups in recent years, with significant increases noted particularly among adolescents and older adults. The relationship between cannabis and mental health presents a complex picture, with documented effects ranging from potential short-term benefits to significant long-term risks. Research indicates that the impact of marijuana on mental health varies based on factors such as age of first use, frequency of use, individual vulnerability, and the specific mental health conditions present. This article examines the evidence surrounding how cannabis affects mental health, highlighting both potential benefits and documented risks.
The Dual Nature of Cannabis Effects on Mental Health
Cannabis interacts with the brain's endocannabinoid system, producing effects that can be both beneficial and detrimental to mental health. When THC binds to receptors in the brain, it produces the "high" feeling users seek, but also affects thinking, judgment, and emotional regulation. This interference can be double-edged. For some, marijuana may temporarily reduce feelings of stress or depression, offering short-term relief. For others, especially with frequent or heavy use, it can exacerbate or trigger mental health issues.
Some users report that marijuana helps them "expand consciousness," leading to an enhanced appreciation of simple pleasures in life such as listening to music, enjoying good food, and being out in nature. This effect has contributed to increased marijuana use in the over-65 population, which has risen by 75 percent in just the last three years. Many of these older individuals had used pot in the 1960s or 70s and are now seeking help with chronic medical conditions and the anxiety that comes with aging.
However, the negative effects are significant, particularly for adolescents and young adults. Research from New Zealand concluded that those who begin using marijuana regularly in their early teens may experience long-term memory impairment, lowered IQ, poor job and academic performance, and a greater risk of depression later in adulthood. Individuals from traumatic backgrounds are at higher risk of developing this pattern and are four to seven times more likely to become dependent on alcohol, marijuana, and other drugs.
Cognitive Effects and Brain Development
Studies indicate that early marijuana use can interrupt the normal development of gray matter, a type of brain tissue that helps control mental functions, thereby increasing schizophrenia risks. Early exposure to marijuana is also linked to changes in areas of the brain that are often connected with psychosis. Using marijuana heavily, especially during teenage years, may leave more permanent effects. Imaging tests have found that some adolescents who used marijuana had fewer connections in parts of the brain linked to alertness, learning, and memory.
Research also shows that tests reveal lower IQ scores in some people who use marijuana heavily during adolescence. The developing brain, which continues actively developing until the late 20s, appears particularly vulnerable to the effects of cannabis. Since 2019, rates of marijuana use have increased dramatically in adolescents, as have rates of emergency room visits in which marijuana is involved. This increase may be attributed to the decreased perceived risk of marijuana use, coupled with the rise in vaping methods and the stress of the COVID pandemic.
Long-term lung effects represent another concern, as marijuana smoke can inflame and irritate the lungs, potentially leading to increased bronchitis and other chronic lung conditions similar to those associated with tobacco smoking.
Cannabis and Psychosis/Schizophrenia
In high doses, weed can cause psychosis, which makes individuals paranoid or causes them to lose track of what's real and what's not. Those experiencing psychosis might hear or see things that aren't there and can have long-lasting odd thoughts. Psychosis typically lessens as the high subsides, unlike schizophrenia, which is a long-term condition affecting speech, focus, emotional expression, and reality perception.
Recent research suggests that if individuals start using marijuana at a young age, use it frequently, and for a long period, they could be at risk of developing schizophrenia or other mental conditions that involve psychosis. This risk appears higher in young men or people assigned male at birth, especially between 16 and 25 years of age. Studies also note that people at risk of a mental condition may be more likely to smoke marijuana at an earlier age, possibly as a way to medicate themselves.
Importantly, once schizophrenia develops, stopping marijuana use won't make the condition or its symptoms go away. The higher potency of THC in marijuana today compared to the 1960s has increased the risk of triggering psychosis, even in those without a genetic predisposition to schizophrenia.
Cannabis and Mood Disorders
Research shows mixed findings regarding the relationship between cannabis use and depression or depressive symptoms. One analysis found that cannabis use was associated with a small increase in risk for depressive outcomes. The analysis revealed a dose-response relationship, with a slightly higher observed risk in studies comparing heavy cannabis use to non-cannabis users. However, several primary research studies found positive associations, though confounding factors of polydrug use or unspecified cannabis use made it difficult for researchers to draw firm conclusions on the overall findings.
Some studies suggest that in some cases, cannabis has been shown to increase feelings of anxiety, paranoia, and panic attacks, especially with high-THC strains. It may also worsen symptoms in individuals with preexisting mental health conditions, such as depression, bipolar disorder, and schizophrenia.
While a 2018 study suggested slight relief from anxiety and depression symptoms after cannabis use, the effects were only felt in the short term. Long-term data suggested that cannabis use may have made symptoms worse. Similarly, while there has been emerging evidence suggesting that CBD could work as an antidepressant, the use of marijuana or THC products for depression presents different concerns. For example, synthetic weed has been linked to cases of increased suicidal thoughts, violent behavior, and psychosis. A 2023 survey found that cannabis use was associated with major depressive disorder and suicidal ideation in young adolescents.
Addiction and Dependency Issues
Many people believe marijuana is not addictive, but this is a misconception. If individuals think they're addicted to marijuana, getting an early diagnosis can help with treatment and prevent the risk of chronic conditions like schizophrenia. Addiction potential varies among individuals, with those from traumatic backgrounds being particularly vulnerable.
The relationship between marijuana use and other substance use disorders is significant. Individuals with traumatic backgrounds are four to seven times more likely to become dependent on alcohol, marijuana, and other drugs. This pattern suggests that marijuana use may be part of broader self-medication strategies for individuals dealing with unresolved trauma or mental health challenges.
Research Limitations and Clinical Considerations
Studies on cannabis use and mental health vary in their approaches to adjust for confounding factors, ranging from none to adjustment for more than 20 variables. Only half of the studies accounted for other types of substance use and/or mental health issues as potential confounders, which complicates the interpretation of findings.
The documented harmful health effects of smoking marijuana, such as increased bronchitis and other chronic lung conditions, should be considered when evaluating the overall impact of cannabis use on mental health. Additionally, marijuana use can cause increased impulsiveness, impaired driving ability, heightened anxiety, paranoia, and apathy, all of which can affect mental health and daily functioning.
As psychiatrists and mental health professionals continue to work with patients using medical marijuana, more research is needed to address the complex issues involved. The increasing availability of marijuana through dispensaries raises questions about potential impacts on adolescent and young adult use rates and subsequent effects on mental health, academic performance, and motor vehicle accidents.
Conclusion
The relationship between cannabis use and mental health presents a complex picture with both potential benefits and documented risks. While some individuals report temporary relief from anxiety or stress, research increasingly shows that heavy or chronic use can contribute to or worsen mental health conditions, particularly when initiated during adolescence. The evidence suggests that early and frequent marijuana use may increase the risk of psychosis, cognitive impairment, and mood disorders, especially in vulnerable populations.
Mental health professionals must weigh both sides of the equation when discussing cannabis use with patients. The individual's age, history of trauma, genetic predisposition to mental illness, and frequency of use all factor into the risk-benefit analysis. As the legal landscape continues to evolve and marijuana potency increases, ongoing research will be essential to develop more precise guidelines for safe use and to better understand the long-term effects on mental health.
Individuals considering cannabis use for mental health concerns should be informed about both the potential short-term benefits and the documented risks, particularly regarding brain development, addiction potential, and exacerbation of existing mental health conditions. A balanced, evidence-based approach to cannabis use is essential for protecting mental health across the lifespan.