Cannabis, derived from the Cannabis sativa plant, has a long history of use and is gaining increasing recognition and changing perceptions across many regions. Its prevalence has notably increased in recent years, with an estimated 61.9 million people in the United States using it in 2022. This growing availability and use underscore the importance of understanding its potential effects on the human body and mind.
Impact on Brain and Mental Health
Cannabis use can significantly influence brain function, particularly areas involved in memory, learning, attention, and decision-making. These cognitive functions can be impaired, with effects potentially lasting for several days after use. Adolescents are especially susceptible to these effects because their brains are still undergoing significant development, a process that continues until around 25 years of age. Exposure to tetrahydrocannabinol (THC), the main psychoactive compound in cannabis, during this developmental period may hinder the brain’s ability to refine and prune synapses, which are the connections between neurons.
There is an association between cannabis use and an increased risk of developing psychotic disorders, such as schizophrenia, especially with earlier and more frequent use, and higher THC potency. A recent study indicated that adolescents who use cannabis are at an 11 times higher risk of developing psychotic disorders compared to non-users. This heightened risk is particularly pronounced during adolescence, indicating a vulnerable period for cannabis exposure. Beyond psychosis, cannabis use has been linked to increased rates of other mental health conditions, including anxiety and depression.
Physical Health Concerns
Smoking cannabis can lead to various respiratory issues, similar to those caused by tobacco smoke. This method of consumption can harm lung tissues, causing scarring and damage to small blood vessels. Conditions such as chronic bronchitis, dyspnea (shortness of breath), and chronic obstructive lung disease have been associated with smoked cannabis.
Cannabis use also impacts the cardiovascular system. Immediately after use, cannabis can cause an increase in heart rate and blood pressure. This acute effect can put strain on the circulatory system and, over time, potentially contribute to conditions like coronary artery disease, heart attacks, and heart failure. Tachycardia, or a rapid heart rate, is a common cardiovascular effect.
Understanding Dependence and Problematic Use
Cannabis dependence, formally recognized as Cannabis Use Disorder (CUD), involves continued cannabis use despite experiencing clinically significant impairment. This disorder is characterized by a set of eleven criteria, including using larger amounts than intended, repeated attempts to quit, and experiencing physical or psychological problems related to use. Approximately 9–20% of cannabis users, particularly daily users, may develop CUD.
Factors contributing to the development of CUD include early initiation of use, frequent use, and the use of high-potency THC products. When individuals with CUD attempt to reduce or stop their cannabis use, they may experience withdrawal symptoms. These symptoms can include irritability, anxiety, insomnia, depressed mood, restlessness, and a decreased appetite. While these symptoms are generally not life-threatening, they can be uncomfortable and typically begin within 24 to 72 hours of cessation.
Impaired Functioning and Safety Risks
Cannabis use can acutely impair cognitive and motor functions, leading to significant safety risks. It can slow reaction time, impair coordination, and distort perception. These immediate effects can compromise a person’s ability to perform tasks requiring full cognitive and motor control, such as driving. Studies indicate that drivers with THC in their blood are approximately twice as likely to cause a fatal crash compared to those without drugs or alcohol in their system.
Even low doses of THC can impair cognitive and psychomotor skills necessary for safe driving, including decreased car handling performance, impaired time and distance estimations, and increased reaction times. These impairments can persist for several hours after consumption, with some effects lasting up to five and a half hours, even when users may feel ready to drive. Combining cannabis with other substances, such as alcohol, can further intensify these impairments, increasing the risk of accidents and poor decision-making.