Long-Term Effects of Chronic Marijuana Use
Chronic marijuana use can lead to significant adverse health consequences including cannabis use disorder, psychiatric disorders, respiratory conditions, cardiovascular problems, cognitive impairment, and cannabinoid hyperemesis syndrome. 1
Mental Health Effects
- High doses of THC are associated with psychosis in vulnerable individuals, with risk increasing as cannabis potency increases 1
- Chronic cannabis use carries psychiatric risks that correlate with cumulative exposure and age of first use 1
- Cannabis use is associated with increased risk for developing depressive disorders and may exacerbate existing psychiatric conditions 1
- Regular and prolonged use can lead to mood disorders, anxiety, and suicidal ideations/tendencies 2, 3
- Early cannabis use is strongly linked to neuropsychological decline and elevated risk for psychotic disorders in adulthood 1
Cannabis Use Disorder
- Approximately 10% of adults with chronic cannabis use develop cannabis use disorder, characterized by clinically significant impairment or distress 1
- Early onset of cannabis use, especially weekly or daily use, strongly predicts future dependence 1
- Long-term daily users may experience withdrawal symptoms after cessation, including sleep disturbances, appetite changes, and abdominal pain that typically last up to 14 days 1
Respiratory Effects
- Cannabis smoking affects lung function and is associated with chronic bronchitis and chronic obstructive pulmonary disease 1
- Inhalation of marijuana smoke delivers 50% to 70% more carcinogens than tobacco smoke 4
- Chronic use is linked to reduced lung density, lung cysts, and chronic bronchitis 5
- The relationship between cannabis smoking and lung cancer remains unclear, often confounded by concomitant tobacco use 1
Cardiovascular Effects
- Long-term cannabis use is associated with adverse cardiovascular events including arrhythmias, myocardial infarction, and stroke 1
- Marijuana affects heart rhythm through multiple mechanisms, including blocking reuptake of catecholamines, causing sympathetic stimulation, and promoting a prothrombotic state 1
- Cannabis use can lead to dose-dependent increases in heart rate and blood pressure 5
Cognitive Effects
- Chronic cannabis use is associated with neurocognitive impairments that may persist for up to a month after last use 2, 4
- Cannabis use may have a particularly deleterious effect on adolescent brain development 1
- Regular use of high-THC products can impair learning, cognitive performance, and reduce educational attainment 6
Other Physical Effects
- Long-standing cannabis use can lead to cannabinoid hyperemesis syndrome, characterized by cyclical emetic episodes that are relieved by hot showers 1
- Cannabis use during pregnancy may negatively affect fetal brain development and increase risk for premature birth 1
- There is evidence of bone toxicity associated with chronic cannabis use 5
High-Risk Populations
- Adolescents and young adults are particularly vulnerable to the adverse effects of cannabis 1, 6
- Older adults who use cannabis may be at higher risk for behavioral health issues, including anxiety and depression 1
- Combined use of marijuana with tobacco results in greater increases in heart rate and vasoconstriction than either substance alone 1
- Individuals with pre-existing psychiatric disorders experience more severe negative effects from cannabinoids 3
Important Considerations
- Cannabis potency has increased dramatically over time, with average THC concentration almost doubling from 9% in 2008 to 17% in 2017, potentially elevating all health risks 1
- Cannabis concentrates may have THC levels as high as 70%, which could intensify adverse health effects 1
- Vaping cannabis poses unique risks, as demonstrated by the 2019 outbreak of acute lung injury associated with THC concentrate 1