Long-Term Effects of Marijuana Usage
Long-term marijuana use is associated with significant mental health and respiratory problems, including chronic bronchitis, COPD, cardiovascular risks, cognitive impairment, and potential development of cannabis use disorder. 1, 2
Mental Health Effects
- High doses of THC may be associated with psychosis in vulnerable individuals, with increasing potency of cannabis products (THC concentration nearly doubled from 9% in 2008 to 17% in 2017) elevating this risk 1, 2
- Cannabis use is associated with increased risk for developing depressive disorders and may exacerbate existing psychiatric disorders in vulnerable individuals 2, 3
- Early onset of cannabis use, especially weekly or daily use, strongly predicts future dependence and worse psychiatric outcomes 2, 3
- Long-term cannabis use can impair cognitive function, particularly affecting:
Physical Health Effects
Respiratory System
- Smoking cannabis affects lung function and is associated with pulmonary conditions including chronic bronchitis and chronic obstructive pulmonary disease 1, 2
- The link between cannabis smoking and lung cancer remains unclear, often confounded by concomitant tobacco use 1, 2
Cardiovascular System
- Long-term cannabis use is associated with adverse cardiovascular events, including:
Other Physical Effects
- Long-standing cannabis use can lead to cannabinoid hyperemesis syndrome, characterized by cyclical vomiting episodes that are relieved by hot showers 2, 3
- Cannabis use during pregnancy may negatively affect fetal brain development and increase risk for premature birth 1
Cannabis Use Disorder
- Approximately 10% of adults with chronic cannabis use may develop cannabis use disorder, characterized by clinically significant impairment or distress 2, 5
- Withdrawal symptoms typically occur within 3 days after cessation and may last up to 14 days, including:
Special Population Concerns
Adolescents and Young Adults
- Cannabis use may have a deleterious effect on adolescent brain development 1
- Neuroimaging studies have shown reduced hippocampal volume and density with long-term use, particularly when started at younger ages 4
- Early cannabis use is associated with neuropsychological and neurodevelopmental decline, elevated risk for psychotic disorders in adulthood, higher risk for depression, and suicidal ideation or behavior 1
Older Adults
- Cannabis use has increased among adults aged 65 years or older 1
- Older adults who use cannabis may be at higher risk for behavioral health issues, including anxiety and depression 1
- Cannabis-related emergency department visits among older adults have increased, with acute cannabis toxicity potentially associated with sedation, obtundation, and myocardial ischemia or infarction 1
Safety Concerns
- Cannabis users are at higher risk of motor vehicle accidents, with drivers testing positive for cannabis being more than twice as likely to be involved in crashes 3, 6
- The percentage of fatal motor vehicle accidents involving cannabis alone increased from 9.0% in 2000 to 21.5% in 2018 3
- Cannabis impairs driving ability by affecting reaction time and coordination 3, 7
Clinical Implications
- The increasing potency of cannabis products (with concentrates potentially reaching 70% THC) significantly elevates all health risks 1, 2
- Vaping cannabis poses unique risks, as demonstrated by the 2019 outbreak of acute lung injury associated with THC concentrate and vitamin E acetate 1
- Healthcare providers should be aware of the documented health effects of cannabis use to provide accurate information to patients 1, 2