Cannabis acutely impairs attention, concentration, episodic memory, associative learning, and motor coordination in a dose-dependent manner. Long-term cannabis use is associated with impairment of verbal memory and cognitive processing speed, which resolves after at least a month of abstinence. (See 'Neuropsychological effects' above.)
●Substantial evidence suggests that chronic cannabis use, especially during adolescence, is associated with later development of schizophrenia. The mechanisms responsible for the association between cannabis use and schizophrenia remain unclear. Some experts believe that early cannabis use is a causal factor in developing schizophrenia. (See 'Psychotic disorders' above.)
●Chronic cannabis use has not been found to be associated with serious or chronic medical conditions or death from medical conditions. Cannabis use is associated with injury and death from motor vehicle accidents. (See 'Adverse effects of cannabis use' above.)
●Cannabis smoking is associated with acute, transient respiratory symptoms, but chronic use is not associated with impaired lung function. (See 'Pulmonary' above.)
●Cannabis smoking acutely increases sympathetic activity and myocardial oxygen demand, and is associated with a small increased risk of myocardial infarction and stroke. (See 'Cardiovascular' above.)
●Cannabis use is also associated with periodontal disease, hyperemesis syndrome, and a lower sperm count. Hyperemesis syndrome is a relatively rare condition involving episodic severe nausea and vomiting and abdominal pain. Frequent cannabis smoking has been associated with a lower sperm count; the clinical significance of this finding is unknown. (See 'Dental' above and 'Hyperemesis syndrome' above and 'Reproductive' above.)