The relationship between cannabis use by young people and psychosocial harm is likely to be multifaceted, which may explain the inconsistencies among studies. For example, some studies suggest that long-term deficits may be reversible and remain subtle rather than disabling once a person abstains from use.30 Other studies show that long-term, heavy use of marijuana results in impairments in memory and attention that persist and worsen with increasing years of regular use31 and with the initiation of use during adolescence.32 As noted above, early marijuana use is associated with impaired school performance and an increased risk of dropping out of school,27,29 although reports of shared environmental factors that influence the risks of using cannabis at a young age and dropping out of school33 suggest that the relationship may be more complex. Heavy marijuana use has been linked to lower income, greater need for socioeconomic assistance, unemployment, criminal behavior, and lower satisfaction with life.2,34
