RESULTS Although causality is unclear , heavy and dependent cannabis use is consistently associated with a high prevalence of comorbid psychiatric disorders and learning and memory impairments that seem to recover after a period of abstinence .
Evidence regarding other cognitive domains and neurological consequences including cerebrovascular events is limited and inconsistent .
Abstinence after treatment is only achieved in a minority of cases ; treatment targeted at reduction in use appears have some success .
Potential moderators of the impact of CUD on the brain include age of onset , heaviness of use , CUD severity , the ratio of ∆9-tetrahydrocannabinol to cannabidiol , and severity of comorbid disorders .
Current evidence of long-term effects of daily cannabis use and cannabis use disorder on brain-related outcomes is suggestive rather than conclusive but use is associated with psychiatric morbidity and with cognitive impairments that recover after a period of abstinence
AIMS To summarize and evaluate our knowledge of the relationship between heavy cannabis use , Cannabis Use Disorder ( CUD ) , and the brain .
The association between cannabis use and mood disorders: A longitudinal study.
BACKGROUND The association between cannabis use and mood disorders is well documented , yet evidence regarding causality is conflicting . This study explored the association between  cannabis use , major depressive disorder ( MDD ) and bipolar disorder ( BPD )  in a 3-year prospect i ve study . METHODS Data was drawn from waves 1 and 2 of the National Epidemiologic Survey on Alcohol and Related Conditions ( NESARC ) . MDD and BPD were controlled at baseline and defined as meeting full criteria in the 12 months prior to the follow-up . Initiation of cannabis use was defined as any cannabis used by former lifetime abstainers in the time period between baseline and follow-up . RESULTS Cannabis use was not significantly associated with increased incidence of MDD ( Adjusted Odds Ratio ( AOR ) for daily use=0.58(0.22 - 1.51 ) ) . Weekly to almost daily cannabis use was associated with increased incidence of BPD ( ( AOR for weekly to daily use=2.47(1.03 - 5.92 ) ) ; daily use was not ( AOR=0.52(0.17 - 1.55 ) ) . Baseline MDD was associated with initiation of cannabis use ( AOR=1.72(1.1 - 2.69 ) ) . A crude association between baseline BPD and incidence of cannabis use was not maintained in adjusted models ( AOR=0.61(0.36 - 1.04 ) ) . LIMITATIONS Lack of information regarding frequency of cannabis use at follow-up and limitations regarding generalization of the results . CONCLUSIONS Our findings do not support a longitudinal association between cannabis use and incidence of MDD . Results regarding the association between cannabis use and incidence of BPD are conflicting and require further investigation . Baseline MDD , but not BPD , may be associated with future initiation of cannabis use . This may have implication s for clinical , social and legislative aspects of cannabis use
RESULTS Although causality is unclear , heavy and dependent cannabis use is consistently associated with a high prevalence of comorbid psychiatric disorders and learning and memory impairments that seem to recover after a period of abstinence .
Evidence regarding other cognitive domains and neurological consequences including cerebrovascular events is limited and inconsistent .
Abstinence after treatment is only achieved in a minority of cases ; treatment targeted at reduction in use appears have some success .
Potential moderators of the impact of CUD on the brain include age of onset , heaviness of use , CUD severity , the ratio of ∆9-tetrahydrocannabinol to cannabidiol , and severity of comorbid disorders .
Current evidence of long-term effects of daily cannabis use and cannabis use disorder on brain-related outcomes is suggestive rather than conclusive but use is associated with psychiatric morbidity and with cognitive impairments that recover after a period of abstinence
AIMS To summarize and evaluate our knowledge of the relationship between heavy cannabis use , Cannabis Use Disorder ( CUD ) , and the brain .