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 .
Balanced placebo design with marijuana: Pharmacological and expectancy effects on impulsivity and risk taking
Rationale Marijuana is believed to increase impulsivity and risk taking , but the processes whereby it affects such behaviors are not understood . Indeed , either the pharmacologic effect of delta-9-tetrahydrocannabinol ( THC ) or the expectancy of receiving it may lead to deficits in cognitive processing and increases in risk taking . Objectives and methods We examined the relative effects of expecting to receive active marijuana and the pharmacological drug effects using a balanced placebo design . Young adult regular marijuana users ( N = 136 ) were r and omly assigned into one of four groups in a two × two instructional set ( Told THC vs. Told no THC ) by drug administration ( smoked marijuana with 2.8 % THC vs. placebo ) design . Dependent measures included subjective intoxication , behavioral impulsivity , and decision-making related to risky behaviors . Results Active THC , regardless of expectancy , impaired inhibition on the Stop Signal and Stroop Color-Word tasks . Expectancy of having smoked THC , regardless of active drug , decreased impulsive decision-making on a delay discounting task among participants reporting no deception and increased perception of sexual risk among women , consistent with a compensatory effect . Expectancy of smoking THC in combination with active THC  increased negative perceptions from risky alcohol use . Active drug and expectancy independently increased subjective intoxication . Conclusions Results highlight the importance of marijuana expectancy effects as users believing they are smoking marijuana may compensate for expected intoxication effects when engaged in deliberate decision-making by making less impulsive and risky decisions . Effects of marijuana on impulsive disinhibition , by contrast , reflect direct pharmacologic effects for which participants did not compensate
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 .