Working memory capacity predicts cannabis-induced effects on alcohol urge

Area of Science:

• Neuroscience
• Psychology

Background:

• Cannabis's effect on alcohol urge varies, potentially due to individual differences.
• Working memory capacity (WMC) influences drug cue reactivity and alcohol use.
• Previous research shows mixed results on the cannabis-alcohol urge relationship.

Purpose of the Study:

• To investigate if WMC moderates the acute effects of cannabis on alcohol urge.
• To examine the relationship between different WMC measures and alcohol urge after cannabis use.

Main Methods:

• A randomized, placebo-controlled crossover trial involving 125 participants (21-44 years old) with heavy alcohol and frequent cannabis use.
• Participants smoked placebo, 3.1% THC, and 7.2% THC cannabis cigarettes across three lab sessions.
• Working memory capacity was assessed using n-back, operation span (OS), and symmetry span (SS) tasks prior to cannabis administration.

Main Results:

• Higher WMC, measured by SS, correlated with significantly lower alcohol urge after the 7.2% THC dose compared to placebo.
• No significant moderation of alcohol urge by WMC was found for the 3.1% THC dose or with the OS task.
• Lower WMC, indicated by n-back scores, was associated with higher overall alcohol urge, but did not moderate cannabis's effect.

Conclusions:

• Individuals with higher WMC experience reduced alcohol urge acutely following cannabis use, particularly with higher THC doses.
• The potential benefit of cannabis as an alcohol substitute may be limited for individuals with lower WMC.
• Findings highlight WMC as a crucial factor in understanding the nuanced relationship between cannabis use and alcohol urge.