A study of individuals who reported heavy alcohol and cannabis use found that individuals with average and high working memory tended to have significantly lower urges to drink after smoking cannabis containing 7.2% THC compared to a placebo. This effect was not seen when the THC concentration in cannabis was 3.1%. Decreased working memory capacity was associated with an overall stronger urge to drink alcohol. This study addictive behavior.
Alcohol use disorder is a medical condition characterized by problematic patterns of alcohol use that cause significant impairment and distress. This includes symptoms such as difficulty controlling drinking, strong cravings for alcohol, continued use despite negative effects, and tolerance or withdrawal.
Research shows that 47.5% of individuals age 12 and older in the United States report alcohol use in the past month, and 10.2% of those who report alcohol use in the past year meet criteria for alcohol use disorder. Many people who use alcohol heavily also tend to use cannabis.
Research has shown that co-consuming alcohol and delta-9 tetrahydrocannabinol (THC), the main psychoactive cannabinoid found in cannabis, potentiates the pleasurable effects of both substances. Due to this learned or pharmacological response, cannabis use can cause the urge to drink alcohol.
Study author Rachel L. Gunn and colleagues wanted to investigate how cannabis consumption is associated with alcohol urges and whether working memory capacity moderates this association. They analyzed data from clinical trial NCT02983773 (Principal Investigator: J. Metrik).
Study participants were 125 people between the ages of 21 and 44 who reported heavy alcohol consumption and cannabis use at least twice a week. Of these, 32 percent were women.
These people first completed a baseline session after one night of cannabis abstinence. During this session, they reported demographic data and recent substance use history and completed an assessment of their working memory capacity (using an N-back task and a complex span task, specifically Manipulative Span and Symmetrical Span). Working memory capacity is the amount of information that a person can actively hold and manipulate in their mind at one time when performing cognitive tasks such as reasoning, learning, and problem solving.
Next, they completed three experimental sessions. During these sessions, they smoked a placebo (a cannabis cigarette without THC), cannabis with 3.1% THC, and cannabis with 7.2% THC. The order of these sessions was balanced so that each of these treatments had an equal chance of being the first, second, or third session (to control for order effects).
Participants reported alcohol urges before and after smoking. Cannabis cigarettes were rolled up on both ends and administered in a steady-paced puffing procedure (i.e., participants were instructed to inhale the cannabis smoke in a controlled pattern).
Results showed that participants with average and higher working memory capacity, as measured by a symmetry span task, tended to have significantly lower alcohol urges after smoking 7.2% THC compared to placebo, but not after smoking 3.1% THC cannabis. Performance on the surgical duration task was not associated with alcohol urges. Decreased working memory performance, as measured by the N-back task, was associated with increased alcohol urges overall, but N-back scores did not moderate the effects of cannabis on alcohol urges.
The N-back task is a memory test in which people see or hear a series of items and are required to say when the current item matches the one shown a few steps earlier. The Operation Span task tests how well you can mentally multitask by asking you to memorize a list of letters while solving a simple math problem. The symmetry span task measures visual working memory by determining whether a visual pattern is symmetric while memorizing the location of shapes on a grid.
“Findings suggest that people with high but low working memory have lower alcohol urges under the acute influence of cannabis. Although cannabis is increasingly recognized as an alternative to alcohol, people with low working memory may be less likely to experience such benefits when trying to reduce their drinking**,” study authors conclude.
This study sheds light on the psychological effects of cannabis in heavy alcohol and cannabis users. However, it is important to note that working memory capacity was measured using three different types of tasks, and the results will vary depending on the type of task used. Working memory capacity can also fluctuate over time depending on a person’s condition. Finally, the study authors investigated the effects of cannabis on alcohol urges immediately after smoking cannabis. It remains unclear how long the detected effects will last.
The paper, “Working memory capacity predicts cannabis-induced effects on alcohol urges,” was authored by Rachel L. Gunn, Lindy K. Howe, Holly K. Boyle, and Jane Metrik.
