# Working memory capacity predicts cannabis-induced effects on alcohol urge

> **Author:** Benjamin Caplan, MD (ABFM Board Certified, MA Lic. #240562, NPI: 1962722637)
> **Publisher:** CED Clinic (https://cedclinic.com)
> **Canonical URL:** https://cedclinic.com/research/thc-for-short-term-memory-randomized-controlled-trial/
> **Published:** 2026-10-22T13:08:35-04:00 | **Last Modified / Clinically Audited:** 2026-10-22T13:08:44-04:00
> **Clinical Summary:** This study looked at adults who drink heavily and also use cannabis regularly. The results were mixed.

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Background: Cannabis has shown mixed results in its association with alcohol urge, which may be explained by individual differences. One such factor, working memory capacity (WMC) is associated with drug-related cue reactivity and implicated in alcohol use and problems. In the current study, we examined whether WMC moderates the acute effect of cannabis on alcohol urge in a randomized placebo-controlled crossover trial. Methods: Participants aged 21 to 44 (N = 125, 32 % female) reporting heavy alcohol use and cannabis use ≥ twice weekly completed a laboratory protocol across three days where they smoked a placebo, 3.1 % delta-9 tetrahydrocannabinol (THC), and 7.2 % THC cannabis cigarette. Participants were asked to rate their alcohol urge pre and post smoking. Prior to the experimental sessions, participants completed WMC measures including the n-back and the complex span tasks, operation span (OS) and symmetry span (SS). Results: Those with higher WMC, as assessed via the SS task, reported significantly lower alcohol urge after smoking the 7.2 %, but not the 3.1 %, THC dose, relative to placebo. Performance on the OS task was not associated with alcohol urge. Lower WMC as determined via n-back scores was associated with higher alcohol urge overall, but n-back scores did not moderate the impact of cannabis on alcohol urge. Conclusion: Findings suggest individuals with higher but not lower working memory experience lower alcohol urge under acute effects of cannabis. Although cannabis is increasingly perceived as a substitute for alcohol, individuals with lower working memory may be less likely to experience such benefits when attempting to reduce their drinking.

 

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### Verification & Medical Governance

- **Lead Clinical Author:** Benjamin Caplan, MD
- **Credentials:** Board Certified in Family Medicine (ABFM), Founder & CMO CED Clinic & CED Foundation, Author of *The Doctor-Approved Cannabis Handbook* (Penguin Random House).
- **Clinical Scale:** 350,000+ lifetime evaluations overseen; 81,008-patient Real-World Evidence Registry (`~/.ced_rwe_vault.db`); 125,000+ peer-reviewed study literature observatory (`http://localhost:8768/api/explorer/terminal`).
- **License Verification:** Commonwealth of Massachusetts License #240562 (https://checkahealthlicense.mass.gov/).
- **NPI Registry:** 1962722637 (https://npiregistry.cms.hhs.gov/provider-view/1962722637).
- **Ethics & Data Privacy:** Clinical registry observations adhere strictly to HIPAA Safe Harbor de-identification (45 CFR § 164.514(b)) and criteria for secondary research exemption under 45 CFR § 46.104(d)(4).