Effects of cannabidiol on risky decision-making and autonomic function in alcohol use disorder.

McGuire E.; Hurzeler T.; Logge W.; Watt J.; McGregor I.; Suraev A.; Haber P.; Morley K. · Alcohol and alcoholism (Oxford, Oxfordshire) · 2026

**Background & Methods** This double-blind, placebo-controlled crossover trial enrolled 18 participants with alcohol use disorder (AUD) to evaluate cannabidiol (CBD) effects on autonomic function and risky decision-making. Participants completed the Columbia Card Task (CCT) following CBD and placebo administration, with simultaneous measurement of skin conductance responses (SCR) and high-frequency heart rate variability (HF-HRV) as autonomic indices. **Key Findings** • CBD significantly increased high-frequency heart rate variability (HF-HRV) compared to placebo (β = 0.53, SE = 0.19, P = .005; pBH = 0.020), suggesting enhanced parasympathetic autonomic tone during task performance. • CBD did not significantly affect skin conductance responses (P = .16, pBH = .326) or risky decision-making on the CCT (P > .63, pBH = 0.67), indicating no impact on sympathetic arousal or behavioral risk-taking patterns. • No significant interactions were found between drug condition and autonomic measures in predicting risky decision-making (drug × HF-HRV: P = .92; drug × SCR: P = .958; both pBH = .958), suggesting CBD's autonomic effects were independent of changes in risk behavior. **Dosage & Administration** Not reported. **Safety & Adverse Effects** Not reported. **Evidence Quality** This study has notable limitations that restrict generalizability. The modest sample size (n=18) substantially reduces statistical power to detect moderate-to-large effects. The study population was relatively healthy and non-treatment-seeking, which may not represent individuals with more severe AUD or those actively seeking intervention. The crossover design is methodologically sound but provides only short-term acute effects data without information on chronic CBD administration. The lack of dose specification and administration route details limits reproducibility. While the significant HF-HRV finding survives multiple comparisons correction (pBH), the functional significance remains unclear—increased parasympathetic tone during risky decision-making tasks does not necessarily translate to clinically meaningful behavioral improvement. The absence of adverse effect reporting is notable but may reflect incomplete safety monitoring rather than genuine absence of side effects. Overall, this represents preliminary evidence (Level II) that CBD may modulate cardiac autonomic function in AUD populations, though broader physiological and behavioral effects remain undetected. Further research with larger, more clinically representative samples and specified dosing protocols is warranted before clinical recommendations can be made.

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