Experimental and observational evidence on substance use and metacognition among adults: a systematic review

Metacognition - the capacity to monitor, interpret, and regulate cognitive processes - is essential for adaptive behavioral regulation. Evidence on how substance use relates to metacognitive functioning remains heterogeneous across substances and study designs. This systematic review synthesized evidence examining the relationship between substance use and metacognition among adults.

Following PRISMA 2020 guidelines, we searched PubMed, PsycINFO, CINAHL, and Web of Science from inception through March 2026. Eligible studies included experimental and observational designs enrolling adults (≥18 years) and reporting metacognitive outcomes. Studies not assessing metacognition, involving non-adult samples, or non-empirical publications were excluded. Risk of bias was assessed using Joanna Briggs Institute appraisal tools. Findings were synthesized narratively.

Thirty-six studies (N = 2,852 participants) were included: randomized controlled trials (n = 16), quasi-experimental (n = 3), cross-sectional (n = 7), and case-control studies (n = 10). Experimental evidence showed substance-specific effects: alcohol findings were mixed across paradigms; cannabinoids generally impaired metacognitive accuracy and calibration; benzodiazepines impaired metacognitive awareness of performance and error detection; methamphetamine demonstrated dose-dependent effects on agency judgments; and nicotine replacement did not restore accuracy following abstinence. Craving states (nicotine, caffeine, methamphetamine) were associated with poorer monitoring and calibration. Observational studies indicated that cocaine, nicotine, opioid, cannabis, alcohol, and polysubstance use were generally associated with poorer metacognitive functioning, including greater maladaptive metacognitive beliefs and reduced monitoring accuracy, though some clinical comparisons showed domain-specific or relatively preserved functioning.

Experimental studies suggest acute substance-related alterations in metacognitive functioning, while observational studies indicate that substance use is generally associated with poorer metacognitive functioning. Greater standardization and longitudinal research are needed to clarify mechanisms and inform interventions.