Observational studyAddiction (Abingdon, England)2021
Familial factors may not explain the effect of moderate-to-heavy cannabis use on cognitive functioning in adolescents: a sibling-comparison study.
Observational study in Addiction (Abingdon, England), 2021. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 7 papers, 2 of them syntheses that pooled it.
What it found
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
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Who cites it
7 citing papers in PubMed, 2 syntheses or guidelines pooled it, 30 citations in OpenAlex.
- Unhealthy behaviors associated with mental health disorders: a systematic comparative review of diet quality, sedentary behavior, and cannabis and tobacco use.Frontiers in public health · 2023Pooled it
- Intelligence quotient decline following frequent or dependent cannabis use in youth: a systematic review and meta-analysis of longitudinal studies.Psychological medicine · 2021Pooled it
- Adaptive Treatment for Youth With Substance Use and Depression: Early Depression Response and Short-term Outcomes.Journal of the American Academy of Child and Adolescent Psychiatry · 2022Trial
- Associations between cannabis use frequency and suicidal thoughts and behaviors: A clinical longitudinal sibling study.Addictive behaviors reports · 2025Article
- Combined exposure to alcohol and cannabis during development: Mechanisms and outcomes.Alcohol (Fayetteville, N.Y.) · 2023Review
- The effects of cannabis use on physical health: A co-twin control study.Drug and alcohol dependence · 2022Article
- The Neurocognitive Effects of Cannabis Across the Lifespan.Current behavioral neuroscience reports · 2021Article
Corrections and comments
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Authors and funding
11 authors at 2 institutions in 1 country.
Funding
Abstract
aimsTo examine whether moderate adolescent cannabis use has neurocognitive effects that are unexplained by familial confounds, which prior family-controlled studies may not have identified.
designA quasi-experimental, sibling-comparison design was applied to a prospective, observational study of adolescents with moderate cannabis use. Participants were recruited from 2001 to 2006 (mean age = 17 years). A second wave of data was collected from 2008 to 2013 (mean age = 24 years).
settingTwo US metropolitan communities.
participantsA total of 1192 adolescents from 596 families participated in this study. Participants were primarily male (64%) and racially and ethnically diverse (non-Hispanic white = 45%). A sibling in each family was a clinical proband identified due to delinquent behaviors. Whereas prior family-controlled studies have used samples of primarily infrequent cannabis users (mean = 1-2 days/month), participants here endorsed levels of cannabis use comparable to findings from epidemiological cohort studies (mean = 7-9 days/month). MEASUREMENTS: Semi-structured clinical interviews assessed drug use, and a neuropsychological battery assessed cognitive abilities. Covariates included age at assessment, gender and alcohol use.
findingsAfter correcting for multiple testing, a greater frequency and earlier onset of regular cannabis use were associated with poorer cognitive performance, specifically on tests of verbal memory. Further, after accounting for familial factors shared by siblings and alcohol use, poorer verbal memory performance was still associated with greater life-time frequency of cannabis use at wave 1 [b = -0.007 (-0.002, -0.012), adjusted P = 0.036]; earlier cannabis use at wave 2 [b = -0.12 (-0.05, -0.19), adjusted P = 0.006; b = -0.14 (-0.06, -0.23), adjusted P = 0.006]; and greater frequency of past 6 months use at wave 2 [b = -0.02 (-0.01, -0.03), adjusted P = 0.002; b = -0.02 (-0.01, -0.03), adjusted P = 0.008].
conclusionsModerate adolescent cannabis use may have adverse effects on cognitive functioning, specifically verbal memory, that cannot be explained by familial factors.
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