Genetic analysis supports ADHD as a causal risk factor for substance use disorders

GWAS analysis confirmed shared genetic architecture between ADHD and substance use disorders, with evidence that genetic liability to ADHD causally increases SUD risk, while lifetime cannabis use genetically influenced ADHD risk.

Vilar-Ribó, Laura et al.·American journal of medical genetics. Part B·2021·Moderate EvidenceCross-Sectional
RTHC-03596Cross SectionalModerate Evidence2021RETHINKTHC RESEARCH DATABASErethinkthc.com/research

Quick Facts

Study Type
Cross-Sectional
Evidence
Moderate Evidence
Sample
N=989

What This Study Found

The study confirmed a common genetic background between ADHD and SUD using both clinical (n=989) and population GWAS data. Mendelian randomization supported a causal effect of ADHD liability on SUD risk, and found a novel bidirectional effect where genetic liability for lifetime cannabis use influenced ADHD risk.

Key Numbers

Clinical sample: 989 subjects. Five SUD phenotypes tested: lifetime cannabis use, alcohol dependence, smoking initiation, cigarettes per day, and drinks per week. Shared genetic background confirmed for cannabis use, alcohol dependence, and smoking initiation.

How They Did This

Combined in-house clinical sample (989 ADHD subjects) with pre-existing GWAS datasets for five SUD-related phenotypes. Used polygenic risk score analysis, genetic correlation, and Mendelian randomization to assess shared genetics and causal relationships.

Why This Research Matters

Understanding the genetic basis of ADHD-SUD comorbidity can improve screening and treatment approaches, particularly the novel finding that cannabis use liability may itself influence ADHD.

The Bigger Picture

Nearly one in four people with substance use disorders also has ADHD. These genetic findings support screening for ADHD in all SUD patients and monitoring substance use in ADHD patients.

What This Study Doesn't Tell Us

Cross-sectional genetic analysis cannot capture environmental interactions. Clinical sample was modest in size. Mendelian randomization assumptions may not fully hold.

Questions This Raises

  • ?How does the bidirectional genetic relationship between cannabis use and ADHD manifest clinically?
  • ?Could early ADHD treatment reduce the genetic risk pathway to substance use disorders?

Trust & Context

Key Stat:
Genetic liability to ADHD causally increases substance use disorder risk
Evidence Grade:
Combines clinical and population genetic data with Mendelian randomization, though limited by sample size and cross-sectional design.
Study Age:
Published in 2021.
Original Title:
Genetic overlap and causality between substance use disorder and attention-deficit and hyperactivity disorder.
Published In:
American journal of medical genetics. Part B, Neuropsychiatric genetics : the official publication of the International Society of Psychiatric Genetics, 186(3), 140-150 (2021)
Database ID:
RTHC-03596

Evidence Hierarchy

Meta-Analysis / Systematic Review
Randomized Controlled Trial
Cohort / Case-Control
Cross-Sectional / ObservationalSnapshot without intervening
This study
Case Report / Animal Study

A snapshot of a population at one point in time.

What do these levels mean? →

Frequently Asked Questions

Is the link between ADHD and substance use genetic?

Partially. This study found shared genetic variants between ADHD and multiple substance use phenotypes, including cannabis use, alcohol dependence, and smoking initiation.

Does cannabis use genetically influence ADHD?

The study found novel evidence that genetic liability for lifetime cannabis use was associated with ADHD risk, suggesting a bidirectional genetic relationship.

Read More on RethinkTHC

Cite This Study

RTHC-03596·https://rethinkthc.com/research/RTHC-03596

APA

Vilar-Ribó, Laura; Sánchez-Mora, Cristina; Rovira, Paula; Richarte, Vanesa; Corrales, Montserrat; Fadeuilhe, Christian; Arribas, Lorena; Casas, Miquel; Ramos-Quiroga, Josep Antoni; Ribasés, Marta; Soler Artigas, María. (2021). Genetic overlap and causality between substance use disorder and attention-deficit and hyperactivity disorder.. American journal of medical genetics. Part B, Neuropsychiatric genetics : the official publication of the International Society of Psychiatric Genetics, 186(3), 140-150. https://doi.org/10.1002/ajmg.b.32827

MLA

Vilar-Ribó, Laura, et al. "Genetic overlap and causality between substance use disorder and attention-deficit and hyperactivity disorder.." American journal of medical genetics. Part B, 2021. https://doi.org/10.1002/ajmg.b.32827

RethinkTHC

RethinkTHC Research Database. "Genetic overlap and causality between substance use disorder..." RTHC-03596. Retrieved from https://rethinkthc.com/research/vilar-ribo-2021-genetic-overlap-and-causality

Access the Original Study

Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.

This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.