Peer-reviewed article
Update on ADHD genetics: A practitioner's perspective: Mise à jour sur la génétique du TDAH : le point de vue d'un praticien.
Russell Schachar, Jennifer Crosbie, Paul D Arnold, Christie L Burton ·
Summary
Written by AI, not yet AICS's view · claude-haiku-4-5-20251001This is a clinical review article about the genetics of ADHD for healthcare practitioners. It summarizes research on heritability, genetic variants, and gene-environment interactions in ADHD. The article advises clinicians that while ADHD has a strong genetic basis, there are no diagnostic genetic tests, and assessment should focus on functional impairment and clinical history rather than genetic testing.
Key points
- ADHD is highly heritable at approximately 70%, comparable to other major neuropsychiatric conditions
- Thousands of common genetic variants contribute small effects to ADHD risk (polygenic inheritance)
- Rare copy number variants are more frequent in ADHD than in controls and overlap with autism variants
- There are no diagnostic genetic tests for ADHD; assessment should prioritize functional impairment and clinical history
- CYP2D6 genotyping is supported for atomoxetine dosing, but routine genetic testing for stimulant selection is not justified
Limitations
This is a clinical review synthesizing existing literature rather than a primary study, so it does not present new empirical evidence or evaluate any specific intervention. It focuses on clinical practice implications for healthcare professionals rather than on child well-being outcomes or intervention effectiveness.
Abstract
BackgroundAttention-deficit/hyperactivity disorder (ADHD) is a common neurodevelopmental condition characterized by early-onset inattention, hyperactivity, and impulsiveness. Affecting 5% to 10% of youth and persisting into adulthood in ∼6%, ADHD is frequently discussed in genetic terms by patients and their families, making it essential for clinicians to understand current genetic evidence.ObjectiveTo summarize contemporary genetic findings relevant to ADHD across the lifespan and provide practical guidance for clinicians on assessment, treatment, and psychoeducation.Scope and methodsThis focused narrative review integrates evidence from family and twin studies, genome-wide association studies (GWAS), copy number variants (CNVs), polygenic risk scores (PRS), and Mendelian randomization (MR), as well as pharmacogenetics and studies of gene-environment interplay.FindingsADHD is highly heritable (∼70%), comparable to other major neuropsychiatric conditions. GWAS reveals that thousands of common variants collectively contribute to risk (i.e., polygenic), though each has a small effect. Rare CNVs are more frequent in ADHD than controls and overlap with CNVs in autism. Genetic findings implicate neurodevelopmental pathways expressed in early brain and frontal cortical circuits. ADHD genetic risk correlates with cognitive traits, risk-taking behaviours, and multiple psychiatric and physical health outcomes. Gene-environment correlations and interactions influence risk and course. Pharmacogenetic evidence supports CYP2D6 genotyping for atomoxetine dosing; routine genetic testing for stimulant selection is not justified.Clinical implicationsThere are no diagnostic genetic tests for ADHD. Assessment should prioritize functional impairment, developmental and family history, and comorbidity. Psychoeducation should emphasize modifiable risks and the interplay of genes and the environment. While genetic insights may eventually refine diagnosis and personalized care, current best practice relies on comprehensive clinical evaluation and multimodal management.ConclusionGenetic research confirms ADHD's neurodevelopmental basis, continuity across the lifespan, and overlap with other neurodevelopmental conditions of childhood. Clinicians can use these insights for counselling and risk monitoring while avoiding over-reliance on genetic testing outside targeted pharmacogenetic use.