Heart rate variability in ADHD: a clinical perspective on autonomic regulation, emotional dysregulation, and treatment tolerability

Attention-deficit/hyperactivity disorder (ADHD) is increasingly understood as a condition involving difficulties in cognitive, emotional, behavioural, and physiological self-regulation. Heart rate variability (HRV) has been proposed as a non-invasive index of autonomic regulation and vagal flexibility, but its interpretation in ADHD remains complex. This clinical perspective examines the relevance of HRV to autonomic dysregulation, emotional dysregulation, and treatment tolerability in ADHD. A narrative evidence synthesis was conducted using targeted searches of PubMed/MEDLINE, Embase, and PsycINFO, supplemented by manual screening of relevant reviews and empirical studies. Current evidence suggests that altered autonomic regulation may be present in some individuals with ADHD, particularly under cognitive, emotional, or stress-related demands. Reduced vagally mediated HRV appears more consistently in task-related contexts than during resting-state assessment, although findings remain heterogeneous across developmental stage, medication status, comorbidity, recording protocols, and HRV indices. Emotional dysregulation may represent one clinically meaningful pathway through which autonomic vulnerability becomes visible. On this basis, we propose a phenotype-informed autonomic framework that distinguishes patients with more evident hyperarousal, emotional reactivity, and treatment sensitivity from those with more compensated regulatory profiles. This framework is intended as a clinical and research concept rather than a diagnostic model. HRV should therefore not be regarded as a diagnostic biomarker or stand-alone guide for treatment selection. Future studies should use standardised HRV protocols, longitudinal designs, and careful clinical phenotyping to determine whether autonomic measures can improve assessment, treatment monitoring, or risk stratification in ADHD.