Attention deficit/hyperactivity disorder (ADHD) is a behavioral condition characterized by inattention, impulsivity, and hyperactivity. Most people experience these behaviors from time to time, but in ADHD, they are more severe, happen more often, and interfere with a person’s ability to function socially, at school, or in the workplace.[1] ADHD is divided into three subtypes by predominant symptomatology: Inattentive (ADHD-I), Hyperactive-Impulsive (ADHD-HI), and Combined (ADHD-C). Symptom clusters can change as individuals mature and develop.[2]
What is ADHD?
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•Last Updated: May 16, 2025
Attention deficit/hyperactivity disorder (ADHD) is a behavioral condition marked by severe inattention, impulsivity, and hyperactivity that disrupts social, academic, or workplace functioning. It has 3 subtypes — inattentive, hyperactive-impulsive, and combined — based on predominant symptoms, and symptom clusters may change as individuals mature.