What Is ADHD? Meaning, Symptoms & Tests

Attention deficit hyperactivity disorder (ADHD) is a neurological disorder that impacts the parts of the brain that help us plan, focus on, and execute tasks. ADHD symptoms vary by sub-type — inattentive, hyperactive, or combined — and are often more difficult to diagnose in girls and adults. Here, we review the symptoms, causes, types, and tests associated with attention deficit hyperactivity disorder.