The primary features of ADHD include inattention and hyperactive-impulsive behavior. ADHD symptoms start before age 12, and in some children, they're noticeable as early as 3 years of age. ADHD symptoms can be mild, moderate or severe, and they may continue into adulthood.
There are three subtypes of ADHD:
- Predominantly inattentive. The majority of symptoms fall under inattention.
- Predominantly hyperactive/impulsive. The majority of symptoms are hyperactive and impulsive.
- Combined. This is a mix of inattentive symptoms and hyperactive/impulsive symptoms.