Based on these criteria, 3 types of ADHD are identified:
ADHD, Combined Type: if both the inattention and hyperactivity/impulsivity criteria are met for the past 6 months
ADHD, Predominantly Inattentive Type: if the inattention criteria are met but the hyperactivity/impulsivity criteria are not met for the past 6 months
ADHD, Predominantly Hyperactive-Impulsive Type: if the hyperactivity/impulsivity criteria are met but the inattention criteria are not met for the past 6 months.
For more information about diagnosing ADHD, see the eMedTV article ADHD Doctor.