There are main diagnostic criteria:
-onset before age 12 years old
-duration greater than 6 months
-children must have at least six symptoms from the inattention and/or hyperactive/impulsive symptom list, while older adolescents and adults must have at least five
-several symptoms must be present in two or more settings and interfere with functioning
-symptoms that do not occur exclusively during the course of schizophrenia or other psychotic disorder and are not better accounted for by another mental disorder, such as depression.
-There are no blood, genetic, or neuroimaging tests available to diagnose ADHD.
-A detailed family, medical, and psychiatric history should be completed. The medical history should cover the prenatal, perinatal, toddler, and preschool phases of development.