The manual distinguishes between three
subtypes of the disorder: predominantly hyperactive/impulsive
type, predominantly inattentive type and combined type. In
order to reach diagnosis according to the latest version of the
DSM, symptoms must have onset before the age of 12 (rather
than an age 7 cut-off for symptom-related impairment in
DSM-IV), be pervasive across settings (e.g. home and school)
and associated with substantial impairment in functioning
(APA 2013).