Attention deficit hyperactivity disorder (ADHD) is a common condition in childhood and has a great impact on the affected children and their environment. ADHD affects 3-5 % of Norwegian children, and persist into adulthood in 2/3 of the cases.A substantial discrepancy exists in the male-to-female ratio between clinically referred (9-10: 1) and community (2-3: 1) samples of children with ADHD which suggests an underidentification of girls compared to boys. These findings also raise concerns that referral bias may account for the gender differences in ADHD reported in the literature.
Hyperactivity, impulsivity and inattention are considered core symptoms in ADHD, with subtypes separated according to which set of features predominate.
Some studies suggest that there are differences in symptoms between girls and boys with ADHD with more boys being predominantly active and impulsive and more girls having inattentive problems. Some of these sex differences may be explained by differences in the general population with boys generally being more hyperactive and impulsive than girls. Other studies find no differences in symptoms between girls and boys with ADHD.
ADHD is frequently comorbid with a variety of psychiatric disorders. These include disruptive behavior disorders, affective disorders, anxiety disorder, tic disorder and substance abuse. The majority of all individuals with ADHD also meet criteria for at least one more (often two or three more) psychiatric disorders. This concerns both boys and girls. Several studies find that psychiatric comorbidity in ADHD children does not differ significantly by gender.