Abstract
Attention deficit hyperactivity disorder is most commonly diagnosed at school age, when it reveals itself through the difficulties children face in connection with such things as attention deficit, excessive hyperactivity and impulsiveness, all of which may problematize studying at school. It should be noted that the initial symptoms of ADHD, which may already be present in early childhood, can alter with age, and may also change according to situation. The aim of this article is to explore the diagnostic criteria for attention deficit hyperactivity disorder while giving special consideration to the different symptoms occurring at successive stages of child development and also outlining those behavioural and emotional disorders that co-occur with ADHD.