[Neurobiology of hyperactivity disorder]

Hyperactivity disorder (HAD) is chiefly characterised by excessive motor activity that is maintained throughout the whole day. Despite the fact that the first clinical descriptions of HAD date from the early 20th century, we still do not know much about the exact nature of this neurobiological disorder.

The different denominations used to refer to this alteration have not exactly helped to shed light on the disorder. Two terms are currently employed for it, attention deficit hyperactivity disorder (ADHD), which is characterised by inattention, impulsiveness and hyperactivity, and HAD. In either case, it would be the hyperactive behaviour that would lead parents to seek specialised help. Since there are no biological markers, children with hyperactivity are diagnosed through interviews and questionnaires administered to the children, the parents and teachers. This has sometimes led to children with different behavioural manifestations being grouped under a same heading, as regards the aetiology of their disorder or how they respond to treatment.

It is therefore obvious that there is a need to establish subgroups that enable the neurobiological features of HAD to be clearly defined. An approach to the study of this disorder from different perspectives and methodologies (genetics, neuroanatomy, neurochemistry or neurophysiology) that allow long term efficient therapeutic alternatives to be developed would undoubtedly make an important contribution in this direction.