[The attention deficit hyperactivity disorder myth or reality?]

The attention deficit hyperactivity disorder (ADHD) has been defined as a disorder of self control characterized clinically by a short attention span, excessive motor activity and poor impulse control.

The main objective is to describe how methodological difficulties related to the design of epidemiological studies make an important contribution to the group of heterogeneous data which might lead to doubts regarding the validity of ADHD in children. In recent decades the psychiatric definition of this disorder has varied. This has affected the number and combination of clinical signs necessary for diagnosis of ADHD. The variation in the prevalence rates of the disorder reported in different studies is largely due to these changes. Other factors involved are related to the assessment methods, the type of sample (clinical or community), the source of information (parents, teachers and/or children) and sociocultural characteristics.

ADHD is a valid disorder. It cannot be considered to be a myth since there is considerable evidence of its existence and clinical characteristics in children in different countries.