title: [The attention deficit hyperactivity disorder  myth or reality?].
abstract: BACKGROUND
  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.
  
  
  OBJECTIVE
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Hospital Universitario de Maracaibo. Facultad de Medicina. La Universidad del Zulia, Maracaibo, Zulia, Venezuela. jokar@telcel.net.ve
authors.forename: J A
authors.initials: JA
authors.lastname: Peña
authors.forename: C
authors.initials: C
authors.lastname: Montiel-Nava
mesh_terms: D001289:Attention Deficit Disorder with Hyperactivity / Q000145:classification / Q000453:epidemiology / Q000503:physiopathology; D003937:Diagnosis, Differential; D006801:Humans; D015203:Reproducibility of Results; D012959:Socioeconomic Factors; D014687:Venezuela / Q000453:epidemiology