An epidemiological investigation of minimal brain dysfunction in six elementary schools in Beijing.

Six elementary schools from urban, suburban and mountain areas of Beijing (containing 2770 school children) were screened with a standardized questionnaire and each suspected case was interviewed to determine whether diagnostic criteria were met for attention deficit disorder with hyperactivity (DSM-III), with some cultural modification. The MBD prevalence rate was 3.1% in the urban, 7.8% in the suburban and 7.0% in the mountain area. Lower rates were found in the families of scientific and technical professionals or in those with higher education than others. The mean score or the severity of some clinical manifestations of MBD children showed differences in families with different occupations or educational levels. Social environmental factors were considered to play an important role in the development of MBD, which is possibly based on biological factors.