How common are symptoms of ADHD in typically developing preschoolers? A study on prevalence rates and prenatal/demographic risk factors.

According to the Diagnostic and Statistical Manual of Mental Disorders - Fourth Edition (DSM-IV - American Psychiatric Association, 1994), one of the diagnostic criteria for attention deficit hyperactivity disorder (ADHD) is the presence of symptoms of inattention and/or hyperactivity-impulsivity before the age of 7 years. In contrast to studies with older children, relatively little is known about ADHD symptoms in preschoolers. In order to address this issue, the present study was designed to investigate to what extent ADHD behaviors exist in a large community based group of preschoolers in the Netherlands. A second aim of this study was to shed light on the etiology of ADHD, by examining if and how a range of prenatal and demographic factors contribute to the prediction of ADHD behaviors in young children. Participants included 652 parents of children between the ages of 3 and 6 years. Parents were asked to complete two questionnaires: the Preschool Behavior Questionnaire (Smidts and Oosterlaan, 2005) and a background information questionnaire, specifically designed for this study. Findings from the present study show that ADHD symptoms are quite common in preschoolers, with approximately one-third of all ADHD behaviors listed in the Preschool Behavior Questionnaire being highly frequent in early childhood. It appears that hyperactive-impulsive symptoms are more common in preschoolers than inattentive behavior. For the purpose of an early identification of ADHD, this finding is particularly important, as it may be argued that inattentive behavior in preschoolers may be indicative of psychopathology. Significant predictors of ADHD behaviors included maternal smoking and alcohol, and illness of the mother during pregnancy; however, together these factors explained less than 10% of the variance.