There is growing interest in children with behavioral and emotional disorders. Research has not only suggested that the number of impaired children is on the rise in Western societies (Rutter & Smith, 1995), but that they are in need of early detection and treatment to prevent future difficulties in adaptation and integration into society (Loeber & Farrington, 1998).
However, estimating the number of impaired children in general populations is not easy. Although there is a growing consensus that often some kind of neurologicaland/or biochemical process must be involved, the biological causes of childhood disorders still remain elusive (Grodzinsky & Barkley, 1999; Mash & Barkley, 2006; Sergeant et al., 2002). Until confirmed medical markers are found, the diagnosis can be established only at the behavioral level. To this end, clinicians and epidemiologists have to rely on the behavioral reports of parents, teachers, caretakers, and others.
Many rating scales can be used to assess behavioral and emotional problems in children and to estimate the number of impaired children in populations (Collett et al., 2003; Myers & Winters, 2002b). However, these scales often use different definitions of target problem behaviors, different criteria for impairment, and different sources of information, such a parents, teachers or mental health professionals. This has resulted in large variations of the prevalence estimates of childhood disorders in general populations (Angold et al., 1999; Swanson et al., 1998).
Moreover, most studies have not yet been based on the behavioral symptoms of the DSM-IV, which is an important frame of reference for mental health professionals in Western countries. As a result, DSM-IV-related estimates of the number of children displaying childhood psychiatric disorders are lacking.
The purpose of this study was to estimate the number of children in the general Dutch youth population displaying the symptoms of childhood psychiatric disorders as referenced in the DSM-IV. To this end, parents were asked to complete a questionnaire comprising the core symptoms of the major DSM-IV childhood disorders.
School directors in a random sample of Dutch primary and secondary schools were informed of the study and asked to deliver a letter to the parents of their pupils. This letter explained the purpose of the research, specified the requested parental contribution, and explained the anonymous nature of the study. Parents were asked to return written consent to participate in the study. About 5,000 families received this request, of which 2,536 consented to participate. To determine the agreement in parental ratings, the parents received two questionnaires, one for the father and one for the mother, with a re quest to complete the rating scales for their child independently of each other on the same day. To determine the stability of the ratings over time, the parents were asked to complete the same questionnaire again three weeks later. Parents who agreed to participate in this follow-up part of the study received a new set of questionnaires. The data-gathering took place in 2004.
Subjects and Methods
The sample consisted of 2,536 schoolchildren between 4 and 18 years of age (M = 10.1 years, SD = 3.2 years), of whom 51% were boys and 49% girls; 65% attended schools for primary education, 31% for secondary education, and 4% for special education. About 84% of the children lived in a family with two parents, 14% in a one-parent family, and 2% in residential institutions. The educational background of the families was: 27% of the primary caretakers completed education at lower levels, 49% at moderate levels, and 24% completed higher education. These demographic characteristics are similar to those of the general Dutch youth population (CBS, 2004). This suggests that the sample reflects this population sufficiently. …