Even at early stages of development, ADHD has high rates of comorbidity and a significant impact on school performance and family health.

The findings indicate that there are some differences in the prevalence rates of preschool psychopathological disorders between rural and urban Spanish areas.

The prevalence of preschool major depressive disorder (MDD) was studied in the community. The whole population of children between 3 and 6 years attending preschool nurseries in three areas (one urban, one rural and one suburban) in Spain (n = 1,427) were contacted. Selection was by a two-stage procedure. At stage I, the ESDM 3-6, a screening measure for preschool depression, was used to identify a sample for more intensive interviewing. Sensitivity and specificity of the cut-off point of the ESDM 3-6 had been previously tested in a pilot study (n = 229). During the first stage, 222 preschool children (15.6%) were found to be probable depressives, because they scored 27 or more, the cut-off used. At stage II, the children were interviewed and diagnosed by the consensus of two clinicians, blind to the ESDM 3-6 results. DSM-IV diagnostic criteria were used to define caseness. A total of 16 children (1.12%) met the MDD criteria. The prevalence by areas was urban 0.87%, rural 0.88%, suburban 1.43%. Sex distribution prevalence was 1:1. This study is a contribution to the scarce epidemiology of preschool depression in the community.

Many researchers have studied somatic symptoms in children. However, its association with severe mood dysregulation (SMD) is poorly known. The aim of this study is to detect the presence of SMD in preschool children and to know the prevalence of somatic symptoms and associations with psychopathology, SMD, and aggressiveness. The study population consists of children between 3 to 6 years of age enrolled in Barcelona's kindergarten schools (n = 319). Their parents completed questionnaires about the presence of somatic symptoms in children, absences from school and pediatric visits, child psychiatric symptoms, presence of symptoms of SMD, and aggressiveness. Teachers were also informed about SMD and aggressiveness. Children who complained frequent somatic symptoms (three or more in the last 2 weeks) were compared with those who did not. Two hundred five children (64.3%) reported at least one physical complaint in the 2 weeks preceding the study. One hundred participants (31.3%) reported frequent somatic complaints. Positive associations were found with anxiety symptomatology, separation anxiety, social phobia, pediatric visits, and school absences, but not with aggressiveness or SMD symptoms. Somatic symptoms are common in a sample of preschool children but do not show a positive association with the symptoms of SMD.

Objective: to establish the prevalence and associations of peer aggression as manifested in preschool children, in community-based populations and to study links with DSM-IV externalizing diagnoses. Method: Subjects were 1,104 children, 3-to-5-year-olds attending rural and urban pre-schools classes. Teachers completed the Peer Conflict Scale (PCS) to inform about direct physical and verbal aggression, object aggression and symbolic aggression and the questionnaire on psychopathology ECI-4. Results: 6.6% (n = 73) had at least one positive item on the PCS. This percentage dropped to 2.6% (n = 29) if we take into account a minimum of three positive items. Physical direct aggression was the more prevalent type of aggressive behavior, followed by verbal aggression, object aggression and symbolic aggression. Significant differences by gender and age were found. Peer aggression was associated with male gender from three years of age. Physical, object and verbal aggressive behavior was linked with externalizing disorders. This association was very strong with oppositional disorder. Conclusions: The present research with a Spanish population confirms the existence of peer aggression in preschoolers and the gender differences. Our chief contribution is about the age of emergence of sex differences and gender differences in different types of peer aggression. Keywords: preschool peer aggression, preschool externalizing disorders, peer conflict scale (PCS)Objetivo: Determinar la prevalencia de agresión preescolar hacia iguales en la comunidad y su correlación con categorías externalizantes del DSM-IV. Método: La muestra fue de 1104 niños de 3 a 6 años, procedentes de aulas preescolares urbanas y rurales. Se aplicó a los maestros la Peer Conflict Scale (PCS), para recabar información de agresiones físicas directas, verbales, con objetos y simbólicas, y el cuestionario de psicopatología ECI-IV. Resultados: Un 6.6% (n = 73) puntuó positivamente por lo menos en un item de la PCS. Este porcentaje decreció hasta un 2.6 % (n = 29) con una definición de caso más exigente (mínimo tres ítems positivos). La agresión física directa fue la forma más frecuente de agresión seguida de agresión verbal y agresión con objetos. Hubo diferencias significativas según edad y sexo. La agresión dirigida a iguales se asocia al sexo masculino desde los 3 años. La agresión física directa, con objetos y verbal correlaciona con trastornos externalizantes, principalmente con trastornos oposicionistas. Conclusiones: Esta investigación en población española confirma la existencia de agresividad hacia iguales en preescolares así como diferencias según sexo. Nuestra principal aportación es haber encontrado diferencias de sexo en el inicio y en los tipos de agresividad hacia iguales. Palabras clave: agresión preescolar hacia iguales, trastornos preescolares externalizantes, PCS