Is Intelligence a Vulnerability Factor for Functional Somatic Symptoms in Adolescents? To make unexplained symptoms more explainable.

Introduction: Functional somatic symptoms (FSS) are somatic symptoms of unknown organic pathology. FSS in adolescents are frequently seen, but the exact etiology of FSS is poorly understood. A recent study demonstrated the negative association between intelligence and FSS in adults. We hypothesized that this negative association between intelligence and FSS will also be found in adolescents. Furthermore, we hypothesized that poor school performance, could cause psychological distress, and could be a mediator in the association between intelligence and FSS. In addition, we hypothesized that the association between intelligence and FSS in adolescents is only true when the parental intellectual level is higher than the intelligence of their adolescent child. Methods: The present study was performed in a cohort from TRacking Adolescents’ Individual Lives Survey (TRAILS). Intelligence was measured in 2230 adolescents (at the age of 10 till 12 years) by the Wechsler Intelligence Scale for Children Revised (WISC-R) at baseline. FSS was measured with the somatic complaints subscale of the Youth Self Report (YSR) at baseline and at follow-up, approximately two years later. School performance and the intellectual level of the parents were both measured with questionnaires. Results: There was no association between intelligence and FSS at baseline, but there was a significant negative association between intelligence and FSS at follow-up (β= -0.107, t= -5.296, p= 0.000). School performance did not mediate the association between intelligence at baseline and FSS at follow-up. In addition, the association between intelligence at baseline and FSS at follow-up was only significant in children with parents having a high intellectual level (follow-up: β= -0.107, t= -5.296, p=