Novika Purnama Sari

It is well-known that families of children with autism experience a challenging journey. Yet, it is unknown to what extent the milder autism traits are associated with children’s academic achievement or with parental behavior and whether certain characteristics have a better predictive value for child autistic traits. Therefore, in this thesis, we investigated possible predictors and correlates of autism traits in children.

Starting with a brief overview of the autism history, chapter 1 introduces the continuum concept of autism traits in the general population as the main approach for the current thesis, and describes the history and current knowledge on the etiology of child autistic traits. Further, the aims and setting of this thesis are presented.

In chapter 2, we investigated child autistic traits during early childhood in relation to academic achievement. In addition, we also examined vocabulary skills and behavior problems as two potential mediators in the association of child autistic traits and academic achievement. Our findings showed that increased autistic traits predicted poorer academic achievement. Moreover, the association between child autistic traits and academic achievement was in part mediated by vocabulary skills and behavior problems in middle childhood.

In chapter 3, we examined whether nonverbal IQ, child sex, and externalizing problem behaviors moderated the association between child autistic traits and peer relationships. The results showed that less autistic traits predicted more peer acceptance and less peer rejection. Externalizing problems moderated the association between child autistic traits and peer relationships. Our findings showed that peer rejection remained relatively high for children with higher externalizing problems regardless of the autistic traits’ levels. Further, non-verbal IQ or child sex did not moderate the association between child autistic traits and peer relationships. Our findings in chapter 2 and 3 suggest that language skills such as vocabulary may aid children in understanding teacher’s instructions and that externalizing problems, such as frequent fighting, irritating the social environment, resulting in peer rejection.

In chapter 4, we explored the independent contribution of mother’s age at conception, mentalizing skills, and maternal autistic traits to the development of child autistic traits. Our findings suggested that the relationship between maternal age at conception fits a U-shaped pattern (quadratic relationship) with child autistic traits. Maternal autistic traits predicted autistic traits in children, and better maternal mentalizing skills were associated with less maternal autistic traits. Our findings regarding autistic traits in mothers may signal a genetic loading for autism.

In chapter 5, we explored maternal pre-pregnancy body mass index (BMI) as potential moderator in the association between maternal autistic traits and child autistic traits at three different timeframes (i.e., infancy, early childhood, early adolescence). We used two different cohorts; the Generation R study and Cambridge Ultrasound Siblings and Parents Project (CUSP). We found that higher maternal pre-pregnancy BMI was independently associated with more child autistic traits, yet we did not find a moderating effect of maternal pre-pregnancy BMI on the association between maternal autistic traits and child autistic traits.

In chapter 6, we examined the association among harsh parenting and autistic traits in mothers or in children. We found that higher levels of harsh parenting were associated with more autistic traits in mothers as well as in children.

In chapter 7, we compared pre-pandemic harsh parenting levels using the Generation R cohort and Covid-19 samples collected during the Covid-19 lockdown. We found that harsh parenting levels during the lockdown were significantly elevated compared to pre-pandemic levels. Taken together, our findings in chapter 6 and 7 might mean that Covid-19 pandemic has influenced parental behavior in almost every family, either in children with or without autism. As parental responses (i.e., coping strategies) may play a role in coping with parenting stress, parents-focused support should be enhanced.

Finally, in chapter 8 we summarize and interpret the main findings of the different studies, present methodological considerations, describe potential clinical implications, and provides directions for future scientific research.