Functional connectivity patterns differ as a function of co-occurring attentional problems in preschoolers with...

Symptoms of attention-deficit/hyperactivity disorder (ADHD) are common in children with autism spectrum disorder (ASD), and are associated with greater developmental challenges, poorer clinical outcomes, and alterations in functional connectivity (FC) of the brain. However, despite the consensus that ASD and other neurodevelopmental conditions emerge early in life, little is known about the trajectories of brain and behavioral development during the first years of life in children with ASD and co-occurring attention problems (AP).

In a sample of 122 young children (ages 1.5-5 years) with and without ASD, we examined whether toddlers and preschoolers with ASD and co-occurring AP already differ from peers with ASD without co-occurring AP on adaptive and developmental skills, ASD symptoms, and FC of the frontoparietal and salience networks, which have been previously linked to ADHD symptoms in older children with ASD and ADHD.

Results of general linear model analyses revealed lower developmental and adaptive skills across multiple domains in children with ASD and elevated AP compared with their peers with lower AP, despite equivalent levels of ASD symptoms. Further, children with ASD and elevated AP showed reduced FC within the frontoparietal network (p = .027), between the frontoparietal and language networks (p = .004), and the frontoparietal and default mode networks (p = .046) in comparison to their peers with lower AP. No group differences in FC of the salience network were observed (all p > .05).

These findings provide evidence that neurodevelopmental and behavioral differences in children with ASD and co-occurring AP emerge very early in life, before a reliable diagnosis of ADHD is typically made. Specifically, these results demonstrate that early inattention symptoms are associated with unique connectivity patterns in executive circuitry as early as the first years of life in toddlers and preschoolers with ASD, likely contributing to the phenotypic and neural heterogeneity recognized in autism. Thus, our results underscore the importance of considering co-occurring conditions early in developmental research and clinical care, as further understanding these trajectories can inform early interventions during the critical time period when they have the greatest potential for positive impact.