Autism spectrum disorder and attention-deficit/hyperactivity disorder in early childhood: A review of unique and shared characteristics and developmental antecedents

Abstract

Autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD) have overlapping characteristics and etiological factors, but to which extent this applies to infant- and preschool age is less well understood. Comparing the pathways to ASD and ADHD from the earliest possible stages is crucial for understanding how phenotypic overlap emerges and develops. Ultimately, these insights may guide preventative and therapeutic interventions. Here, we review the literature on the core symptoms, temperament and executive function in ASD and ADHD from infancy through preschool age, and draw several conclusions: (1) the co-occurrence of ASD and ADHD increases with age, severity of symptoms and lower IQ, (2) attention problems form a linking pin between early ASD and ADHD, but the behavioral, cognitive and sensory correlates of these attention problems partly diverge between the two conditions, (3) ASD and ADHD share high levels of negative affect, although the underlying motivational and behavioral tendencies seem to differ, and (4) ASD and ADHD share difficulties with control and shifting, but partly opposite behaviors seem to be involved.

Twenty years of research on attention-deficit/hyperactivity disorder (ADHD): looking back, looking forward

“…Another pivotal change in DSM-5 is the removal of the veto around the dual diagnosis of ADHD and autism spectrum disorders (ASD) that was present in previous editions of the DSM. Unlike the age of onset and symptom number changes this change is supported by a significant body of research (see ref 6). Finally, the (sub)types of ADHD defined in the DSM-IV-(TR) were replaced by the notion of different presentations.…”

Inattention and hyperactivity in association with autism spectrum disorders in the CHARGE study

“…To date, studies of individuals with ASD and ADHD symptoms suggest there is greater social and cognitive impairment, poorer outcomes, and higher rates of internalizing and externalizing problems in children with comorbid ADHD and ASD than in those with ASD alone (Holtmann et al 2007; Rao and Landa 2014; Visser et al 2016). However, most prior studies have had modest sample sizes, lacked consideration of a range of potentially confounding factors, and have focused on children of school-age or older (Ehlers et al 1997; Geurts et al 2004; Corbett and Constantine 2006; Lundervold et al 2012; Jang et al 2013; Rao and Landa 2014).…”

“…However, most prior studies have had modest sample sizes, lacked consideration of a range of potentially confounding factors, and have focused on children of school-age or older (Ehlers et al 1997; Geurts et al 2004; Corbett and Constantine 2006; Lundervold et al 2012; Jang et al 2013; Rao and Landa 2014). The few studies focusing on young children have been based on clinically-ascertained samples (Visser et al 2016), which likely have limited generalizability given noted skewed severity distributions in such samples (Rao and Landa 2014). Only two studies to date have examined ADHD symptoms in children under age 5 with ASD drawn from community-based samples, and both were extremely small (Leyfer et al 2006; Rao and Landa 2014).…”

Autism as an Infantile Post-trauma Stress Disorder: A Hypothesis

“…According to results of a previous research, the comorbidity of ASD and ADHD estimates range from 37%-78% [14]. The attention problem is considered as the common pathway to ADHD and ASD [15].…”