Differential diagnosis of autism spectrum disorder, intellectual disability and attention-deficit hyperactivity disorder (ADHD)

Abstract

Purpose Professionals working with community populations are often presented with complicated cases where it is difficult to determine which diagnosis or diagnoses are appropriate. Differentiating among neurodevelopmental disorders such as autism spectrum disorder (ASD), attention-deficit/hyperactivity disorder and intellectual disability can be a complex process, especially, as these disorders have some overlapping symptoms and often co-occur in young children. This series of case studies aims to present commonly overlapping symptoms in children who present to clinics with developmental concerns. Design/methodology/approach This paper presents three case studies that were completed at a free community ASD screening clinic in Southern California. Findings The case studies have common presenting behaviors and symptoms (e.g. social communication difficulties) that often co-occur across diagnoses; explanations for the final diagnoses are given in each case. Research limitations/implications Conclusions from these three cases cannot generalize to all children being seen in clinics for neurodevelopmental concerns. Practical implications This series of case studies highlights commonly overlapping symptoms in children who present for differential diagnosis with social and/or behavioral concerns. Implications for educational placement and intervention are discussed. Social implications These cases highlight the challenges involved in the differential and dual diagnostic process for young children with developmental concerns. Diagnostic considerations can affect later educational placement and opportunities for socialization. Originality/value This series of case studies provide practical information for clinicians about how to effectively differentiate between commonly occurring neurodevelopmental disorders, particularly given recent changes to the Diagnostic and Statistical Manual, 5th edition (DSM-5).

Diagnosis of Co-occurring Autism and Attention Deficit Hyperactivity Disorder

“…The number of other conditions, which statistically are more likely to co-occur with autism and ADHD than a non-clinical population, are not only other neurodevelopment diagnoses, such as dyslexia and intellectual impairment, but also other physical, genetic and related conditions, such as sleep, sensory processing issues, gastrointestinal difficulties and epilepsy (Jensen & Steinhausen, 2015;Neumeyer et al, 2019;Soke et al, 2018). All of these additional issues have the potential to mask, overshadow, or substitute for the possibility of correct diagnosis of autism or ADHD (Heyman et al, 2022). In addition there are some common characteristics shared across diagnostic categories and also heterogeneity in symptom profile expected within diagnostic categories (Uddin et al, 2019).…”

“…This means that there are many behavioural characteristics that are not uniquely indicative of one specific diagnosis. When diagnostic case complexity occurs, there are often social difficulties and atypical attention characteristics as part of the complex profile (Heyman et al, 2022). For a child to fulfil the criteria of autism + ADHD, the child must be presenting with multiple complex traits, which are not better explained by a single diagnosis.…”

“…The vignettes used in this study were based on research into behaviour that is likely to co-occur across neurodevelopmental conditions (Heyman et al, 2022;Soke et al, 2018;Yorke et al, 2018) as well as an amalgamation of cases experienced in clinical practice by the authors. The symptoms in the vignette were designed to illustrate a complex case presentation rather than clear examples of DSM 5 criteria and, as such, there was no one "correct" response (American Psychiatric Association, 2013) (see tables 6.1 and 6.2).…”

“…The difficulties in diagnosing co-occurring autism and ADHD are reflected in a delayed autism diagnosis of over a year later on average when ADHD is present . This delay may be partially due to "diagnostic overshadowing", where autism symptoms are masked by a child's more apparent ADHD symptoms (Gipson et al, 2015;Soke et al, 2018) or "diagnostic substitution", where a child is given a diagnosis as indicated by symptoms presentation, but a co-occurring diagnosis or other developmental disability covers a more comprehensive symptom profile of the child (Heyman et al, 2022). Clinicians may also find one diagnosis that fits and fail to consider further diagnoses (Gipson et al, 2015;Soke et al, 2018).…”

“…Clinicians may also find one diagnosis that fits and fail to consider further diagnoses (Gipson et al, 2015;Soke et al, 2018). Case-complexity is usually defined by the presence of co-occurring symptoms, which complicate a differential diagnosis or diagnoses (Heyman et al, 2022).…”