Are ADHD and ASD Comorbid? The Problem of Medical Reductionism in ASD and ABA
The first challenge for this question is to correctly identify the meaning of medical comorbidity. Medical comorbidity is when one primary chronic diagnosis occurs with another but would also exist without the other. Comorbidity is 'the co-occurrence of two or more disorders in the same individual at the same point in time (https://www.sciencedirect.com/topics/neuroscience/comorbidity).'
As a familiar for instance, babies born with Down Syndrome can have serious defects to the ventricular wall in their heart which often requires more immediate and, sometimes, multiple surgeries to correct. The point is that correcting the heart defect does not change the diagnosis of Down Syndrome or how it will express in that individual. The baby with Down Syndrome also has a heart defect and each diagnosis is single from the other with a course of treatment fully independent of the other.
This discussion now moves to whether the long and hotly debated 'ADHD' diagnosis is comorbid in children with ASD; that is, does (can) ASD and ADHD exist as simultaneous but independent, primary diagnoses.
As a very relevant aside, the category of ADHD has long been up to intense debate with regards to whether or not it should even exist as a unique diagnosis based on the many confounds that impact on and can lead to related behavioral characteristics, adult and clinician perceptions of these characteristics and the subsequent diagnosis.
Lyon, Shaywitz, Fletcher & Olson (2001), in their chapter on 'Rethinking Learning Disabilities, ' a diagnosis also often closely linked with ADHD characteristics and diagnosis, wrote that LD has become a ‘sociobiological sponge’ which attempts to wipe up general education’s spills & cleanse its ills.' As Lyon et al, pointed, out, LD can sometimes be constructed by deficits in instruction. Similarly, characteristics of both ADHD and ASD can also be increased or decreased based on the efficacy of instructional strategies and practice.
This argument further connects to the category of ADHD in that the wide range of characteristics often lumped together and called 'ADHD" closely link to, are interwoven in and across a great many other areas of human need driven by genetics, context and social/environment.
Does this mean that at a percentage of younger children with ASD who tend to be extremely active, disinhibited/impulsive, hard to engage and sustain engagement also have 'ADHD?"
In consideration to medical comorbidity, it is more likely that some children with ASD tend towards these behavioral characteristics while many others simply do not. For many so identified children, it is more likely that attentional issues; disinhibition; executive processing et al. present as behavioral observations from one form of ASD. In this model, ADHD is not comorbid to ASD but additional characteristics (observations) of children who fall into a particular category of ASD.
A closely related problem when presuming medical comorbidity between ASD & ADHD is that such a presumption can very easily and quickly only further (mis)apply the highly problematic reductionist medical model to ASD.
Medical reductionism is not always a bad thing. For instance, children with juvenile diabetes only have so many treatments available. While bronchodilators work well for children with asthma, they won't do much for those with diabetes. In these circumstances, there is a much more limited range of diagnostic etiology and subsequent treatments. Neither ASD nor ADHD can be quite so clearly diagnosed and, once identified, services and support must be designed for each individual child based on a range of variables that must be specifically identified for that child.
In its increasing application to ASD and Applied Behavior Analysis, such medical reductionism poses more than a few significant risks. It's misapplication can routinely ignore environment/context relevance, behavioral function, differentiated/individualized instructional needs, ecological functional behavior assessment and, of particular importance, the many unique individual qualities of the child.
The view of a medical comorbidity between ASD and ADHD also leaves children with ASD more likely to be seen as having an 'illness' with behavioral analytic and instructional Best Practices replaced by a blend of pseudoscience and/or the more traditional reductionist medical model with its strong preference for an often overactive use of medication.