A Rant About Russ Barkley and OCD/ADHD Comorbidity

In my search to better understand my symptoms, I came across a video by Russell Barkley titled “OCD and ADHD.” Barkley is an expert in ADHD, mostly known for his diagnostic tools and talks. While watching this video, I realized that, in contrast to other sources, his language was significantly more dismissive of the comorbidity. I’m not claiming to know the subject better than an expert, but given that I had a bit of background knowledge, his presentation felt a little… off. Let’s start with a bit of important context: 1. ADHD occurs in around 7-8% of children and 3-5% of adults. OCD occurs in around 1-2% of children and 2-3% of adults. 2. People with OCD are 2-5x more likely to have ADHD (~25% of children, ~8% of adults), figures vary widely across studies but mostly land within this range. However, it is important to note that the other direction, ADHD -> OCD, is underexplored and, counterintuitively, people with ADHD are only ~2x more likely to have OCD. In other words, it’s “lopsided,” as Barkley explains in the video. 3. ADHD and OCD lay on opposite ends of the compulsive-impulsive continuum (which ranges from compulsive to impulsive). Barkley touches upon this through the lens of brain differences, but his claims are a bit oversimplified, framing OCD as uniformly larger and overactive in frontal/cingulate regions which isn’t well-supported (to his credit, the smaller basal ganglia in ADHD, larger in OCD is well-supported). Again, supporting that the two disorders are “opposites” by nature. The meta-analysis that best supports the basal ganglia differences notes that both disorders involve prefrontal underactivity, but it only aims to understand the “shared and differential brain abnormalities in relatively pure disorders” The authors note “future studies should test to what extent the comorbid cases with both ADHD and OCD differ from the individual disorders.” It’s important to note that these are group-level patterns in pure cases! There is yet to be a study that looks into the brains of individual comorbid patients (well, in terms of neuroimaging) When he presents those facts, he states “notice that looking at each disorder, the majority of people with one disorder do not have the other disorder but some people do.” This phrasing is odd, because rather than emphasizing the significant 2-5x increase in risk, he words it as a “majority of people” not having it. This is technically correct, but a little odd. He continues, and introduces a caveat: “Complicating matters even more, OCD is substantially related to tic disorders and Tourette's syndrome which we know also coexists with ADHD. So is that the reason for this overlap if we control for tic and Tourette syndrome, would the overlap go away? I don't know, I haven't seen any studies that have done so I certainly would think that it would diminish it somewhat" This introduction of a third variable made little-to-no sense to me, as how does this take away from ADHD <-> OCD comorbidity? However, it’s dismissible as a simple proposal. Then, after glossing over symptoms and the sort, he ends the video by talking about CDS (Cognitive Disengagement Syndrome). This is where things take an interesting turn, as we stray farther away from a scientifically sound conversation. He states “Finally one of the most confounding factors in research to date with regard to the overlap of ADHD with OCD is that to my knowledge no one has studied the other attention disorder in ADHD that attention disorder is what we now call Cognitive Disengagement Syndrome. Please see my lectures on my channel for this disorder" Confounding? “One of the most confounding factors”??? That is strong language for something that he goes on to state “NOBODY” has looked into (see next quote). CDS is NOT recognized by the DSM (Diagnostic and Statistical Manual of Mental Disorders), and in no literature is presented as a factor that diminishes the ADHD <-> OCD comorbidity. “As you know it involves being more internally preoccupied with your attention whereas ADHD is being more externally attentive and preoccupied so very different. ADHD being more of an externally governed disorder and Cognitive Disengagement Syndrome being more of an internally preoccupied disorder, makes sense then that CDS might be a much more common attention disorder in OCD but nobody's looked" First, that is false. A 2023 study (published April 2023, over a year before Barkley’s November 2024 video) looked into CDS in children with OCD compared to controls. 21.3% of children with OCD had elevated CDS symptoms, while only 7.6% of controls did. CDS and OCD correlate positively, but it’s important to note that within the OCD group, those with elevated CDS had higher rates of ADHD comorbidity (61.5% vs 8.3%). Funnily, or not, these findings don’t support his hypothesis. CDS isn’t replacing ADHD here. Matter of fact, these two diagnoses are so characteristically different, that one would assume that the rate of misdiagnosis, if present, would be marginal at best. For reference, CDS is categorized by daydreaming, mental fogginess, lethargy, and “internal” preoccupation. In contrast, ADHD consists of distractibility (by external stimuli), forgetfulness, and attention sustenance issues. Now let’s look at this a layer deeper, what is it with Barkley and CDS? Barkley is currently the face of CDS (which we’ll refer to as SCT going forward, “Sluggish Cognitive Tempo”, renamed to CDS in 2022). He has received over $100k in speaking and consulting fees from Eli Lilly (big pharma co), which, totally unrelatedly, has a drug that could be used to treat SCT. Barkley made the Barkley Sluggish Cognitive Tempo Scale, alongside many others. Potential conflict of interest? Hmm… An unrelated honorable quote by Allen Frances, former DSM-IV task force chair, “Sluggish Cognitive Tempo' is a remarkably silly name for an even sillier proposal." Also, a disclaimer: I am not a medical professional, and there may be errors or oversimplifications in my interpretation of the research. Not medical advice, nothing more than an opinion piece. References: https://www.psychiatrictimes.com/view/no-child-left-undiagnosed (Allen Frances, MD) https://www.youtube.com/watch?v=i9rWfX1HYUA (Russell A. Barkley, Ph.D) https://www.researchgate.net/publication/370105801_Evaluation_of_cognitive_disengagement_syndrome_in_children_with_obsessive-compulsive_disorder_Clinical_implications (Turkish CDS Study) https://jamanetwork.com/journals/jamapsychiatry/fullarticle/2526239 (Meta-analysis)