Cognitive Disengagement Syndrome (CDS): Understanding the “Quiet Side” of Neurodiversity
When most people think of ADHD, what comes to mind is the restless, impulsive child who can’t sit still. But for many, ADHD — or ADHD-like issues — look very different. There is a quieter, slower, inward-facing experience that often flies under the radar. This is where the concept of Cognitive Disengagement Syndrome (CDS) comes in. Although not a formal diagnosis, CDS has gained growing attention from researchers and clinicians — including Russell A. Barkley, one of the leading experts in ADHD.
What Is Cognitive Disengagement Syndrome (CDS)?
CDS describes a pattern of sluggishness, daydreaming, mental fogginess and slowed behaviour or thinking. People with CDS often report feeling mentally “tuned out,” easily confused, or slow to get started and to process information. Commonly noted features include:
Frequent day-dreaming or appearing “spaced out”
Low alertness and feeling drowsy or lethargic
Slow movement or delayed responses
Difficulty staying engaged even in quiet, non-distracting settings
Trouble processing information quickly
While CDS and ADHD-Inattentive Presentation share some overlap — such as forgetfulness, distractibility and poor sustained attention — CDS is more about mental sluggishness than classic distractibility.
Barkley’s Perspective on CDS and ADHD
Russell Barkley’s research (2014, 2023) suggests that CDS represents a separate but frequently co-occurring condition with ADHD. He argues that CDS is not merely a subtype of ADHD-Inattentive, but rather a different cognitive profile that can exist with or without ADHD. In other words: someone may meet the criteria for ADHD-Inattentive and also show strong CDS-traits — or have CDS-traits without the impulsivity/self-regulation issues that mark ADHD. Barkley says that CDS reflects differences in attention-regulation and alertness (rather than inhibition/self-regulation, which are core deficits in ADHD). This may help explain why people with CDS tend to be quiet, slow, inwardly-focused — whereas people with ADHD-Combined or Hyperactive presentations tend to be energetic, restless, and outwardly impulsive.
CDS and Slow Processing Speed
A particularly interesting overlap is between CDS and slow processing speed, often measured in IQ or neuropsychological assessments. Many individuals with CDS-like traits show lower scores on Processing Speed Index (PSI) subtests (for example, Coding or Symbol Search on the WAIS) even when overall IQ is average or above. This doesn’t mean they’re less intelligent — rather that their brain takes longer to process visual or verbal information. This slower “cognitive tempo” can impact:
Academic performance (especially in timed tasks)
Work efficiency and task completion
Verbal fluency and response speed
Everyday decision-making and motivation
Importantly, processing speed and attention are distinct but related domains. Slow processing does not automatically equal ADHD, but in people with inattentive ADHD it may exacerbate the sense of “mental slowness” or fatigue.
Why CDS Isn’t a Formal Diagnosis
Despite decades of research, CDS remains a research construct rather than an official diagnosis in the DSM-5. There are still ongoing debates about whether it represents a distinct disorder, a subtype of ADHD, or even a dimension of internalising problems (e.g., anxiety, depression). Importantly for clinicians, recognising CDS is not about pathologising “slowness” — it’s about understanding cognitive diversity and tailoring support accordingly.
Recent Research Updates & Clinical Implications
Several newer studies shed additional light on CDS, helping to refine how we conceptualise and support it:
A 2025 study by Knouse & Becker found that in adults, CDS symptoms showed unique associations with poor sleep quality, longer sleep onset latency, greater daytime dysfunction and a preference for eveningness (i.e., being a “night-owl”), independent of ADHD symptoms.
A Spanish study of children (Cano-Crespo et al., 2023) found that higher CDS scores predicted internalising symptoms (e.g., depression, anxiety) as well as inattention, and that children with both CDS and ADHD had the highest prevalence of sleep problems.
A systematic review (Fredrick, Jacobson, Peterson & Becker, 2024) found that youth with chronic medical conditions often showed elevated CDS symptoms — and that CDS appears particularly linked to psychosocial functioning (peer relations, self-management) rather than always clear neuropsychological or academic impairments.
From a clinical or applied perspective (which you may find relevant given your work), these findings suggest that:
Sleep and circadian rhythm may be important correlates of CDS and should be assessed.
CDS might present with more internalising features (quiet withdrawal, lethargy) than classic ADHD, so screening instruments/observations need to go beyond overt hyperactivity.
Standard stimulant treatments used for ADHD may be less effective (or have different effects) in cases where CDS-traits predominate, so alternative or adjunctive strategies may be needed (see below).
Providing extra processing time, reducing time-pressure, adjusting task demands, or using external cues/stimulation (movement, background sound) may help individuals with CDS-type profiles.
Supporting People with CDS-Like Profiles
If you or someone you work with seems to fit this slower, more inward ADHD/CDS profile, here are some practical strategies:
Allow extra time for processing and responses (both in formal assessments and everyday tasks)
Reduce time-pressure where possible (in academic tasks, work tasks)
Use structured routines and external aids to minimise cognitive load (checklists, prompts, visual schedules)
Encourage external stimulation (mild movement, background ambient sound/music) to boost alertness and counter lethargy
Consider non-stimulant treatments, or alternative approaches, especially if stimulants worsen fatigue, anxiety or have limited effect
Address sleep hygiene and circadian factors — ensuring good sleep quality, regular wake/sleep routine, reducing evening exposure to screens, etc
Foster self-awareness: helping clients/individuals recognise that their “slowness” is not laziness, but a cognitive tempo difference — which in turn can reduce shame and help with self-advocacy
In Summary
Cognitive Disengagement Syndrome (CDS) is not yet a formal diagnosis, but it offers a valuable framework for understanding why some people with ADHD-Inattentive-type presentation experience mental fog, slow thinking and lethargy rather than classic distractibility or hyperactivity. Barkley’s work (and others’) highlights that this slower cognitive profile may stem from differences in brain networks linked to alertness and processing speed, not just inhibition/self-regulation. By acknowledging CDS, clinicians (and individuals) can better differentiate and support cases that don’t fit the typical ADHD picture — those whose minds may wander not out of distraction but because their cognitive tempo simply runs at a different pace.
References
Barkley, R. A. (2014). Attention-Deficit Hyperactivity Disorder: A Handbook for Diagnosis and Treatment (4th ed.). Guilford Press.
Barkley, R. A. (2023). Sluggish Cognitive Tempo: Current Status, Future Directions, and Clinical Implications. Journal of Attention Disorders.
Becker, S. P., Marshall, S. A., & McBurnett, K. (2014). Sluggish Cognitive Tempo in Abnormal Psychology: An Update and Review. Clinical Psychology Review, 34(3), 229–239.
Knouse, L. E. & Becker, S. P. (2025). Unique associations of ADHD and cognitive disengagement syndrome symptoms with sleep problems and circadian preference in adults. Sleep Medicine. (PubMed)
Cano-Crespo, A., Moreno-García, I., Servera, M., & Morales-Ortiz, M. (2023). Cognitive Disengagement Syndrome and Child Sleep Problems in ADHD, Anxiety and Depression. Healthcare, 11(14), 2022. (MDPI)
Fredrick, J. W., Jacobson, L. A., Peterson, R. K., & Becker, S. P. (2024). Cognitive Disengagement Syndrome (Sluggish Cognitive Tempo) and medical conditions: a systematic review and call for future research. Child Neuropsychology, 30(5), 783–817. (Johns Hopkins University)