Rethinking
cognitive
disengagement
syndrome (CDS)
in ADHD and
ASD — and why
children learn to
disengage, and
keep doing it

Large new study finds cognitive fog belongs more to autism and depression than to ADHD

Cognitive disengagement syndrome (CDS) is the recently renamed construct that spent decades being called sluggish cognitive tempo. The terminology changed by consensus in 2023, but the cluster it points at is older than the name: daydreaming, blank staring, mental fogginess, slowed or underactive behaviour, the sense of a mind drifting somewhere just out of reach of the task in front of it. For most of its research history, this cluster was treated as a feature of ADHD — specifically of the inattentive presentation, where it seemed to sit naturally alongside distractibility and difficulty sustaining focus (remember: “attention” is most typically researched in the west as a task-mediating-externally-coupled-mechanism; aka cybernetic attention, not human attention). A study published in European Child & Adolescent Psychiatry in 2026 by Boccaccio and colleagues, with the Nijmegen-based ADHD and autism researcher Jan Buitelaar as senior author, suggests that filing was a mistake.

The researchers examined 958 clinically referred children and adolescents — 353 with ADHD, 494 with autism, 111 with internalising disorders such as anxiety and depression — and compared CDS levels across the three groups using items drawn from the Child Behavior Checklist. The historical assumption would predict that the ADHD group, carrying the inattentive presentation CDS was supposedly part of, would show the highest levels. They did not.

The autism and internalising groups showed higher cognitive disengagement than the ADHD group, and the pattern held in a subsample with no comorbidity and after controlling for sex and age. When the researchers looked at what cognitive disengagement syndrome actually correlated with, it tracked more closely to autistic traits and to affective symptoms than to either ADHD inattention or hyperactivity.

Two further findings sharpen the picture, and one of them matters more than it first appears. Higher CDS predicted lower quality of life across every diagnostic group, independent of which diagnosis a child carried — the fog is genuinely costly wherever it appears. And CDS was not associated with how many comorbid conditions a child had, which means it is not simply a marker of being more unwell in general. It is its own thing, cutting across diagnostic lines, sitting closest to the autistic and the internalising poles rather than to the attentional one it was named beside.

A necessary caution about the measurement, because I do not want to oversell findings. The CDS construct here rests on a small number of checklist items rated by parents, with an internal consistency that is weak by conventional standards, in a cross-sectional design that cannot establish what causes what. The authors are candid about this and, therefore, so am I. The construct is also genuinely contested within the field — it remains undecided whether CDS is an independent condition, a transdiagnostic dimension, or a specifier attached to other diagnoses. None of that invalidates the central observation, which replicates a direction other recent work has been moving in. But it means the right register here is “the evidence points this way,” not “the matter is settled.”

The “shared inattention” that supposedly links autism and ADHD may be two different things wearing one label

For years, the high rate of co-occurrence between autism and ADHD has been partly explained by what looks like a shared symptom: inattention. Both groups, the reasoning goes, struggle to attend, so inattention is the common thread, the overlapping territory where the two conditions meet. The Boccaccio findings invite a more uncomfortable and more interesting reading. The “inattention” observed in autistic children and the inattention observed in ADHD may not be the same process at all. They may be two distinct things that happen to be scored by the same items on the same checklists and therefore counted as one.

ADHD inattention, mechanistically, is built around distractibility and a failure of inhibition. The attention is captured, pulled outward, fragmented by competing stimuli; the difficulty is in filtering and holding. What gets coded as inattention in an autistic child may be something quite different — disengagement, withdrawal, a turning-inward, difficulty responding to socially complex demands, the mind pulling away from an environment rather than being scattered across it.

One is attention captured and fragmented. The other is attention withdrawn and damped down. They produce similar-looking behaviour at the desk/workspace — a child not visibly attending to the task required of them — and the diagnostic instruments, sorting by surface appearance, file both under the same heading and then attribute the heading to whichever disorder the child already carries.

This is the lens-level problem I keep documenting, appearing here in the structure of a checklist. A behaviour is observed, sorted by how it looks rather than by what is generating it, and assigned to a category on the basis of the label already in the file. The fog gets called ADHD-inattention in a child diagnosed with ADHD and something else in a child diagnosed with autism, when the more parsimonious reading — the one the correlational data here actually support — is that disengagement is a single cross-cutting process that clusters with the autistic and affective dimensions and has been wrongly housed inside ADHD for thirty years because that is where the field happened to be looking.

If that reading holds, then a portion of the autism-ADHD overlap that has been explained as shared inattention dissolves. What looked like common ground turns out to be a labelling artefact: two different internal situations producing one externally similar behaviour, collapsed into a single measured symptom. The conditions still co-occur, but the bridge between them is not the one the field assumed it was standing on.

Why a developing nervous system learns to disengage — and keeps choosing it

Here is the question the study measures around but never asks: why would a child’s neurology learn to disengage, and then keep choosing disengagement over engagement? The framing of CDS as a syndrome treats the fog as something a child has — a deficit, an underactivity, a tempo that runs slow. But disengagement is not the absence of a capacity. It is an action. A child who goes foggy, who stares through the task, who slows down and drifts inward, is doing something. The more useful question is what that something is for.

Consider that the construct clusters most tightly with the autistic and the internalising poles — exactly the populations for whom the surrounding environment is most likely to be chronically over-demanding. The autistic child in a sensory and social setting calibrated for someone else; the anxious or depressed child managing a continuous internal load the environment does not see or accommodate. For both, sustained outward engagement is expensive in a way it is not for the typically-developing child the classroom and the clinic were designed around. Disengagement, in that light, stops looking like a failure to engage and starts looking like a learned withdrawal from demands that exceed what can be safely or sustainably met — with compliance. The mind turns inward and damps down because turning outward and staying there costs too much.

And a nervous system keeps choosing what works. Disengagement gets reinforced for the same reason any adaptive response gets reinforced: in the short term, it reduces load. It lowers the unbearable intensity of an over-demanding environment to something survivable. A regulatory move that succeeds at reducing strain is a regulatory move the developing brain will reach for again, and again, until it stops being an occasional response and becomes a settled trait — a default.

This is the internalisation the diagnostic frame cannot see, because the frame measures the endpoint (a foggy, disengaged child) and skips the history that produced it (an environment that taught a developing nervous system that engaging cost more than withdrawing). What gets scored on the checklist as a slow cognitive tempo may be the accumulated residue of years of a child’s neurology learning, correctly, that disengaging was the more effective option.

This is the same shape I’ve traced before in adjacent territory. The masking work described how sustained interface labour produces an alexithymia-like flattening downstream — not a trait a person was born with, but the internalised cost of managing an environment not built for them. The affect-labelling piece located reduced access to internal states downstream of chronic suppression rather than as a standalone deficit. Cognitive disengagement may be what that process looks like from the outside in childhood: attention turned inward and quietened, not because the attentional machinery is faulty, but because the developing system learned that outward engagement was not safe to sustain. The fog is not the lack of a signal. The fog is the signal — the visible trace of a nervous system that adapted to conditions the diagnostic system never thought to examine.

What gets missed when a learned adaptation is filed as a new disorder

The field is currently deciding what to do with cognitive disengagement syndrome — whether to confirm it as an independent diagnostic entity, attach it as a specifier, or treat it as a transdiagnostic dimension. Whichever route wins, the default trajectory is the same: the cluster becomes a thing to be screened for, scored, and ultimately remediated, most likely through interventions aimed at the individual child who carries it. This is the well-worn path the moment a measurable cluster of behaviour acquires a name. And it repeats the pattern that the Directory’s editorial coverage exists to flag: a response to environmental conditions gets relocated inside the person, renamed as a deficit, and handed back to them as their problem to fix.

The quality-of-life finding has to be held carefully here, because it is the part most easily misused in either direction. These children do report lower wellbeing, and that is real — adaptive does not mean free, and a child who has learned to disengage is paying for it in diminished engagement with a life that might otherwise be richer. Disengagement that began as a sensible reduction of unbearable load can harden into a default that closes the child off from the very experiences that would help.

So the answer is not to wave the construct away as invented; the distress is genuine and the withdrawal does carry a cost. But the lowered quality of life is at least as consistent with the reading offered here as with the disorder framing. A child who has learned that engaging is not safe, and whose neurology has settled into withdrawal as a default, would be expected to report exactly this: a life lived at a remove, lower in engagement and lower in wellbeing, because the adaptation that protected them in the short term is expensive to sustain over years.

What the syndrome framing misses, then, is the question that should organise the entire response. Not “how do we treat the child’s disengagement,” but “what was the child disengaging from, and why did it become the better option for them.” A research programme that takes CDS seriously as a deficit to be remediated will produce individual-level interventions aimed at making foggy children attend — and will likely find, as the field has found across decades of similar efforts, that the gains evaporate the moment the child returns to the environment that produced the adaptation in the first place. A research programme that takes seriously what the disengagement is for asks a different set of questions: what made sustained engagement so costly for this child, what would have to change about the environment for engagement to become affordable again, and whether the withdrawal that looks like a syndrome is in fact an intelligent nervous system responding accurately to conditions that were never made safe.

The study is careful, the construct is real, and the lowered wellbeing it documents deserves to be taken seriously rather than explained away. The renaming from sluggish cognitive tempo to cognitive disengagement was itself an improvement — it at least names the disengagement as something happening rather than a vague slowness. The next move, the one the field has not yet made, is to stop asking only what the fog is and start asking what it is for. A child does not learn to disengage and keep disengaging for no reason. The reason is the part the checklist cannot measure, and it is the part that matters most.

Citations

Boccaccio, F. M., Klip, H., Vollebregt, M. A., Pieters, S., Rizzo, R., Pirrone, C., & Buitelaar, J. K. (2026) — Cognitive disengagement syndrome across attention deficit/hyperactivity disorder, autism spectrum disorder, and internalizing disorders: towards a transdiagnostic construct