Cognitive disengagement syndrome (CDS) is a syndrome characterized by developmentally inappropriate, impairing, and persistent levels of decoupled attentional processing from the ongoing external context and resultant hypoactivity. Symptoms often manifest in difficulties with staring, mind blanking, absent-mindedness, mental confusion, and maladaptive mind-wandering alongside delayed, sedentary, or slow motor movements. To scientists in the field, it has reached the threshold of evidence and recognition as a distinct syndrome.
Since 1798, the medical literature on attentional disorders has distinguished between at least two kinds: one a disorder of distractibility, lack of sustained attention, and poor inhibition (that is now known as ADHD), and the other a disorder of low power, arousal, or oriented/selective attention (now known as CDS). 'Mind in general' by Sir Alexander Crichton (hal.science)
Although inattention is implicated in both conditions, CDS is distinct from ADHD. Unlike ADHD, which is the result of deficient executive functioning and self-regulation, CDS presents with problems in arousal, maladaptive daydreaming, and oriented or selective attention (distinguishing what is important from unimportant in information that has to be processed rapidly), as opposed to poor persistence or sustained attention, inhibition, and executive functioning more generally. In educational settings, CDS tends to result in decreased work accuracy, while ADHD impairs productivity.
CDS can also occur as a comorbidity with ADHD in some people, leading to substantially higher impairment than when either condition occurs alone.
In contemporary science today, it is clear that this set of symptoms is important because it is associated with unique impairments, above and beyond ADHD. CDS independently has a negative impact on functioning (such as a diminished quality of life, increased stress, and suicidal behavior, as well as lower educational attainment and socioeconomic status). CDS is clinically relevant as multiple randomized controlled clinical trials (RCTs) have shown that it responds poorly to methylphenidate.
Originally, CDS was thought to represent about one in three persons with the inattentive presentation of ADHD, as a psychiatric misdiagnosis, and to be incompatible with hyperactivity. Subsequent research established that it can be comorbid with ADHD—and present in individuals without ADHD as well. Therefore, and due to many other lines of evidence, there is a scientific consensus that the condition is a distinct syndrome.
If CDS and ADHD coexist together, the problems are additive: those with both conditions had higher levels of impairment and inattention than adults with ADHD only and were more likely to be unmarried, out of work, or claiming disability benefits. CDS alone is also present in the population and can be significantly impairing in educational and occupational settings, even if it is not as pervasively impairing as ADHD. The studies on medical treatments are limited. However, research suggests that atomoxetine and lisdexamfetamine effectively reduce its symptoms and thus may be used to treat CDS.
The condition was previously called sluggish cognitive tempo (SCT). The terms concentration deficit disorder (CDD) or cognitive disengagement syndrome (CDS) have recently been preferred to SCT because they better and more accurately explain the condition and thus eliminate confusion.
Signs and symptoms CDS symptoms (Preliminary research criteria) Prone to daydreaming Easily confused or mentally foggy Spacey or inattentive to surroundings Mind seems to be elsewhere Stares blankly into space Underactive, slow moving or sluggish Lethargic or less energetic Trouble staying awake or alert Has drowsy or sleepy appearance Gets lost in own thoughts Apathetic or withdrawn, less engaged in activities Loses train of thought or cognitive set Processes information less quickly or accurately
Social behavior In many ways, those who have a CDS profile have some of the opposite symptoms of those with predominantly hyperactive-impulsive or combined presentation of ADHD: instead of being hyperactive, extroverted, obtrusive, excessively energetic, and risk takers, those with CDS are drifting, absent-minded, listless, introspective, and daydreamy. They feel like they are "in the fog" and seem "out of it".Russel A. Barkley (2013): Two Types of Attention Disorders Now Recognized by Clinical Scientists. In: Taking Charge of ADHD: The Complete, Authoritative Guide for Parents. Guilford Press (3rd ed.), p.150. .
The comorbid psychiatric problems often associated with CDS are more often of the internalizing types, such as anxiety, unhappiness, or depression. Most consistent across studies was a pattern of reticence and social withdrawal in interactions with peers. Their typically shy nature and slow response time has often been misinterpreted as aloofness or disinterest by others. In social group interactions, those with CDS may be ignored and neglected. People with classic ADHD are more likely to be rejected in these situations because of their social intrusiveness or aggressive behavior. Compared to children with CDS, they are also much more likely to show antisocial behaviors like substance abuse, oppositional-defiant disorder, or conduct disorder (frequent lying, stealing, fighting etc.). Fittingly, in terms of personality, ADHD seems to be associated with sensitivity to reward and fun seeking while CDS may be associated with punishment sensitivity.
Attention deficits Individuals with CDS symptoms may show a qualitatively different kind of attention deficit that is more typical of a true information processing problem; such as poor focusing of attention on details or the capacity to distinguish important from unimportant information rapidly. In contrast, people with ADHD have more difficulties with persistence of attention and action toward goals coupled with impaired resistance to responding to distractions. Unlike CDS, those with classic ADHD have problems with inhibition but have no difficulty selecting and filtering sensory input.
Some think that CDS and ADHD produce different kinds of inattention: While those with ADHD can engage their attention but fail to sustain it over time, people with CDS seem to have difficulty with engaging their attention to a specific task. Accordingly, the ability to orient attention has been found to be abnormal in CDS.
Both disorders interfere significantly with academic performance but may do so by different means. CDS may be more problematic with the accuracy of the work a child does in school and lead to making more errors. Conversely, ADHD may more adversely affect productivity that represents the amount of work done in a particular time interval. Children with CDS seem to have more difficulty with consistently remembering things that were previously learned and make more mistakes on memory retrieval tests than do children with ADHD. They have been found to perform much worse on psychological tests involving perceptual-motor speed or hand-eye coordination and speed. They also have a more disorganized thought process, a greater degree of sloppiness, and lose things more easily. The risk for additional learning disabilities seems equal in both ADHD and CDS (23–50%), but math disorders may be more frequent in the CDS group.
A key behavioral characteristic of those with CDS symptoms is that they are more likely to appear to be lacking motivation and may even have an unusually higher frequency of daytime sleepiness. They seem to lack energy to deal with mundane tasks and will consequently seek to concentrate on things that are mentally stimulating perhaps because of their underaroused state. Alternatively, CDS may involve a pathological form of excessive mind-wandering.
Executive function The executive system of the human brain provides for the cross-temporal organization of behavior toward goals and the future and coordinates actions and strategies for everyday goal-directed tasks. Essentially, this system permits humans to self-regulate their behavior so as to sustain action and problem solving toward goals specifically and the future more generally. Dysexecutive syndrome is defined as a "cluster of impairments generally associated with damage to the frontal lobes of the brain" which includes "difficulties with high-level tasks such as planning, organising, initiating, monitoring, and adapting behaviour". Such executive deficits pose serious problems for a person's ability to engage in self-regulation over time to attain their goals and anticipate and prepare for the future.
Adele Diamond postulated that the core cognitive deficit of those with ADHD-I is working memory, or, as she coined in a paper on the subject, "childhood-onset dysexecutive syndrome". However, two more recent studies by Barkley found that while children and adults with CDS had some deficits in executive functions (EF) in everyday life activities, they were primarily of far less magnitude and largely centered around problems with self-organization and problem-solving. Even then, analyses showed that most of the difficulties with executive function deficits were the result of overlapping ADHD symptoms that may co-exist with CDS rather than being attributable to CDS itself. More research on the link of CDS to executive function deficits is clearly indicated, but—as of this time—CDS does not seem to be as strongly associated with executive function deficits as is ADHD.
Causes Unlike ADHD, the general causes of CDS symptoms are almost unknown, though one recent study of twins suggested that the condition appears to be nearly as heritable or genetically influenced in nature as ADHD.
Little is known about the neurobiology of CDS. However, symptoms of CDS seem to indicate that the posterior attention networks may be more involved here than the prefrontal cortex region of the brain and difficulties with working memory so prominent in ADHD. This hypothesis gained greater support following a 2015 neuroimaging study comparing ADHD inattentive symptoms and CDS symptoms in adolescents: It found that CDS was associated with a decreased activity in the left superior parietal lobule (SPL), whereas inattentive symptoms were associated with other differences in activation. A 2018 study showed an association between CDS and specific parts of the frontal lobes, differing from classical ADHD neuro-anatomy.
A study showed a small link between thyroid functioning and CDS symptoms suggesting that thyroid dysfunction is not the cause of CDS. High rates of CDS were observed in children who had prenatal alcohol exposure and in survivors of acute lymphoblastic leukemia, where they were associated with cognitive late effects.
Diagnosis CDS is included, with its previous name of sluggish cognitive tempo, as a diagnostic descriptor in the current International Classification of Diseases (ICD) released in 2022 under the World Health Organization (WHO). However, it is not included as a separate disorder in the ICD or current Diagnostic and Statistical Manual of Mental Disorders (DSM) (2013)Naguy A. Sluggish cognitive tempo and ADHD: la même chose? Prim Care Companion CNS Disord. 2022;24(1):20br02896. https://doi.org/10.4088/PCC.20br02896Gomez, R., Chen, W., & Houghton, S. (2023). Differences between DSM-5-TR and ICD-11 revisions of attention deficit/hyperactivity disorder: A commentary on implications and opportunities. World journal of psychiatry, 13(5), 138–143. https://doi.org/10.5498/wjp.v13.i5.138 although it may be in subsequent editions; to scientists in the field, it has reached the threshold of evidence and recognition as a distinct syndrome and is diagnosed by some professional practices. Screening tools have been created to assess CDS symptoms. Although some symptoms of other conditions are partially shared with CDS, they are distinct conditions.
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