Cognitive disengagement syndrome
Cognitive disengagement syndrome | |
---|---|
Other names | Sluggish cognitive tempo (outdated) |
ADHD | |
Management | Medication, accommodations |
Medication | Atomoxetine |
Frequency | 5.1% (hypothesized[1]) |
Cognitive disengagement syndrome (CDS) is an attention syndrome characterised by prominent dreaminess, mental fogginess, hypoactivity, sluggishness, slow reaction time, staring frequently, inconsistent alertness, and a slow working speed. To scientists in the field, it has reached the threshold of evidence and recognition as a distinct syndrome.[2]
Since 1798, the medical literature on disorders of attention 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).[3]
Although it implicates attention, CDS is distinct from ADHD. Unlike ADHD, which is the result of deficient executive functioning and self-regulation,[4][5][6] 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 self-regulation.[7] In educational settings, CDS tends to result in decreased work accuracy, while ADHD impairs productivity.[8]
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,[9] increased stress and suicidal behaviour,[10] as well as lower educational attainment and socioeconomic status[11]). CDS is clinically relevant as multiple randomised controlled clinical trials (RCTs) have shown that it responds poorly to methylphenidate.[12][13][14][15]
Originally, CDS was thought to represent about one in three persons with the
If CDS and ADHD coexist together, the problems are additive: Those with both (ADHD + CDS) had higher levels of impairment and inattention than adults with ADHD only,[18] and were more likely to be unmarried, out of work or on disability.[19] CDS alone is also present in the population and can be quite 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[20][21][22][23] and lisdexamfetamine[20][24] 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.[19][25]
Signs and symptoms
ADHD (DSM-5) | |
---|---|
Inattention symptoms | Hyperactivity–impulsivity symptoms |
|
|
The symptoms must also
- be age-inappropriate,
- start before age 12,
- occur often and be present in at least two settings,
- clearly interfere with social, school, or work functioning,
- and not be better explained by another mental disorder.
Based on the above symptoms, three types of ADHD are defined:
- a predominantly inattentive presentation (ADHD-I)
- a predominantly hyperactive-impulsive presentation (ADHD-HI)
- a combined presentation (ADHD-C)
The predominantly inattentive presentation (ADHD-I) is restricted to the official inattention symptoms (see table above) and only to those. They capture problems with persistence, distractibility and disorganization. However, it fails to include these other, qualitatively different attention symptoms:[28][29][11]
CDS symptoms (preliminary research criteria) | ||
---|---|---|
|
As a comparison of both tables shows, there is no overlap between the official ADHD inattention symptoms and the CDS symptoms. That means that both symptom clusters do not refer to the same attention problems. They may exist in parallel within the same person but do also occur alone. However, one problem is still that some individuals who actually have CDS are currently misdiagnosed with the inattentive presentation.[11]
Social behaviour
In many ways, those who have a CDS profile have some of the opposite symptoms of those with
The
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
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.[33][34] Accordingly, the ability to orient attention has been found to be abnormal in CDS.[35]
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 which 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
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.[36] 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.[19]
Executive function
The
Adele Diamond postulated that the core cognitive deficit of those with ADHD-I is working memory, or, as she coined in her recent paper on the subject, "childhood-onset dysexecutive syndrome".[38] 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 EF 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 EF deficits is clearly indicated—but, as of this time, CDS does not seem to be as strongly associated with EF deficits as is ADHD.[19]
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.[39] That is to say that the majority of differences among individuals in these traits in the population may be due mostly to variation in their genes.[citation needed] The heritability of CDS symptoms in that study was only slightly lower than that for ADHD symptoms with a somewhat greater share of trait variation being due to unique environmental events. For instance, in ADHD, the genetic contribution to individual differences in ADHD traits typically averages between 75 and 80% and may even be as high as 90%+ in some studies. That for CDS maybe 50–60%.[citation needed]
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.[40] A 2018 study showed an association between CDS and specific parts of the frontal lobes, differing from classical ADHD neuroanatomy.[41]
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.[42][43][44]
Diagnosis
Cognitive disengagement syndrome is not included as a diagnosis in the current
Treatment
Treatment of CDS has not been well investigated. Initial drug studies were done only with the ADHD medication
However, one study and a retrospective analysis of medical histories found that the presence or absence of CDS symptoms made no difference in response to methylphenidate in children with ADHD-I.[51][19] These studies did not specifically and explicitly examine the effect of the drug on CDS symptoms in children. Atomoxetine may be used to treat CDS,[20] as multiple randomised controlled clinical trials (RCTs) have found that it is an effective treatment.[20][21][23] In contrast, multiple other RCTs have shown that it responds poorly to methylphenidate.[52][53][54][55]
Only one study has investigated the use of behavior modification methods at home and school for children with predominantly CDS symptoms and it found good success.[56]
In April 2014,
Prognosis
The
However, unlike ADHD, there are no longitudinal studies of children with CDS that can shed light on the developmental course and adolescent or adult outcomes of these individuals.
Epidemiology
Recent studies indicate that the symptoms of CDS in children form two dimensions: daydreamy-spacey and sluggish-lethargic, and that the former are more distinctive of the disorder from ADHD than the latter.[59][60] This same pattern was recently found in the first study of adults with CDS by Barkley and also in more recent studies of college students.[19] These studies indicated that CDS is probably not a subtype of ADHD but a distinct disorder from it. Yet it is one that overlaps with ADHD in 30–50% of cases of each disorder, suggesting a pattern of comorbidity between two related disorders rather than subtypes of the same disorder. Nevertheless, CDS is strongly correlated with ADHD inattentive and combined subtypes.[59][61] According to a Norwegian study, "[CDS] correlated significantly with inattentiveness, regardless of the subtype of ADHD."[62]
History
Early observations
There have been descriptions in literature for centuries of children who are very inattentive and prone to foggy thought.
Symptoms similar to
One example from fictional literature is Heinrich Hoffmann's character of "Johnny Head-in-Air" (Hanns Guck-in-die-Luft), in Struwwelpeter (1845). (Some researchers see several characters in this book as showing signs of child psychiatric disorders).[64]
The Canadian pediatrician Guy Falardeau, besides working with hyperactive children, also wrote about very dreamy, quiet and well-behaved children that he encountered in his practice.[65]
First research efforts
In more modern times, research surrounding attention disorders has traditionally focused on hyperactive symptoms, but began to newly address inattentive symptoms in the 1970s. Influenced by this research, the
In the 1990s, Weinberg and Brumback proposed a new disorder: "primary disorder of vigilance" (PVD). Characteristic symptoms of it were difficulty sustaining alertness and arousal, daydreaming, difficulty focusing attention, losing one's place in activities and conversation, slow completion of tasks and a kind personality. The most detailed case report in their article looks like a prototypical representation of CDS. The authors acknowledged an overlap of PVD and ADHD but argued in favor of considering PVD to be distinct in its unique cognitive impairments.[67][68] Problematic with the paper is that it dismissed ADHD as a nonexistent disorder (despite it having several thousand research studies by then) and preferred the term PVD for this CDS-like symptom complex. A further difficulty with the PVD diagnosis is that not only is it based merely on 6 cases instead of the far larger samples of CDS children used in other studies but the very term implies that science has established the underlying cognitive deficits giving rise to CDS symptoms, and this is hardly the case.[19]
With the publication of
Prior to 2001, there were a total of four scientific journal articles specifically addressing symptoms of CDS. But then a researcher suggested that sluggish tempo symptoms (such as inconsistent alertness and orientation) were, in fact, adequate for the diagnosis of ADHD-I. Thus, he argued, their exclusion from DSM-IV was inappropriate.[69] The research article and its accompanying commentary urging the undertaking of more research on CDS spurred the publication of over 30 scientific journal articles to date which specifically address symptoms of CDS.[17]
However, with the publication of DSM-5 in 2013, ADHD continues to be classified as predominantly inattentive, predominantly hyperactive-impulsive, and combined type and there continues to be no mention of CDS as a diagnosis or a diagnosis subtype anywhere in the manual. The diagnosis of "ADHD, not otherwise specified" also no longer includes any mention of CDS symptoms.[26] Similarly, ICD-10, the medical diagnostic manual, has no diagnosis code for CDS. Although CDS is not recognized as a disorder at this point, researchers continue to debate its usefulness as a construct and its implications for further attention disorder research.[17]
Controversy
Significant skepticism has been raised within the medical and scientific communities as to whether CDS, currently considered a "symptom cluster," actually exists as a distinct disorder.[57]
Adding to the controversy are potential conflicts of interest among the condition's proponents, including the funding of prominent CDS researchers' work by the global pharmaceutical company Eli Lilly.[57] When referring to the "increasing clinical referrals occurring now and more rapidly in the near future driven by increased awareness of the general public in [CDS]", Dr. Barkley writes: "The fact that [CDS] is not recognized as yet in any official taxonomy of psychiatric disorders will not alter this circumstance given the growing presence of information on [CDS] at various widely visited internet sites such as YouTube and Wikipedia, among others."[70]
See also
- Attention deficit hyperactivity disorder controversies
- Bradyphrenia (slowness of thought)
- Clouding of consciousness
- Cognitive Tempo
- Sluggish schizophrenia
- Type B personality
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External links
- ADHD in Adults: Sluggish cognitive tempo and ADHD