Cognitive disengagement syndrome

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 inattentive presentation of ADHD,^[16] as a psychiatric misdiagnosis, and to be incompatible with hyperactivity. New studies found that it can be comorbid with ADHD – and present in individuals without ADHD as well. Therefore, some psychologists and psychiatrists view it as a separate mental disorder. Others dismiss it altogether or believe it is a distinct symptom group within ADHD (like Hyperactivity, Impulsivity or Inattention). It even may be useful as an overarching concept that cuts across different psychiatric disorders (much like emotional dysregulation, for example).^[17]


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]

Treatment[edit]

Treatment of CDS has not been well investigated. Initial drug studies were done only with the ADHD medication methylphenidate, and even then only with children who were diagnosed as ADD without hyperactivity (using DSM-III criteria) and not specifically for CDS. The research seems to have found that most children with ADD (attention deficit disorder) with Hyperactivity (currently ADHD combined presentation) responded well at medium-to-high doses.^[38] However, a sizable percentage of children with ADD without hyperactivity (currently ADHD inattentive presentation, therefore the results may apply to CDS) did not gain much benefit from methylphenidate, and when they did benefit, it was at a much lower dose.^[50]


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, The New York Times reported that sluggish cognitive tempo is the subject of pharmaceutical company clinical drug trials, including ones by Eli Lilly that proposed that one of its biggest-selling drugs, Strattera, could be prescribed to treat proposed symptoms of sluggish cognitive tempo.^[57] Other researchers believe that there is no effective treatment for CDS.^[58]

Epidemiology[edit]

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]