Sluggish cognitive tempo
Sluggish cognitive tempo (SCT) is a cluster of symptoms, and possibly a distinct disorder, characterized by the individual being daydreamy, mentally foggy, easily confused, and staring frequently. Individuals also have symptoms of hypoactivity, lethargy, slow movement, and even sleepiness. Children with SCT appeared to have slow processing speed and reaction times. Compared to individuals with ADHD, children with SCT have far lower rates of comorbid oppositional defiant disorder and conduct disorder, a higher occurrence of anxiety symptoms, and possibly a greater occurrence of depression. Most consistent across studies was a pattern of social withdrawal in interactions with peers rather than the social intrusiveness, aggressiveness, and rejection so often evident in the more well-known attention disorder, ADHD. SCT is strongly correlated with ADHD inattentive and combined subtypes. However, SCT can be found in individuals who would not receive an ADHD diagnosis, and it can also be found in some individuals with ADHD hyperactivity/impulsivity. Efforts are currently underway to encourage researchers to use the less offensive term, Concentration Deficit Disorder, or CDD, for SCT. This would also be more accurate in that the actual underlying cognitive deficit(s) associated with SCT/CDD are not yet known and so should not be implied in its label.
Symptoms of the inattentive and combined forms of ADHD were first described in 1775 by Melchior Adam Weikard  and in 1798 by Alexander Crichton in their medical textbooks. Although Weikard mainly described a single disorder of attention resembling ADHD, Crichton discussed at least two disorders of attention. One resembled the symptoms of ADHD but the second referred to a low power of attention that led to lethargy, an inability to concentrate or focus attention properly, and inactivity. This second attention disorder may be the first reference to an SCT-like syndrome in the medical literature.
Originally, SCT was thought to be a subtype of ADHD, especially the Primarily Inattentive Type now known as a "Presentation" in DSM-5 (or ADHD-I). However, SCT is not recognized as a mental disorder in any of the medical or diagnostic manuals, such as the ICD-10 or the DSM-IV, or the more recent DSM-5 SCT continues to be the subject of increasing studies in the psychological literature, particularly that involving ADHD, and focuses on how this group of individuals may differ from or be similar to those having ADHD. For instance, the January 2014 issue of the Journal of Abnormal Child Psychology devotes an entire special section to recent research studies of SCT.
SCT was originally discovered in the 1980s when the DSM-III first began subtyping ADHD as attention deficit disorder (ADD) with or without hyperactivity. Research comparing these subtypes produced a mixed pattern of results with some studies supporting the distinction while others did not. Later studies comparing these subtypes began to notice that those with ADHD-I seemed to have a higher frequency of symptoms of daydreaming, staring, being spacey or easily confused, mental fogginess, and hypoactivity or lethargy. This pattern of symptoms was distinct from those of ADHD in studies statistically analyzing these symptom patterns and so was labelled SCT. The term itself is most likely to have originated with Ben Lahey, then at the University of Georgia, in one of his several studies on this symptom pattern. By the late 1990s and early 2000s, studies began to appear that specifically chose participants for having these symptoms of SCT directly rather than those who met criteria for ADHD-I. Such research proved to be more fruitful in identifying a more reliable pattern of differences in cognitive abilities, comorbid disorders and impairments than had been the case for ADHD-I.
In the 1990s, Weinberg and Brumback described six cases and proposed a new disorder: "primary disorder of vigilance" (PVD), which seems to be very similar to what is now called SCT. Typical symptoms of it included difficulty sustaining alertness and arousal, daydreaming, difficulty focusing attention, losing one's place in activities and conversation, slow/delayed/incomplete tasks and a specific temperament and personality type among other criteria. The most detailed case report in their scientific article looks like a prototypical representation of SCT. The authors acknowledged an overlap of PVD and ADHD but argued in favor of considering PVD to be distinct in its unique cognitive impairments. 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 SCT-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 SCT children used in other studies but the very term implies that science has established the underlying cognitive deficits giving rise to SCT symptoms, and this is hardly the case.
Recent studies indicate that the symptoms of SCT 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. This same pattern was recently found in the first study of adults with SCT by Barkley. This has also been the case with more recent studies of college students. These studies indicated that SCT 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.
In many ways, those who have an SCT profile have some of the opposite symptoms of those with classic ADHD: instead of being hyperactive, extroverted, obtrusive, and risk takers, those with SCT are drifting, introspective and daydreamy, and feel as if "in the fog". Due to their drifting tendencies, those with SCT may have trouble with memory retrieval. They also do not have the same risks for oppositional defiant disorder, conduct disorder, or social aggression, and thus may have different life course outcomes compared to children with ADHD who have far higher risks for these other "externalizing" disorders. A key behavioral characteristic of those with SCT 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. Those with SCT symptoms may show a qualitatively different kind of attention deficit that is more typical of a true information input-output problem, such as poor focusing of attention on important details, erratic memory retrieval and active working memory, and possibly excessive mind-wandering. Conversely, those with ADHD are characteristically excessively energetic and have no difficulty processing information.
Despite the apparent incompatibility between SCT and hyperactivity, and contrary to previous suggestions that SCT could distinguish a distinct group within the ADHD-PI type, Barkley's study found that SCT was comorbid with ADHD-C almost as often as with ADHD-PI. According to a Norwegian study, "SCT correlated significantly with inattentiveness, regardless of the subtype of ADHD."
Unlike ADHD, the general causes of SCT 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. 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. The heritability of SCT 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 SCT may be 50-60%. Far less is known about SCT yet the symptoms seem to indicate that the posterior attention networks may be more involved in the disorder than the prefrontal cortex region of the brain and difficulties with working memory so prominent in ADHD. Unlike ADHD in which there exist hundreds of studies on molecular genetics identifying candidate genes that may contribute to the disorder, there are no studies of molecular genetics that specifically evaluated individuals having SCT.
Although ADHD appears to be linked to problems with the availability of or sensitivity to variations dopamine and norepinephrine, and/or the efficiency of the large chemical structures of the specific receptors and re-uptake receptors, the neurotransmitters that may be linked to SCT are unknown.
A recent study found a link between thyroid functioning and SCT symptoms, but effects were small and suggests that thyroid dysfunction is not the cause of SCT. SCT symptoms were also observed in pediatric survivors of acute lymphoblastic leukemia, where they were associated with cognitive late effects. Another study found high rates of SCT in children who had suffered prenatal alcohol exposure. However, since as much as 5% of the population may have SCT, these causes may not account for the majority of cases.
Treatment of SCT has not been well investigated. Initial drug studies were done only with the ADHD medication, methylphenidate (Ritalin/Concerta), and even then only with children who were diagnosed as ADD without hyperactivity (DSM-III) and not specifically for SCT. The research seems to have found that most children with DSM-III ADD-H (currently ADHD-C) responded well at medium-to-high doses. However, a sizable percentage of children with ADD without hyperactivity (using DSM-III criteria; therefore the results may apply to SCT) did not gain much benefit from methylphenidate, and when they did benefit, it was at a much lower dose. One study found that the presence or absence of SCT symptoms made no difference in response to methylphenidate in children with ADHD-PI. Another study, a retrospective analysis of medical histories, also found that children with SCT responded well to methylphenidate. But these studies did not specifically examine the effect of the drug on SCT symptoms. The only study of medication to date to specifically evaluate drug effects on SCT symptoms in children used atomoxetine and found it to have significant beneficial effects.
Only one study has investigated the use of behavior modification methods at home and school for children with predominantly SCT symptoms and it found good success.
Some SCT individuals report anecdotally that they experience improvement in their ability to focus through meditation, but this claim has not been subjected to scientific study.
The prognosis of SCT is unknown. In contrast, much is known about the adolescent and adult outcomes of children having ADHD. Those with SCT symptoms typically show a later onset of their symptoms than do those with ADHD, perhaps by as much as a year or two later on average. They have as much or more difficulty with academic tasks and far fewer social difficulties than do people having ADHD (see population sample studies of SCT by Barkley, above). However, unlike ADHD, there are no longitudinal studies of children with SCT that can shed light on the developmental course and adolescent or adult outcomes of these individuals. Even so, the 2012 study by Barkley of adults noted above suggests that the disorder is present in the adult population and can be quite impairing in educational and occupational settings, even if it is not as pervasively impairing as ADHD in adults.
SCT is believed to possibly involve difficulties with selective attention or the capacity to distinguish important from unimportant information rapidly. Alternatively, as noted above, it may involve a pathological form of mind-wandering. In contrast, people with ADHD have more difficulties with persistence of attention and action toward goals coupled with impaired resistance to responding to distractions. Both disorders interfere significantly with academic performance but may do so by different means. SCT may be more problematic with the accuracy of the work a child does in school while ADHD may more adversely affect productivity, or the amount of work done in a particular time interval. Also, children with SCT may have difficulty with verbal retrieval from long term memory than children with ADHD. They also have a more disorganized thought process, a greater degree of sloppiness, and lose things more easily. They tend to have as high a risk for comorbid learning disabilities as do people with ADHD (23-50%). Yet there is some evidence that the type of learning disorders may differ in SCT, perhaps with a higher prevalence of math disorders than seen in those with ADHD. Instead of having greater difficulty selecting and filtering sensory input, as is in the case of SCT, people with ADHD have problems with inhibition. The comorbid psychiatric problems often associated with SCT are more often of the internalizing types, such as anxiety, depression, and social withdrawal. Their typically shy nature and slow response time has often been misinterpreted as aloofness or disinterest by others. In social group interactions, those with SCT may be ignored. Those with the other types of ADHD are more likely to be rejected in social situations, because of more intrusive or aggressive behavior. Those with classic ADHD also show externalizing problems such as substance abuse, oppositional-defiant disorder, and, to a lesser degree, conduct disorder. One recent investigation has also found differential associations to certain personality dimensions in children: ADHD was associated with sensitivity to reward while SCT symptoms were specifically associated with punishment sensitivity.
As the causes of SCT are largely unknown at this time, there is no known way to prevent SCT.
Relationship to dysexecutive syndrome
The executive system of the human brain provides for the cross-temporal organization of behavior towards goals and the future more generally 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."[dead link] 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-PI (ADD) and possibly SCT, is working memory, or, as she coined in her recent paper on the subject, "childhood-onset dysexecutive syndrome". She states:
- "Instructional methods that place heavy demands on working memory will disproportionately disadvantage individuals with ADD".
- "Language problems often co-occur with ADD, and it is suggested that part of the reason might be that linguistic tasks, especially verbal ones, tax working memory so heavily. Spatial, musical, and artistic skills, however, are often preserved or superior in individuals with ADD."
- "The working memory deficit in many children with ADD is accompanied by markedly slowed reaction times, a characteristic that covaries with poorer working memory in general."
- "Individuals with ADD have difficulty maintaining a sufficiently high level of motivation to complete a task...They go looking for something else to do or think about because they are bored...to remedy a general lower arousal level..."
However, two more recent studies by Barkley noted earlier found that while children and adults with SCT 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 SCT rather than being attributable to SCT itself. More research on the link of SCT to EF deficits is clearly indicated but as of this time, SCT does not seem to be as strongly associated with EF deficits as is ADHD.
- Depersonalization disorder
- Attention-deficit hyperactivity disorder
- ADHD predominantly inattentive
- Bipolar II disorder
- Kleine-Levin Syndrome
- Low arousal theory
- Type B Personality
- Barkley, R. A. (2014) Sluggish cognitive tempo (Concentration Deficit Disorder): Current status, future directions, and a plea to change the name. Journal of Abnormal Child Psychology, 42:117-125. DOI: 10.1007/s10802-013-9824-y
- Barkley, R. A. & Peters, H. (2012). The earliest reference to ADHD in the medical literature? Melchior Adam Weikard's description of "Attention Deficit" (Mangel der Aufmerksamkeit, Attentio Volubilis). Journal of Attention Disorders, 16, 623-630.DOI: 10.1177/1087054711432309
- Palmer, E. D., & Finger, S. (2001). An early description of ADHD (Inattentive Subtype): Dr. Alexander Crichton and "Mental Restlessness" (1798). Child Psychology and Psychiatry Review, 6, 66-73. doi:10.1111/1475-3588.00324
- American Psychiatric Association (2013). Diagnostic and Statistical Manual for Mental Disorders (5th edition). Washington, DC: American Psychiatric Association.
- Stephen P. Becker (2014): Sluggish Cognitive Tempo in Abnormal Child Psychology: An Historical Overview and Introduction to the Special Section. Journal of Abnormal Child Psychology, 42, p.1-6. DOI: 10.1007/s10802-013-9825-x
- Carlson, C. L. (1986). Attention deficit disorder with and without hyperactivity: A review of preliminary experimental evidence. In B. B. Lahey & A. E. Kazdin (Eds.), Advances in Clinical Child Psychology (Vol. 9, pp. 153-175). New York: Plenum.
- Milich R., Ballentine , Lynam D.R. (2001). "ADHD/combined type and ADHD/predominantly inattentive type are distinct and unrelated disorders". Clinical Psychology: Science and Practice 8 (4): 463–488. doi:10.1093/clipsy.8.4.463.
- Hartman C. A., Willcutt E. G., Rhee S. H., Pennington B. F. (2004). "The relation between sluggish cognitive tempo and DSM-IV ADHD". Journal of Abnormal Child Psychology 32 (5): 491–503. doi:10.1023/B:JACP.0000037779.85211.29. PMID 15500029.
- Garner A. A., Marceaux J. C., Mrug S., Patterson C., Hodgens B. (2010). "Dimensions and correlates of attention deficit/hyperactivity disorder and sluggish cognitive tempo". Journal of Abnormal Child Psychology 38 (8): 1097–1107. doi:10.1007/s10802-010-9436-8. PMC 3278310. PMID 20644992.
- McBurnett K., Pfiffner L. J., Frick P. J. (2001). "Symptom properties as a function of ADHD type: an argument for continued study of sluggish cognitive tempo". Journal of Abnormal Child Psychology 29 (3): 207–213. doi:10.1023/A:1010377530749. PMID 11411783.
- Wahlstedt C., Bohlin G. (2010). "DSM-IV defined inattention and sluggish cognitive tempo: independent and interactive relations to neuropsychological factors and comorbidity". Child Neuropsychology 16 (4): 250–365. doi:10.1080/09297041003671176.
- McBurnett, Keith; Pfiffner, Linda Jo (2007). Attention Deficit Hyperactivity Disorder - Concepts, Controversies, New Directions. In: Chapter 32, Sluggish Cognitive Tempo: The Promise and Problems of Measuring Syndromes in the Attention Spectrum, p. 352.
- Weinberg, Warren A.; Brumback, Roger A (1990). Primary disorder of vigilance: A novel explanation of inattentiveness, daydreaming, boredom, restlessness, and sleepiness. The Journal of Pediatrics, 116 (5), p. 720-725. doi: 10.1016/S0022-3476(05)82654-X
- Barkley, R. A. (2014). Concentration deficit disorder (sluggish cognitive tempo). In R. A. Barkley (Ed.), Attention deficit hyperactivity disorder: a handbook for diagnosis and treatment (4th ed.). New York: Guilford Press.
- Becker, S. P. (2013). Topical review: Sluggish Cognitive Tempo: Research Findings and Relevance for Pediatric Psychology. Journal of Pediatric Psychology. Advance online publication. doi: 10.1093/jpepsy/jst058
- Penny A. M., Waschbusch D. A., Klein R. M., Corkum P., Eskes G. (2009). "Developing a measure of sluggish cognitive tempo for children: Content validity, factor structure, and reliability". Psychological Assessment 21 (3): 380–389. doi:10.1037/a0016600. PMID 19719349.
- Barkley, R. A. (2011, May 23). Distinguishing Sluggish Cognitive Tempo From Attention-Deficit/Hyperactivity Disorder in Adults. Journal of Abnormal Psychology. Advance online publication. doi:10.1037/a0023961.
- Becker, S. P., Langberg, J. M., Luebbe, A. M., Dvorsky, M. R., & Flannery, A. J. (2013). Sluggish cognitive tempo is associated with academic functioning and internalizing syptoms in college students with and without attention-deficit/hyperactivity disorder. Journal of Clinical Psychology, Epub ahead of print. DOI: 10.1002/jclp.22046
- Becker, S. P., Luebbe, A. M., & Langberg, J. M. (in press). Attention-deficit/hyperactivity disorder dimensions and sluggish cognitive tempo symptoms in relation to college students' sleep functioning. Child Psychiatry and Human Development, in press.
- Adams, Z. W., Milich, R., & Fillmore, M. T. (2010). A case for the return of attention-deficit disorder in DSM-5. The ADHD Report,18(3), 1–6.
- Barkley, R. A. (2014), 4th revised edtition. Attention Deficit Hyperactivitv Disorder: A handbook for diagnosis and treatment
- Skirbekk, Benedicte; Hansen, Berit Hjelde; Oerbeck, Beate; Kristensen, Hanne (2011). "The Relationship Between Sluggish Cognitive Tempo, Subtypes of Attention-Deficit/Hyperactivity Disorder, and Anxiety Disorders". Journal of Abnormal Child Psychology 39 (4): 513–525. doi:10.1007/s10802-011-9488-4. ISSN 0091-0627.
- Moruzzi, S., Rijsdijk, F., & Battaglia, M. (2014). A twin study of the relationships among inattention, hyperactivity/impulsivity and sluggish cognitive tempo. Journal of Abnormal Child Psychology, 42, 63-75. DOI 10.1007/s10802-013-9725-0
- Becker, S. P., Luebbe, A. M., Greening, L., Fite, P. J., & Stoppelbein, L. (2012). A preliminary investigation of the relation between thyroid functioning and sluggish cognitive tempo in children. Journal of Attention Disorders. doi: 10.1177/1087054712466917
- Reeves, C. B., Palmer, S., Gross, A. M., Simonian, S. J., Taylor, L., Willingham, E., & Mulhern, R. K. (2007). Brief Report: Sluggish Cognitive Tempo Among Pediatric Survivors of Acute Lymphoblastic Leukemia" Journal of Pediatric Psychology 32(9), 1050–1054. doi:10.1093/jpepsy/jsm063
- Graham, D. M., Crocker, N., Deweese, B. N., Roesch, S. C., Coles, C. D., Kable, J. A., … Mattson, S. N. (2013). Prenatal Alcohol Exposure, Attention-Deficit/Hyperactivity Disorder, and Sluggish Cognitive Tempo. Alcoholism: Clinical & Experimental Research, 37, 338–346.
- Barkley, R. A. (2012). Distinguishing sluggish cognitive tempo from attention-deficit/hyperactivity disorder in adults" Journal of Abnormal Psychology 121(4), 978–990. doi:10.1037/a0023961
- Diamond A (2005). "Attention-deficit disorder (attention-deficit/ hyperactivity disorder without hyperactivity): a neurobiologically and behaviorally distinct disorder from attention-deficit/hyperactivity disorder (with hyperactivity)". Dev. Psychopathol. 17 (3): 807–25. doi:10.1017/S0954579405050388. PMC 1474811. PMID 16262993.
- Barkley, R. A., DuPaul, G. J., & McMurray, M. B. (1991). Attention deficit disorder with and without hyperactivity: clinical response to three dose levels of methylphenidate" Pediatrics 87(4), 519–531.
- Ludwig, H. T., Matte, B., Katz, B., & Rohde, L. A. (2009). Do Sluggish Cognitive Tempo Symptoms Predict Response to Methylphenidate in Patients with Attention-Deficit/Hyperactivity Disorder–Inattentive Type? Journal of Child & Adolescent Psychopharmacology, 19(4), 461–465.
- Viola, L., Ruiz, R., Curone, G., Kehyaian, V., & Laxague, A. (2012). Characterization of sluggish cognitive tempo construct (SCT). Neuropsychiatrie de l’Enfance et de l’Adolescence, 60(5, Supplement), S135–S136. doi:10.1016/j.neurenf.2012.04.094
- Wietecha, L., Williams, D., Shaywitz, S., Shaywitz, B., Hooper, S. R., Wigal, S. B., Dunn, D., & McBurnett, K. (2013). Atomoxetine improved attention in children and adolescents with attention-deficit/hyperactivity disorder and dyslexia in a 16 week, acute, randomized, double-blind trial. Journal of Child and Adolescent Psychopharmacology. Epub ahead of print.
- Pfiffner L. et al. (2007). "A Randomized, Controlled Trial of Integrated Home-School Behavioral Treatment for ADHD, Predominantly Inattentive Type". J. Am. Acad. Child Adolesc. Psychiatry 46 (8): 1041–1050. doi:10.1097/chi.0b013e318064675f.
- Barkley, R. A., Murphy, K. R., & Fischer, M. (2008). ADHD in adults: What the science says. New York: Guilford Press
- Mahwah, N.J. : Lawrence Erlbaum Associates, c2002- (March 2002). "Sluggish cognitive tempo predicts a different pattern of impairment in the attention deficit hyperactivity disorder, predominantly inattentive type". Journal of clinical child and adolescent psychology : the official journal for the Society of Clinical Child and Adolescent Psychology, American Psychological Association, Division 53. ill (2002): 123–9. doi:10.1207/S15374424JCCP3101_14. PMID 11845644.
- Becker, S. P., & Langberg, J. M. (2012). Sluggish cognitive tempo among young adolescents with ADHD: Relations to mental health, academic, and social functioning. Journal of Attention Disorders. doi:[http://dx.doi.org/10.1177%2F1087054711435411%5D 10.1177/1087054711435411]
- Stephen P. Becker et al.(2013): Reward and punishment sensitivity are differentially associated with ADHD and sluggish cognitive tempo symptoms in children. Journal of Research in Personality. doi: 10.1016/j.jrp.2013.07.001
- Barkley, R. A. (2012). The executive functions: What they are, how they work, and why they evolved. New York: Guilford Press.
- Dr. Barkley presents "Sluggish Cognitive Tempo vs. ADHD: Differences in Nature, Comorbidity, Impairment, and Management" at Psychiatry Grand Rounds at the Medical University of South Carolina Friday, September 7, 2012.
- "The Other Attention Disorder: Sluggish Cognitive Tempo (SCT or ADD) vs. ADHD" by Dr. Barkley (PowerPoint-Slides)
- Article for school psychologists about SCT
- Introduction to the Special Section on SCT in the Journal of Abnormal Child Psychology