J Abnorm Child Psychol (2014) 42:1–6

DOI 10.1007/s10802-013-9825-x

Sluggish Cognitive Tempo in Abnormal Child Psychology:

An Historical Overview and Introduction
to the Special Section
Stephen P. Becker & Stephen A. Marshall &
Keith McBurnett

Published online: 24 November 2013

# Springer Science+Business Media New York 2013

Abstract There has recently been a resurgence of interest in (3) genetic and environmental contributions to the develop-
Sluggish Cognitive Tempo (SCT) as an important construct in ment of SCT symptoms, and (4) functional impairments asso-
the field of abnormal child psychology. Characterized by ciated with SCT. This Special Section brings together papers
drowsiness, daydreaming, lethargy, mental confusion, and to advance the current knowledge related to these issues as
slowed thinking/behavior, SCT has primarily been studied as well as to spur research in this exciting and expanding area of
a feature of Attention-Deficit/Hyperactivity Disorder abnormal psychology.
(ADHD), and namely the predominately inattentive subtype/
presentation. Although SCT is strongly associated with Keywords ADHD . Attention deficit disorder .
ADHD inattention, research increasingly supports the possi- Attention-deficit/hyperactivity disorder . Comorbidity .
bility that SCT is distinct from ADHD or perhaps a different Concentration deficit disorder . DSM-5 . History . SCT .
mental health condition altogether, with unique relations to Sluggish cognitive tempo
child and adolescent psychosocial adjustment. This introduc-
tory article to the Special Section on SCT provides an histor- Sluggish Cognitive Tempo (SCT) is characterized by behav-
ical overview of the SCT construct and briefly describes the ioral symptoms such as drowsiness/sleepiness, seeming to be
contributions of the eight empirical papers included in the “in a fog,” daydreaming, mental confusion, slowness, physi-
Special Section. Given the emerging importance of SCT for cal hypoactivity/lethargy, and apathy. Given these descriptors,
abnormal psychology and clinical science, there is a clear need and as described in more detail below, it is not surprising that
for additional studies that examine (1) the measurement, the study of SCT as a construct largely emerged from inves-
structure, and multidimensional nature of SCT, (2) SCT as tigations of Attention Deficit Disorder (ADD), and, more
statistically distinct from not only ADHD-inattention but also recently, Attention-Deficit/Hyperactivity Disorder (ADHD).
other psychopathologies (particularly depression and anxiety), Given the clear association between SCT and ADHD, there
has been ongoing and increasing interest in whether or not
SCT is empirically distinct from dimensions of ADHD as
S. P. Becker (*) defined by the fourth and fifth editions of the Diagnostic
Department of Psychology, Miami University, 90 North Patterson
and Statistical Manual of Mental Disorders (DSM-IV and
Avenue, Oxford, OH 45056, USA
e-mail: beckersp@miamioh.edu DSM-5 ; American Psychiatric Association [APA] 1994,
2013), as well as the degree to which SCT is itself associated
S. P. Becker with psychosocial functioning and impairment.
Division of Behavioral Medicine and Clinical Psychology,
Indeed, there has been a marked increase in the last dozen
Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, USA
years in the number of studies examining SCT. In order to
S. A. Marshall more clearly illustrate this rise of interest in the topic of SCT, a
Department of Psychology, Ohio University, Athens, OH, USA search of journal articles was conducted using PsycINFO,
PubMed, and GoogleScholar databases. Articles that included
K. McBurnett
Department of Psychiatry, University of California, San Francisco, “sluggish cognitive tempo” (or related terms such as “slow
San Francisco, CA, USA cognitive tempo”) in the title or abstract were identified, as
2 J Abnorm Child Psychol (2014) 42:1–6

were articles that did not mention SCT in the article title/ medical textbook written by Alexander Crichton (Crichton 1798)
abstract but mentioned SCT (or related terms) elsewhere in described two forms of attentional deficits: one involving over-
the article. The number of articles identified in each of these arousal of attentional systems and the other involving
two categories is displayed in Fig. 1. As shown, very few underarousal and low levels of mental energy (see Palmer and
papers explicitly examined or even mentioned SCT between Finger 2001). Study of this underactive form of inattention took a
1985 and 1999. Since 2000, however, there has been a clear back seat to the study of children with observable hyperactivity
and relatively steady increase in the number of studies that and impulsivity (e.g., Laufer et al. 1957). However, work by
focus on SCT or mention SCT in the body of the paper. Many Virginia Douglas in the 1970’s (e.g., Douglas 1972) stressed
of the studies in this latter group make reference to SCT in the that inattention caused more impairment for these children
Discussion of the study findings, highlighting the growing than hyperactivity. Influenced by her work, the DSM-III
awareness of, and interest in, SCT as an important area for (APA 1980) positioned inattention as the core symptom di-
research and clinical attention. It is within this context that the mension under the diagnostic label of Attention Deficit Dis-
set of papers included in this Special Section were prepared. order (ADD; APA 1980). In addition, for the first time, the
Before briefly reviewing the contributions included in the DSM-III allowed for the diagnosis of a subtype that presented
Special Section, we provide an historical overview of the without hyperactivity. This new subtype was formed primarily
study of the SCT construct. to encourage research on nonhyperactive presentations which,
despite being observed clinically, had received little empirical
attention (Milich et al. 2001).
An Historical Overview of SCT SCT took shape as a construct around this same time. Even
as early as the 1960’s and 1970’s, individual SCT symptoms
Conceptualizations of difficulties related to inattention, hyper- (e.g., daydreaming, drowsiness, lethargy, laziness in school)
activity, and impulsivity have undergone several important were included in broadband rating scales for children (e.g.,
changes, both before and after entering the psychiatric nomen- Conners 1969; Peterson 1961; Quay and Quay 1965). How-
clature as Hyperkinetic Reaction of Childhood in the DSM-II ever, whereas many studies indicated that inattention repre-
in 1968 (APA 1968). Although a detailed summary of the sented a separable dimension from hyperactivity (see
history of ADHD is beyond the scope of this article (see Hinshaw 1987, for a review), SCT and other inattention items
Barkley 2006, for a thorough review), the study of SCT is loaded together on a unidimensional inattention factor, such as
closely tied to the study of ADHD. Many early references to the Attentional Problems-Immaturity subscale of the Revised
ADHD-like conditions in the literature, such as Heinrich Behavior Problem Checklist (RBPC; Quay and Quay 1965;
Hoffman’s description of Fidgety Phil in 1865 (Stewart Quay 1983) or the Inattentive-Passive subscale of the Conners
1970) and George Still’s lectures in the Lancet in 1902 (Still Rating Scales (Conners 1969). Interestingly, the single inat-
1902), emphasize overactivity and disinhibition as hallmark tention factor extracted from a wide item pool in a 1971 study
features of the disorder. However, even as early as 1798, a by Dielman, Cattell, and Leeper was even labeled “Sluggish-
ness” because it included SCT-like items (drowsiness, easily
45 fatigued, easily confused, laziness in tasks, and passivity), yet,
40 SCT in Article Text
again, inattentive items (e.g., short attention span, inattentive-
ness to what other say, and distractibility) loaded with these
SCT in Article Title and/or
35 Abstract SCT items.
30 It was not until the mid-1980’s that empirical support for a
Number of Articles

SCT dimension separate from inattention emerged, led in

25
large part by the work of Benjamin Lahey, Ph.D., and Caryn
20 Carlson, Ph.D. (see Carlson 1986). Specifically, in a large,
15
school-based sample, Neeper and Lahey (1986) replicated
the often-found separation of inattention from hyperactivity;
10
however, a factor labeled “Slow Tempo” also emerged that
5 was comprised of sluggish, apathetic, lethargic, drowsy, and
“in a world of his or her own” items. Soon after, Lahey et al.
0
(1988) extracted a comparable sluggish tempo factor (with
forgetful, sluggish, drowsy, and “difficulty following instruc-
Year of Publication
tions” items) in a clinic sample, and found further that a
Fig. 1 Number of journal articles published in print or online between
1985 and 2012 that include sluggish cognitive tempo (SCT) in the article
three-factor model of hyperactivity–impulsivity, inattention–
title/abstract (black fill) or the article body (diagonal line fill). Search was disorganization, and slow tempo provided the best-fitting
conducted using PsycINFO, PubMed, and GoogleScholar databases model of ADD.
J Abnorm Child Psychol (2014) 42:1–6 3

It is important to note that this division of inattention into (i.e., difficulty following instructions, difficulty sustaining
two dimensions also aligned with the division of ADD into attention, trouble listening, loses things, inattention to de-
two subtypes in the DSM-III during the same decade (APA, tails, and disorganization), two symptoms unique to ADD/H
1980). For instance, studies found that inattention subscales (i.e., distractibility and shifts between uncompleted activities),
on commonly used rating scales such as the RBPC and the and four SCT symptoms unique to ADD/noH (i.e., forgetful-
Child Behavior Checklist (CBCL; Achenbach and Edelbrock ness, daydreaminess, sluggishness/drowsiness, and apathy).
1983) did not uniformly apply to both ADD subtypes. Chil- Three of these SCT items–forgetfulness, daydreaminess, and
dren with ADD with hyperactivity (ADD/H) were uniquely sluggishness/drowsiness–were tested in the DSM-IV field tri-
elevated in attentional problems characterized by distractibil- als. Although all three demonstrated strong positive predictive
ity, sloppiness, carelessness, and irresponsibility items, where- power (PPP), the daydreamy and sluggish/drowsy items
as children with ADD without hyperactivity (ADD/noH) were showed poor negative predictive power (NPP), leading the
uniquely elevated in attentional problems characterized work group to decide on a single, parsimonious list of inat-
by sluggishness, drowsiness, slowness, being “lost in a fog,” tention symptoms to be used for diagnosing both subtypes
daydreaming, and apathy (Barkley et al. 1990; Lahey et al. (Frick et al. 1994). Of the proposed SCT symptoms, only the
1985). Once factor analytic work had identified a distinct SCT forgetful item was included in the DSM-IV because it showed
factor, other studies found that SCT scores were uniquely utility for both hyperactive and nonhyperactive subtypes
elevated in children with ADD/noH as compared to children (Frick et al. 1994).
with ADD/H (Lahey et al. 1987, 1988). The exclusion of all but one SCT symptom from the
In an indirect fashion, the validity of SCT was supported by DSM-IV ADHD criteria did not end interest in the construct.
research showing that the two ADD subtypes were associated One reason for continued interest was that research examin-
with a different pattern of external correlates. ADD/H was ing the validity of DSM-IV subtypes was unconvincing (see
uniquely associated with higher levels of aggression, conduct Willcutt et al. 2012), and some thought that the DSM-IV
problems, impulsivity, and peer rejection and lower levels of diagnostic criteria for the new inattentive subtype (ADHD
guilt, whereas ADD/noH was uniquely associated with higher Predominantly Inattentive Type [ADHD-I]), which had been
levels of anxiety, unhappiness, shyness, and peer withdrawal changed considerably from DSM-III criteria, identified too
and lower levels academic performance and math achieve- heterogeneous a group (McBurnett et al. 2001; Milich et al.
ment (see Milich et al. 2001, for a review). Family psychiatric 2001). Many cases with ADHD-I were found to have low
histories also differentiated the groups, as more ADD/H and levels of SCT, while a subset of others with ADHD-I
substance abuse problems were reported in relatives of chil- showed high levels of SCT (Carlson and Mann 2002).
dren with ADD/H and more anxiety and learning problems Further, under DSM-IV criteria, individuals with up to 4 or
were reported in relatives of children with ADD/noH (Barkley 5 symptoms of hyperactivity-impulsivity could be diagnosed
et al. 1990). Although there were rarely differences between with ADHD-I, whereas many others diagnosed with ADHD-
the two subtypes on neuropsychological tests (see Milich et al. I showed very few or no symptoms of hyperactivity-
2001), some studies found that the ADD/H group exhibited impulsivity (see Milich et al. 2001). This variability in
greater problems with disinhibition (Barkley et al. 1991) ADHD-I was highlighted in a collection of commentaries
whereas the ADD/noH group exhibited more problems with in a 2001 issue of Clinical Psychology: Science and Prac-
perceptual-motor speed, automatized processing, and incon- tice , in which a number of ADHD experts argued that
sistent performance on a memory task (Barkley et al. 1990, research into SCT could help specify an important dimension
1991; Hynd et al. 1991). of attentional problems, as well as a distinct classification of
In 1987, the DSM-III-R eliminated the subtyping of ADD attentional disorder (e.g., Milich et al. 2001). In conjunction
and instead created a single disorder named Attention- with these commentaries, an empirical paper by McBurnett
Deficit/Hyperactivity Disorder (ADHD; APA 1987). Howev- et al. (2001) replicated the factor analytic work of Lahey and
er, this decision to remove subtypes was short-lived, as the colleagues from the 1980’s by extracting a similar SCT
DSM-IV Work Group on Disorders Usually First Diagnosed factor (forgetful, daydreams, sluggish/drowsy) in a large
in Infancy, Childhood, or Adolescence decided to revisit ADHD clinic sample. As illustrated in Fig. 1, this group of
subtypes for the classification of ADHD. Influenced by the articles stimulated the growth in SCT research seen over the
DSM-III ADD subtype validation research and SCT factor past dozen years. This growing body of research has focused
analytic work from the 1980’s, the DSM-IV work group on developing more comprehensive measures of SCT symp-
considered incorporating SCT symptoms in the new diagnos- tomatology and, in concert, using factor analysis to validate
tic criteria for a reinstated nonhyperactive subtype of ADHD. the internal and discriminant validity of the SCT construct. It
The DSM-IV Options Book (APA 1991) proposed using two is within this context of renewed interest in the measure-
partially overlapping yet distinct sets of inattention symptoms ment, validity, and correlates of SCT that this Special
to identify each of the subtypes: six overlapping symptoms Section was prepared.
4 J Abnorm Child Psychol (2014) 42:1–6

Special Section Studies functioning, even when the contributions from ADHD symp-
toms are controlled. Watabe et al. (2014, this issue) provide
This Special Section includes eight empirical articles as well the exception: depending on informant and context (school vs.
as a commentary by Russell Barkley, Ph.D. The empirical home), SCT could appear adaptive or maladaptive. Future
articles use an array of sample types and methodologies that resolution of this conundrum might take into account the
together provide an important advance of the current inverse association of SCT with ODD symptoms or behavioral
literature. dysregulation once other psychopathology symptoms are con-
In the literature published up to this date, one of the most trolled (Becker et al. 2014, this issue; Lee et al. 2014, this
consistent findings regarding the internal validity of SCT is issue), and the report from Weinberg and Brumback (1990)
that it constitutes a latent factor that is separate from that of that children with Primary Disorder of Vigilance (a clinical
ADHD Inattention. Of the eight papers herein, four (Becker syndrome with some resemblance to SCT) are unusually
et al. 2014, this issue; Lee et al. 2014, this issue; McBurnett sweet and well-behaved. Likewise, it is possible that SCT
et al. 2014, this issue; Willcutt et al. 2014, this issue) evaluated represents a type of pathological mind wandering (Adams
internal consistency with various methods. All four replicated et al. 2010), which itself may be adaptive in certain circum-
the general finding that SCT represents a distinct latent factor. stances (Smallwood and Schooler 2006). Future research in-
Thus, this particular question—is there such a thing as SCT tegrating these literatures and associated methodologies is of
that is different from ADHD Inattention—seems to be laid to critical importance.
rest as of this issue of JACP because of the consistency with Much of the work in this section evaluates hypotheses
which a separate SCT factor is extracted across methods and drawn from previous literature, but there are also some novel
data sets (note that recent studies also document SCT to be findings. For example, Moruzzi, Rijsdijk, and Battaglia (2014,
distinct from ADHD in adults; Barkley 2012; Becker et al. this issue) report that SCT, in contrast to inattention and
2013). Another question in this literature is whether SCT is a hyperactivity, may be more influenced by non-shared envi-
different construct from internalizing problems in general, and ronmental factors. To our knowledge, this is the first available
from depression more specifically. Three of the papers evidence that SCT has an etiology that differs from ADHD.
(Becker et al. 2014, this issue; Lee et al. 2014, this issue; McBurnett et al. (2014, this issue) report that behaviors that
McBurnett et al. 2014, this issue) pose this question from resemble some aspects of working memory problems may be
different approaches. Overall, the findings suggest that SCT construed as a subfactor of SCT. This new finding is intriguing
and internalizing disorder symptoms are indeed distinct, and but highly preliminary and ripe for further study. Finally, the
that impairment correlated with SCT is not fully explained by Lee et al. (2014, this issue) and the McBurnett et al. (2014, this
the presence of internalizing symptoms. However, to compli- issue) studies employed novel methods of measuring SCT.
cate matters, some authors found that items indicating low Other studies (Langberg et al. 2014, this issue; Willcutt et al.
activity, speed, or energy levels have the potential to confound 2014, this issue) measured SCT using emerging measures that
SCT and depressive factors. It may be that behaviors related to more adequately sample SCT than early studies that used only
sluggishness, a cardinal indicator of SCT, may in fact be a 2-4 items found in existing rating scales. However, the ample
clinically observable feature of SCT, while at the same time contributions made by other papers herein demonstrate that
such behaviors may not be helpful in measures of SCT when measures of SCT that are limited to the few items found on
discriminant validity is the goal. existing rating scales may still be of substantial value in
SCT may be of little consequence if it can only be shown to exploiting archival data.
be psychometrically distinct from ADHD and other psycho-
pathologies but does not also predict meaningful external
constructs. Nearly all of the papers in this Section, including Conclusion
those cited above as well as those from Langberg et al. (2014,
this issue), Marshall et al. (2014, this issue), and Watabe et al. Given the increasing interest in the study of SCT, and studies
(2014, this issue) report on the external correlates of SCT. A documenting its importance, it is an opportune time for a set of
key finding is that some first-order associations that do not papers that together provide a review of SCT-related research
seem to make sense—such as the positive associations of SCT conducted to date, address timely issues in the field, and point
with ADHD hyperactive-impulsive and oppositional defiant toward important research and clinical directions. Interesting-
disorder (ODD) symptoms—seem to become nonexistent (or ly, DSM-5 was published as this Special Section was being
negative in direction) when other psychopathology dimen- prepared. In DSM-IV, SCT was to some extent included under
sions such as ADHD inattention are also included in the model the “Not Otherwise Specified” designation, whereby individ-
(Lee et al. 2014, this issue). Turning to impairment, the uals who did not meet full criteria for ADHD but displayed
general finding of papers in this Special Section is that SCT inattention and “a behavioral pattern marked by sluggishness,
adversely impacts some aspects of social and academic daydreaming, and hypoactivity” could receive an ADHD
J Abnorm Child Psychol (2014) 42:1–6 5

NOS diagnosis. In DSM-5 , symptoms of SCT are no longer Barkley, R. A. (2006). Attention-deficit/hyperactivity disorder: a hand-
book for diagnosis and treatment (3rd ed.). New York: Guilford.
mentioned. In many regards, this is a welcome change, as
Barkley, R. A. (2012). Distinguishing sluggish cognitive tempo from
increasing evidence (including multiple studies in this Special attention deficit hyperactivity disorder in adults. Journal of
Section) provide support for SCT to no longer be subsumed Abnormal Psychology, 121, 978–990.
under the umbrella of ADHD but rather to be considered as Barkley, R. A., DuPaul, G. J., & McMurray, M. B. (1990).
Comprehensive evaluation of attention deficit disorder with and
distinct from it. As such, there is a need for more studies that
without hyperactivity as defined by research criteria. Journal of
do not only examine SCT in ADHD-defined samples, partic- Consulting and Clinical Psychology, 58, 775–789.
ularly as SCT-related research extends to new disciplines and Barkley, R. A., DuPaul, G. J., & McMurray, M. B. (1991). Attention
sub-disciplines (e.g., pediatric psychology; see Becker 2013) deficit disorder with and without hyperactivity: clinical response to
three dose levels of methylphenidate. Pediatrics, 87, 519–531.
in an effort to further understand the causes, correlates, and
Becker, S. P. (2013). Topical review: Sluggish cognitive tempo: research
consequences of SCT. findings and relevance for pediatric psychology. Journal of
On the other hand, the removal of any mention of SCT Pediatric Psychology, 38, 1051–1057. doi:10.1093/jpepsy/jst058.
from DSM-5 may stall research (and, in turn, clinical prac- Becker, S. P., Langberg, J. M., Luebbe, A. M., Dvorsky, M. R., &
Flannery, A. J. (2013). Sluggish cognitive tempo is associated with
tice), as most research conducted in psychology and psychia-
academic functioning and internalizing symptoms in college stu-
try remains wedded to the use of DSM-defined categorical dents with and without attention-deficit/hyperactivity disorder.
diagnoses. While we believe it is premature to consider SCT Journal of Clinical Psychology. doi:10.1002/jclp.22046. Advance
as a psychiatric disorder of its own, researchers should con- online publication.
*Becker, S. P., Luebbe, A. M., Fite, P. J., Stoppelbein, L., & Greening, L.
tinue to investigate this possibility while also pursuing new
(2014). Sluggish cognitive tempo in psychiatrically hospitalized
and novel avenues of research. For example, although highly children: Factor structure and relations to internalizing symptoms,
speculative at this point in time, it is interesting to consider social problems, and observed behavioral dysregulation. Journal of
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