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JADXXX10.1177/1087054714560822Journal of Attention DisordersWood et al.

Article

Executive Dysfunction and Functional Impairment Associated With Sluggish Cognitive Tempo in Emerging Adulthood

Journal of Attention Disorders 1­–10 © 2014 SAGE Publications Reprints and permissions: sagepub.com/journalsPermissions.nav DOI: 10.1177/1087054714560822 jad.sagepub.com

Whitney L. M. Wood1, Lawrence J. Lewandowski1, Benjamin J. Lovett2, and Kevin M. Antshel1

Abstract Objective: Research has identified a relationship between sluggish cognitive tempo (SCT) symptoms and symptoms of ADHD, anxiety, and depression; however, no study has controlled for symptoms of ADHD, anxiety, and depression when examining impairment related to SCT symptoms. This study aimed to examine (a) the extent to which functional impairment and executive function (EF) problems were accounted for by SCT symptoms when controlling for ADHD, anxiety, and depression symptoms, and (b) which type of symptoms were associated with the greatest amount of impairment. Method: College students (N = 458) completed self-report scales of ADHD, SCT, anxiety, and depression symptoms, as well as functional impairment and EF problems. Results: Thirteen percent of the sample was found to have high levels of SCT symptoms. SCT symptoms showed a moderate to strong correlation with the other symptom sets; however, high levels of SCT symptoms often occurred separate from high levels of ADHD, anxiety, or depression symptoms. SCT symptoms accounted for the most unique variance for both EF problems and functional impairment. Students with high levels of SCT symptoms, with or without high levels of ADHD symptoms, exhibited more impairment and EF problems than the controls. Conclusion: SCT is a clinical construct worthy of additional study, particularly among college students. (J. of Att. Dis. XXXX; XX(X) XX-XX) Keywords sluggish cognitive tempo, ADHD, functional impairment, executive function deficits Over the past decade, researchers have paid increasing attention to the sluggish cognitive tempo (SCT) symptom set. SCT symptoms include sluggishness, daydreaming, absentmindedness, and lethargy (Barkley, 2011a; Lahey et al., 1988; Penny, Waschbusch, Klein, Corkum, & Eskes, 2009). Historically, this symptom set has been closely related to the inattentive symptoms of ADHD (Carlson & Mann, 2002; Garner, Marceaux, Mrug, Patterson, & Hodgens, 2010; Hartman et al., 2004). A moderately strong relationship between SCT and internalizing symptoms (i.e., symptoms of depression and/or anxiety) has been identified as well (Barkley, 2012, 2014; Becker & Langberg, 2012; Garner et al., 2010; Garner, Mrug, Hodgens, & Patterson, 2013). Considerable controversy exists over the role of SCT symptoms in diagnosis and mental health; some scholars have suggested that SCT symptoms are a subset of ADHD symptoms (Carlson & Mann, 2002; McBurnett, Pfiffner, & Frick, 2001), whereas others have suggested that SCT is an entirely different type of attention disorder (Barkley, 2012, 2013). SCT symptoms appear to be separable from ADHD symptoms of inattention and hyperactivity as noted in factor analytic studies (Bauermeister, Barkley, Bauermeister,

Martinez, & McBurnett, 2012; Carlson & Mann, 2002; Garner et al., 2010; Lahey et al., 1988; McBurnett et al., 2001). In addition, SCT symptoms are found in populations without ADHD. For example, 40% to 50% of participants with high levels of SCT symptoms lacked high levels of ADHD symptoms in child/adolescent (Barkley, 2013) and adult (Barkley, 2012) samples. Given these findings, Barkley (2013) suggested that the relationship between SCT and ADHD symptoms may be similar to that of anxiety and depression symptoms in that both symptoms sets are distinct yet frequently comorbid. As noted above, numerous studies have demonstrated a relationship between SCT symptoms and symptoms of anxiety and depression in both child/adolescent (Carlson & Mann, 2002; Garner et al., 2010; Garner, Mrug, Hodgens, & 1

Syracuse University, NY, USA SUNY Cortland, NY, USA

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Corresponding Author: Whitney L. M. Wood, Syracuse University, 474 Huntington Hall, University Avenue, Syracuse, NY 13210, USA. Email: [email protected]

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Journal of Attention Disorders 

Patterson, 2013; Hartman et al., 2004) and adult (Barkley, 2012, 2013; Becker & Langberg, 2012) samples. Although some researchers have suggested that SCT may be the byproduct of comorbid ADHD and anxiety disorders (Skirbekk, Hansen, Oerbeck, & Kristensen, 2011), other researchers have found that even after accounting for internalizing symptoms, SCT symptoms remained uniquely associated with inattention (Garner et al., 2013). In addition, SCT symptoms were found to form a separate factor from internalizing symptoms (Becker, Luebbe, Fite, Stoppelbein, & Greening, 2014). These findings highlight the possibly independent, yet highly comorbid, nature of SCT symptoms with ADHD, anxiety, and depression symptoms. If SCT symptoms form a construct that is separate from ADHD, depression, and anxiety symptoms, then another research question is the extent to which SCT symptoms are uniquely associated with functional impairment. Research has found that SCT symptoms are associated with social difficulties (Becker & Langberg, 2012; Carlson & Mann, 2002; Garner et al., 2010; Mikami, HuangPollock, Pfiffner, McBurnett, & Hangai, 2007). Moreover, in college students, SCT symptoms have been associated with school maladjustment and academic impairment, even after controlling for symptoms of ADHD and demographic factors (Becker et al., 2013). However, none of these studies controlled for internalizing disorder symptoms when examining impairment associated with SCT symptoms. Considering the nature of SCT symptoms (daydreaming, being in a fog, sluggishness, etc.) and the social and academic difficulties associated with SCT symptoms, impairment associated with these symptoms might be related to difficulties with executive functions (EF). EFs include skills related to intention/goal-directedness, inhibition, planning, working memory, and self-regulation (Barkley, 1997; Welsh & Pennington, 1988). However, although SCT symptoms have been associated with measures of sustained attention (Wahlstedt & Bohlin, 2010), visual processing speed (Weiler, Bernstein, Bellinger, & Waber, 2002), and early selective attention patterns (Huang-Pollock, Nigg, & Carr, 2005), no relationship has been found between SCT symptoms and indices of inhibitory control, working memory, verbal memory, spatial memory, visual attention, or reaction time (Bauermeister, Barkley, Bauermeister, Martinez, & McBurnett, 2012; Huang-Pollock et al., 2005; Skirbekk et al., 2011; Wahlstedt & Bohlin, 2010). Several studies have examined impairment associated with SCT via EF rating scales. Barkley (2012) administered the Barkley Deficits in Executive Functioning Scale (BDEFS) along with measures of ADHD and SCT to a large general-population sample of adults. The BDEFS assessed five primary EF domains: self-management to time, selfmotivation, self-regulation of emotion, self-organization

and problem solving, and self-restraint. Barkley divided his sample into four groups: those with elevated levels of SCT and ADHD (High SCT + ADHD), those with high levels of ADHD only (High ADHD), those with high levels of SCT only (High SCT), and controls. Across all self-reported EF domains, the High SCT + ADHD group reported the highest level of deficits. However, Barkley found that High SCT participants self-reported more difficulties related to the self-organization and problem-solving domain than did High ADHD participants. Across all four other EF domains, High SCT participants and High ADHD participants reported similar levels of dysfunction. Barkley (2013) also extended his work on SCT and EFs to children and adolescents. He administered the child version of the BDEFS to parents of another general-population sample. Again, Barkley divided the sample into high symptom groups: High SCT + ADHD, High ADHD, High SCT, and controls. Among children and adolescents, Barkley found that while the High SCT group were reported by parents to have higher levels of EF dysfunction than controls, the two high ADHD groups were reported to have more EF deficits across all five domains. ADHD-Inattention (ADHD-I) symptoms accounted for the most variance across all five EF domains, though SCT symptoms did account for a moderate amount of variance for the selforganization and problem-solving domain. Finally, Becker and Langberg (2014) administered the Behavior Rating Inventory of Executive Function (BRIEF) to parents and teachers of 52 youth diagnosed with ADHD. They also assessed SCT symptoms using Penny et al.’s (2009) SCT scale. In regression analyses, parent-reported SCT symptoms were associated with problems with metacognition (i.e., initiation, working memory, tasks demands) above and beyond symptoms of ADHD, but were not associated with problems of behavioral inhibition. Teacherreported ADHD-I symptoms accounted for the most variance for metacognition, though teacher-reported SCT score also accounted for a significant amount of unique variance related to metacognition. These studies indicate that SCT may indeed be associated with EF deficits in adult samples, particularly related to deficits in metacognition and self-organization. However, controversy remains regarding the importance of SCT symptoms in mental health. At present, no study has examined the effect of SCT on both EF and functional impairment while controlling for ADHD, depression, and anxiety symptoms. In addition, no study has yet examined the relationship between SCT symptoms and EF in a college sample, though high levels of SCT symptoms have been reported in college students (Flannery, Becker, & Luebbe, 2014). The discovery of impairment uniquely associated with SCT symptoms after controlling for related symptom sets would suggest that SCT symptoms are a clinically relevant construct worthy of further study.

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Wood et al. The present study examined the extent to which SCT could account for unique variance in the prediction of functional impairment and/or EF problems, while controlling for symptoms of ADHD, anxiety, and depression. Also, high symptom groups were formed to assess which of these groups experienced the most impairment and executive dysfunction.

Method Participants All participants were undergraduate students between the ages of 18 and 24 at a moderately sized private university in the northeastern United States. Students were recruited from undergraduate psychology classes. An e-mail was sent to approximately 800 students providing details regarding the study, and 507 students (63%) responded. All participants received course credit for participating in this study. A total of 507 participants originally participated in this study. Data from 49 participants were excluded due to the participants either failing to complete the entire survey, completing it in an extremely short amount of time (raising questions of response validity), or due to technical problems accessing the survey responses. Therefore, the final sample consisted of 458 participants who fully completed the surveys and met all criteria. The sample was predominantly Caucasian (70%), with 65% of the sample identifying as female, and 35% identifying as male. The sample was distributed across freshman (28%), sophomore (26%), junior (25%), and senior (21%) years. The average age of the sample was 19.91 years of age (SD = 1.59).

Measures Demographic questionnaire. A demographic questionnaire was used to obtain information about the participants’ age, sex/gender, ethnicity, grade point average (GPA), primary language, year in college, and previous psychiatric or medical diagnoses. Barkley Adult ADHD Rating Scale–IV (BAARS-IV). The BAARS-IV (Barkley, 2011a) contains 18 items aligning with Diagnostic and Statistical Manual of Mental Disorders (4th ed., text rev.; DSM-IV-TR; American Psychiatric Association [APA], 2000) criteria for an ADHD diagnosis. Participants answered each item according to a 4-point scale (1 = not at all, 2 = sometimes, 3 = often, and 4 = very often). Items include nine inattention symptoms, six hyperactivity symptoms, three impulsivity symptoms, and nine SCT symptoms. Two types of scores were derived from the BAARS-IV. First, the total symptom score was calculated for ADHD symptoms and SCT symptoms, respectively. Second, the total number of symptoms occurring “often” or

“very often” was used as a clinical cutoff score to divide participants into high symptom groups (i.e., High SCT, High ADHD, and High SCT + ADHD). This scale has high internal consistency (α for Inattention = .90; ADHD Hyperactive–Impulsive [ADHD-HI] = .80; SCT = .90), as reported by Barkley (2011a). Validity of this measure has been demonstrated by high inter-observer agreement between adult respondents and a collateral reporter, with symptom rating scores found to range from r = .59 to .76. Barkley Functional Impairment Scale (BFIS).  The BFIS (Barkley, 2011c) measures the perceived degree of impairment individuals experience in 15 major life activities. Participants responded to each of the 15 activities based on a scale ranging from 0 (no impairment) to 9 (severe impairment). The activities include home life with your immediate family; finishing chores at home and managing your household, work, or occupation; social interactions with friends; activities in the community; any educational activities; marital, co-living, or dating relationships; management of your money, bills, and debts; driving a motor vehicle and your history of citations and accidents; sexual activities and sex relations with others; organization and management of your daily responsibilities; caring for yourself daily; maintaining your health; and taking care of and raising your children. Cumulative scores from these categories result in two outcome scores that were used in this study: (a) the mean functional impairment score and (b) percentage of domains impaired. Individual items were not considered independently. The scale has high internal consistency reliability (α = .97). High inter-observer agreement between adult respondents and a collateral reporter have also demonstrated validity of this measure. The Barkley Deficits in Executive Functioning Scale (BDEFS). The BDEFS (Barkley, 2011b) is an 89-item rating scale used to measure five key domains of deficits in EF. Participants completed the self-report form and rated each item according to a 4-point scale, identical to the previously described BAARS-IV scale. Items on the BDEFS are specifically intended to measure commonly identified constructs under the broader umbrella of EF: inhibition, nonverbal working memory, verbal working memory, organization, problem solving, time management, self-motivation, and self-regulation of emotion (Barkley, 2011b). The five factor-based scales include self-management to time, self-organization and problem solving, self-restraint (inhibition), self-motivation, and self-regulation of emotion. Each of these five scales produced a total score, and these were used as outcome variables. In addition, combining the five subscale scores generates a Total EF score. The internal consistency of these five scales ranges from α = .91 to .96. Barkley (2011b) found that the scales adequately discriminated between clinical and control samples, and others found that

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the scales can significantly predict ADHD in college students (Dehili, Prevatt, & Coffman, 2013). Depression, Anxiety, and Stress Scale (DASS).  The DASS (Lovibond & Lovibond, 1995) is a set of three self-reported scales. These scales are designed to measure the negative emotional states of depression, anxiety, and stress. Each of the three scales contains 14 items. The depression scale assesses the following symptoms: dysphoria, hopelessness, devaluation of life, self-depreciation, lack of interest/involvement, anhedonia, and inertia. The anxiety scale assesses the following symptoms: autonomic arousal, skeletal muscle effects, situational anxiety, and subjective experience of anxious affect. The stress scale assesses the following symptoms: difficulty relaxing, nervous arousal, being easily upset/agitated, irritable/over-reactive, and impatient. Participants were asked to rate the severity of each symptom using a 4-point scale to the extent that they have experienced the symptom over the past week. The internal consistency reliability estimates for the Depression, Anxiety, and Stress subscales range from α = .89 to .97 (Antony, Bieling, Cox, Enns, & Swinson, 1998; Brown, Chorpita, Korotitsch, & Barlow, 1997; Zlomke, 2009). Validity of this measure has been demonstrated by strong correlations between the DASS and other recognized measures of anxiety and depression symptoms (Lovibond & Lovibond, 1995).

Procedures An online survey was distributed to college students via an online survey engine. All participants completed the survey independently; there was no group administration. Participants completed rating scales first on DSM-IV-TR ADHD symptoms and SCT symptoms, then anxiety and depression symptoms, functional impairment, and EF deficits. Throughout the survey, all participants had a visual reminder at the top of the screen that prompted them to answer all questions as honestly and as accurately as possible. Also, all students were instructed that if they were prescribed medication for a mental health diagnosis or illness, they should answer questions as if they were not on the medication. Determining high levels of symptoms.  Individuals were identified as having a symptom of ADHD or SCT if they rated the symptom as occurring “often” or “very often” on the BAARSIV or the SCT rating scale (described below). This is consistent with the DSM-IV-TR requirement that symptoms occur “often” or “very often.” Also consistent with the DSM-IV-TR criteria, a symptom count of six or more symptoms being rated as “often” or “very often” was used to distinguish individuals with clinical or “high” levels of ADHD-I and/or ADHD-HI symptoms. Consistent with Barkley (2012), a symptom count of five or more SCT symptoms being rated as “often” or “very often” was used to distinguish individuals

with clinically “high” levels of SCT symptoms. Participants were identified as having clinically “high” symptoms of anxiety or depression if they reported a total score of 20 or above for anxiety symptoms and a total score of 28 or above for depression symptoms on the DASS. These are the cutoff criteria for “extremely severe” levels of anxiety or depression symptoms provided in the DASS manual. This conservative estimate of elevated levels of anxiety and depression symptoms may have contributed to our limited numbers of individuals who qualified as High Anxiety and High Depression. Table 1 lists the means and standard deviations of both predictor and outcome variables for each group (Controls, High SCT, High ADHD, and High SCT + ADHD), while Table 2 displays the mean number of SCT, ADHD-I, ADHD-HI, anxiety, and depression symptoms for each group. Identification of high symptom groups. The total symptom number from the BAARS-IV (Barkley, 2011a) and symptom scores from the DASS (Lovibond & Lovibond, 1995) were used to create four groups: high levels of SCT symptoms (High SCT; n = 45), high levels of ADHD symptoms (High ADHD; n = 10), high levels of both SCT symptoms and ADHD symptoms (High SCT + ADHD; n = 15), and controls (those not qualifying for any of the other groups; n = 388). There were too few individuals with high levels of anxiety symptoms alone (n = 5) or depression symptoms alone (n = 2) to form those clinical groups. The results of our analyses did not change regardless of whether individuals with high levels of anxiety and/or depression symptoms were included or excluded from the high symptom groups. Therefore, these individuals were distributed among the four groups (see Table 2).

Results Sample Characteristics No significant differences were found between groups with regard to sex, χ2(3, N = 458) = 1.10, p = .78; year in school, χ2(3, N = 458) = 2.21, p = .53; ethnicity, χ2(3, N = 458) = 3.21, p = .36; or age, F(3, N = 458) = 3.44, p = .33. The groups differed significantly by GPA, χ2(3, N = 458) = 13.79, p = .003. The High ADHD group had a significantly lower GPA than controls, U = 929.50, p = .005. The High ADHD group also had a significantly lower GPA than did those in the High SCT + ADHD group, U = 20.00, p = .002. Regarding medication use, only 14 participants reported taking an ADHD medication. All of these individuals fell into the control group. None of the members of the high symptom groups reported taking medication for ADHD symptoms. Therefore, with the exception of GPA, the High SCT group and the High SCT + ADHD group did not differ significantly from controls or from one another. These findings indicate that, with a few academic exceptions, group demographics were similar.

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Wood et al. Table 1.  Means and Standard Deviations of Predictor and Outcome Variables for High Symptom Groups. Group   Variables ADHD-I symptoms ADHD-HI symptoms SCT symptoms Anxiety symptoms Depression symptoms FI mean score EF total score

1. Control

2. SCT

3. ADHD

4.SCT + ADHD

  2

M (SD)

M (SD)

M (SD)

M (SD)

χ + contrasts

0.65 (1.11) 1.20 (1.18) 1.05 (1.23) 3.76 (4.97) 4.09 (5.90) 1.48 (1.41) 132.23 (31.42)

2.60 (1.70) 2.04 (1.52) 5.80 (0.84) 11.87 (6.56) 17.69 (10.82) 3.61 (1.44) 195.42 (26.77)

5.10 (3.25) 7.70 (1.77) 3.00 (1.15) 4.70 (4.79) 5.80 (5.07) 2.36 (1.87) 189.40 (44.01)

7.53 (.99) 3.73 (2.55) 6.80 (1.21) 14.67 (10.93) 17.87 (8.86) 4.82 (2.69) 245.80 (38.08)

127.31**; 1 < 2 < 3 < 4 53.81**; 1 < 2 < 3, 4 181.52**; 1 < 3 < 2, 4 88.41**; 1, 3 < 2, 4 100.24**; 1 < 3 < 2, 4 88.64**; 1, 3 < 2, 4 122.23**; 1 < 3, 2 < 4

Note. Control = college sample control group that does not qualify for any of the high symptom groups; SCT = sluggish cognitive tempo; ADHD = ADHD only; SCT + ADHD = qualifies for both SCT and ADHD high symptoms; chi-square + contrasts = the results of the non-parametric chi-square test. Where the test was significant, the results of the group contrasts are shown as well. ADHD-I = number of ADHD Inattention symptoms; ADHDHI = number of ADHD hyperactive-impulsive symptoms; anxiety symptoms = score on the DASS in the anxiety domain; depression symptoms = score on the DASS in the depression domain; FI = functional impairment; EF = executive function; DASS = Depression, Anxiety, and Stress Scale. **p < .001.

Table 2.  Frequency and Percentage of Participants With Elevated Symptoms. Classification High SCT-only group1 High ADHD only group2 High SCT + ADHD group3 Controls SCT alone1 ADHD alone2 SCT + ADHD3 Anxiety alone SCT + Anxiety1 Depression alone SCT + Depression1 SCT + Anxiety + ADHD3 SCT + Anxiety + Depression1 Anxiety + Depression SCT + ADHD + Depression3 SCT, ADHD, Anxiety, + Depression3

Number of cases

% of sample (N = 458)

45 10 15 388 33 10 10 5 2 2 6 3 4 1 1 1

9.8 2.2 3.3 84.7 7.2 2.2 2.2 1

Executive Dysfunction and Functional Impairment Associated With Sluggish Cognitive Tempo in Emerging Adulthood.

Research has identified a relationship between sluggish cognitive tempo (SCT) symptoms and symptoms of ADHD, anxiety, and depression; however, no stud...
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