Sluggish Cognitive Tempo Symptoms Contribute to Heterogeneity in Adult Attention-Deficit Hyperactivity Disorder

Attention-deficit hyperactivity disorder (ADHD) persists into adulthood in over 50% of cases, although its associated symptom profiles, comorbid problems, and neuropsychological deficits change substantially across development. Sluggish cognitive tempo (SCT) symptoms may contribute to associations between ADHD and comorbid problems and may partially explain the substantial heterogeneity observed in its correlates. 349 adults aged 18–38 years (M = 23.2, SD = 4.5, 54.7% male, 61.03% with ADHD) completed a multi-informant diagnostic procedure and a comprehensive neuropsychological battery. Adults with ADHD (n = 213) were retained for analyses. Latent class analyses (LCA) revealed three profiles of SCT symptoms among those with ADHD, which we classified as minimal, moderate, or severe SCT. Multiple analysis of covariance (MANCOVA) revealed significant differences among these profiles, which remained when controlling for persistence of ADHD symptoms and sex. In general, adults with ADHD combined with SCT symptoms (moderate and severe) had significantly more symptoms of anxiety, depression, and persistent inattention, and had more severe professional and relational impairment compared to ADHD adults without SCT. Compared to those with moderate or minimal SCT symptoms, the severe SCT group had the most symptoms of depression and internalizing disorders, and the most impairment in the domain of daily responsibility. No significant differences based on externalizing symptoms emerged when controlling for sex and persistence of inattention symptoms, suggesting the moderate and severe SCT groups do not simply reflect more symptoms. Moreover, follow-up mediation analyses revealed that SCT might at least partially explain the heterogeneity in ADHD. Findings have implications for refinement of etiological conceptualization, assessment methods, and intervention strategies.     

Sluggish Cognitive Tempo as a Transdiagnostic Link Between Adult ADHD and Internalizing Symptoms

Although absent from traditional diagnostic nosologies, Sluggish Cognitive Tempo (SCT) may have transdiagnostic utility given its robust associations with ADHD and internalizing symptoms as well as with cognitive impairments common to these conditions. Within-person variation in SCT symptoms may also serve to link ADHD, cognitive deficits, and internalizing psychopathology, however, few studies have utilized intensive longitudinal designs to probe within-person variation in SCT and its links to cognitive deficits and psychopathology. Ecological Momentary Assessment was used to measure between and within-person variance in SCT 4 times per day across 7 days (28 time-points) in 158 college students (approximately 51% with elevated ADHD and/or internalizing symptoms). Participants also completed ratings of current and childhood ADHD symptoms, cognitive function and internalizing psychopathology. Parameters derived from longitudinal multilevel models indexing between and within person variation in SCT were examined as mediators of the associations between (1) ADHD and internalizing symptoms and (2) self-reported cognitive functioning and internalizing symptoms. Results indicated that between-person differences in SCT, but not within-person variability, linked current and childhood ADHD and internalizing symptoms. Similarly, problems in time-management and organization influenced internalizing psychopathology via between-person differences in SCT. Results found that SCT may be a transdiagnostic link bridging mental health comorbidities, cognitive dysfunction, and internalizing psychopathology.

     

WISC-IV and WISC-III profiles in children with ADHD

Wechsler Intelligence Scale for Children, 3rd and 4th editions (WISC-III n = 586 and WISC-IV n = 118), profiles were compared for children with ADHD and normal intelligence. Mean Verbal Comprehension Index (VCI) and Perceptual Organization/Perceptual Reasoning Index (POI/PRI) scores were significantly higher than Freedom From Distractibility/Working Memory Index (FDI/WMI) and Processing Speed Index (PSI), and Symbol Search was higher than Coding. FDI/WMI and PSI scores were similar on both tests, but VCI and POI/PRI were higher on the WISC-IV than on the WISC-III. Therefore, index discrepancies were greater for the WISC-IV, suggesting that the WISC-IV might be better than the WISC-III in delineating the strengths and weaknesses of children with ADHD. All children in the WISC-IV sample scored lowest on WMI or PSI, whereas only 88% of the WISC-III children scored lowest on FDI or PSI. Thus, the WISC-IV may be more helpful in diagnosing ADHD than the WISC-III.     

Dimensions and Correlates of Attention Deficit/Hyperactivity Disorder and Sluggish Cognitive Tempo

The present study examined Sluggish Cognitive Tempo (SCT) in relation to ADHD symptoms, clinical diagnosis, and multiple aspects of adjustment in a clinical sample. Parent and teacher reports were gathered for 322 children and adolescents evaluated for behavioral, emotional, and/or learning problems at a university clinic. Confirmatory factor analyses (CFA) supported the presence of three separate, but correlated factors (SCT, inattention, and hyperactivity/impulsivity) in both parent and teacher ratings. As expected, SCT symptoms were greatest in youth with ADHD Inattentive type, but were also found in non-ADHD clinical groups. SCT symptoms were related to inattention, internalizing, and social problems across both parent and teacher informants; for parent reports, SCT was also related to more externalizing problems. Findings support the statistical validity of the SCT construct, but its clinical utility is still unclear.     

Sluggish Cognitive Tempo in Psychiatrically Hospitalized Children: Factor Structure and Relations to Internalizing Symptoms, Social Problems, and Observed Behavioral Dysregulation

As research examining sluggish cognitive tempo (SCT) advances, it is important to examine the structure and validity of SCT in a variety of samples, including samples of children who are clinically-distressed but not referred specifically for attention-deficit/hyperactivity disorder (ADHD). The present study used a large sample of psychiatrically hospitalized children (N?=?680; 73 % male; 66 % African American) between the ages of 6 and 12 to examine the latent structure of SCT, ADHD, oppositional defiant disorder (ODD), depression, and anxiety using confirmatory factor analysis (CFA). Results of the CFA analyses demonstrated that SCT is distinct from these other dimensions of child psychopathology, including ADHD inattention, depression, and anxiety. Regression analyses indicated that SCT symptoms were positively associated with depression and, to a lesser degree, anxiety. SCT symptoms were also positively associated with children’s general social problems, whereas SCT symptoms were negatively associated with an observational measure of behavioral dysregulation (i.e., frequency of time-outs received as a part of a manualized behavior modification program). These associations were significant above and beyond relevant child demographic variables (i.e., age, sex, race), children’s other mental health symptoms (i.e., ADHD, ODD, depression, anxiety symptoms), and, for all relations except child anxiety, parents’ own anxiety and depression symptoms.     

Sluggish cognitive tempo in children and adolescents with higher functioning autism spectrum disorders: Social impairments and internalizing symptoms

Sluggish cognitive tempo (SCT) was introduced in 1980s in the field of attention deficit hyperactivity disorder (ADHD). Studies indicate that symptoms of SCT are separate from symptoms of ADHD and independently associated with multiple domains of functioning in clinical groups and in typical development. We assessed whether similar pattern would apply to higher functioning autism spectrum disorders (ASD). Children with higher functioning ASD (N = 55; 5?15 years) were divided into the ASD+High SCT (n = 17), the ASD+Medium SCT (n = 18) and the ASD+Low SCT (n = 20) groups based on parent‐rated daydreaming and slowness on the Five to Fifteen questionnaire (FTF). The groups were compared on SCT‐related impairments found in previous studies: social skills, academic functioning, psychiatric symptoms, and processing speed. Assessment methods were the FTF, the Development and Well‐Being Assessment, and the Coding subtest of the WISC‐III. The ADHD symptoms were statistically controlled due to the overlap between SCT and ADHD. The ASD+High SCT and ASD+Medium SCT groups were significantly more likely to have the most pronounced social impairments, and the ASD+High SCT group had significantly higher rate of internalizing disorders compared to the ASD+Low SCT group. Our results suggest that children with higher functioning ASD and high or medium levels of SCT symptoms could be at higher risk for psychosocial impairments than children with higher functioning ASD with low levels of SCT symptoms. Co‐occurring ADHD symptoms do not explain the finding. Recognizing SCT symptoms in higher functioning ASD would be important to targeting preventive support.     

Are sluggish cognitive tempo symptoms associated with executive functioning in preschoolers?

The aim of this study is to investigate whether sluggish cognitive tempo (SCT) symptoms are associated with neurocognitive task performance and ratings of real-world executive functioning (EF) in preschoolers at risk for attention-deficit/hyperactivity disorder (ADHD). The associations between parent- and teacher-rated SCT symptoms and neuropsychological task performance and ratings of EF in 61 4-year-old preschool children (51 boys, 10 girls) with self-regulation difficulties were examined, with regression analyses controlling for the effects of ADHD inattention symptoms. In the study sample, higher teacher-rated SCT symptoms are significantly associated with poorer performance on tasks of visual-perceptual abilities, auditory and visual attention, sustained and selective attention, inhibitory control, pre-numerical/numerical concepts, and slower processing speed, but SCT symptoms are not significantly associated with working memory, attention shifting or cognitive flexibility when controlling for ADHD inattention. Higher parent-rated SCT symptoms are significantly associated with visual-perceptual abilities. ADHD inattention symptoms are more strongly associated than SCT with daily life EF ratings; neither parent- nor teacher-rated SCT symptoms are significantly associated with daily life ratings of inhibition, working memory, or planning/organization after controlling for ADHD inattention. This study suggests that SCT symptoms contribute to EF deficits at least on neurocognitive tasks assessing visual-perceptual/spatial abilities, attention to detail and processing speed, as observed in this sample of young children at risk for ADHD, and may be an important intervention target.     

Validity of the Sluggish Cognitive Tempo, Inattention, and Hyperactivity Symptom Dimensions: Neuropsychological and Psychosocial Correlates

This study examined the latent structure and validity of inattention, hyperactivity-impulsivity, and sluggish cognitive tempo (SCT) symptomatology. We evaluated mother and teacher ratings of ADHD and SCT symptoms in 140 Puerto Rican children (55.7% males), ages 6 to 11?years, via factor and regression analyses. A three-factor model (inattention, hyperactivity-impulsivity, and SCT) provided the best fit for both sets of ratings. Inattention was the strongest correlate of lower scores on neuropsychological, achievement, and psychosocial measures. Externalizing problems were most strongly associated with hyperactivity-impulsivity, and internalizing problems were most strongly associated with parent-rated SCT and teacher-rated Inattention. SCT was not associated with executive function but was negatively associated with math. Inattention accounted for a disproportionate amount of ADHD-related impairment, which may explain the restricted discriminant validity of DSM-IV types. The distinct factors of hyperactivity-impulsivity and SCT had unique associations with impairing comorbidities and are roughly equivalent in predicting external correlates of ADHD-related impairment.     

Which components of processing speed are affected in ADHD subtypes?

The term “processing speed” (PS) encompasses many components including perceptual, cognitive and output speed. Despite evidence for reduced PS in Attention-Deficit/Hyperactivity Disorder (ADHD), little is known about which component(s) is most impacted in ADHD, or how it may vary by subtypes. Participants included 151 children, ages 8–12 years, with ADHD Predominantly Inattentive Type, ADHD Combined Type and typically developing controls using DSM-IV criteria. All children completed four measures of processing speed: Symbol Search, Coding, Decision Speed, and simple reaction time. We found children with ADHD-PI and ADHD-C had slower perceptual and psychomotor/incidental learning speed than controls and that ADHD-PI had slower decision speed than controls. The subtypes did not differ on any of these measures. Mean reaction time was intact in ADHD. Hence, at a very basic output level, children with ADHD do not have impaired speed overall, but as task demands increase their processing speed becomes less efficient than controls’. Further, perceptual and psychomotor speed were related to inattention, and psychomotor speed/incidental learning was related to hyperactivity/impulsivity. Thus, inattention may contribute to less efficient performance and worse attention to detail on tasks with a higher perceptual and/or psychomotor load; whereas hyperactivity/impulsivity may affect psychomotor speed/incidental learning, possibly via greater inaccuracy and/or reduced learning efficiency. Decision speed was not related to either dimension. Results suggest that PS deficits are primarily linked to the inattention dimension of ADHD but not exclusively. Findings also suggest PS is not a singular process but rather a multifaceted system that is differentially impacted in ADHD.     

Social and Academic Impairment in Youth with ADHD, Predominately Inattentive Type and Sluggish Cognitive Tempo

Sluggish cognitive tempo (SCT) was originally identified as a construct that characterized the inattention problems of some children with attention deficit disorder (ADD). Research has indicated that using SCT symptoms to identify a subset of youth with attention-deficit/hyperactivity disorder, predominately inattentive type (ADHD-IT) may elucidate distinct patterns of impairment and thereby improve the external validity of ADHD subtypes. The objective of the current study was to investigate whether youth with clinically-assessed ADHD-IT and high levels of SCT exhibit unique social and academic impairments. In a clinic-referred sample of youth (N?=?209; 23 % female) aged 6 to 17 years, participants who met criteria for three different groups were identified: ADHD, Combined Type (ADHD-CT; n?=?80), ADHD-IT with low SCT symptoms (n?=?74), and ADHD-IT with high SCT symptoms (n?=?55). These groups were compared on indicators of social and academic functioning while considering the effects of co-occurring internalizing and disruptive behavior disorders. Youth with ADHD-IT high in SCT exhibited uniquely elevated withdrawal, as well as low leadership and low peer-directed relational and overt aggression, which were not accounted for by co-occurring disorders. This high-SCT group was also the only group to have more homework problems than the ADHD-CT group, but only when other disruptive behavior disorders were absent. The distinctiveness of the high-SCT group, which was primarily evident in social as opposed to academic functioning, provides partial support for the external validity and clinical utility of SCT.     

Factor Structure of a Sluggish Cognitive Tempo Scale in Clinically-Referred Children

“Sluggish cognitive tempo” (SCT) is a construct hypothesized to describe a constellation of behaviors that includes daydreaming, lethargy, drowsiness, difficulty sustaining attention, and underactivity. Although the construct has been inconsistently defined, measures of SCT have shown associations with symptoms of attention-deficit/hyperactivity disorder (ADHD), particularly inattention. Thus, better characterization of SCT symptoms may help to better predict specific areas of functional difficulty in children with ADHD. The present study examined psychometric characteristics of a recently developed 14-item scale of SCT (Penny et al., Psychological Assessment 21:380–389, 2009), completed by teachers on children referred for outpatient neuropsychological assessment. Exploratory factor analysis identified three factors in the clinical sample: Sleepy/Sluggish, Slow/Daydreamy, and Low Initiation/Persistence. Additionally, SCT symptoms, especially those loading on the Sleepy/Sluggish and Slow/Daydreamy factors, correlated more strongly with inattentive than with hyperactive/impulsive symptoms, while Low Initiation/Persistence symptoms added significant unique variance (over and above symptoms of inattention) to the predictions of impairment in academic progress.     

Sleep disturbance and neuropsychological function in young children with ADHD

Sleep disturbance, common among children with ADHD, can contribute to cognitive and behavioral dysfunction. It is therefore challenging to determine whether neurobehavioral dysfunction should be attributed to ADHD symptoms, sleep disturbance, or both. The present study examined parent-reported sleep problems (Children’s Sleep Habits Questionnaire) and their relationship to neuropsychological function in 64 children, aged 4–7 years, with and without ADHD. Compared to typically developing controls, children with ADHD were reported by parents to have significantly greater sleep disturbance—including sleep onset delay, sleep anxiety, night awakenings, and daytime sleepiness—(all p ≤ .01), and significantly poorer performance on tasks of attention, executive control, processing speed, and working memory (all p < .01). Within the ADHD group, total parent-reported sleep disturbance was significantly associated with deficits in attention and executive control skills (all p ≤ .01); however, significant group differences (relative to controls) on these measures remained (p < .01) even after controlling for total sleep disturbance. While sleep problems are common among young children with ADHD, these findings suggest that inattention and executive dysfunction appear to be attributable to symptoms of ADHD rather than to sleep disturbance. The relationships among sleep, ADHD symptoms, and neurobehavioral function in older children may show different patterns as a function of the chronicity of disordered sleep.     

Pre-existing Perceptions of ADHD Predict Children’s Sociometrics Given to Classmates with ADHD

Considerable research documents that even young children possess stigma about mental illness, which may affect how they evaluate peers with mental health conditions. This study examined children’s pre-existing perceptions of Attention Deficit/Hyperactivity Disorder (ADHD) behaviors as predictors of their subsequent sociometric judgments of classmates with ADHD in a 2-week summer day camp. Participants were previously unacquainted children ages 6.8–9.8 years (113 typically-developing and 24 with ADHD; 48.2% boys; 81% White). Children initially more inclined to interact with a hypothetical classmate with ADHD gave fewer “dislike” nominations to real-life classmates with ADHD at camp. Children who initially believed that ADHD symptoms were uncontrollable gave more “dislike” nominations and lower liking ratings to classmates with ADHD when those classmates displayed severe ADHD symptoms. For children who had ADHD, their attribution of uncontrollability for ADHD symptoms predicted fewer “like” nominations and more “dislike” nominations given to classmates with ADHD. Lastly, children who initially reported they would help a hypothetical classmate with ADHD gave higher liking ratings to classmates with ADHD. These results were found after statistical control of the actual level of ADHD behaviors displayed by the classmates with ADHD. In summary, other children’s pre-existing or stigmatizing perceptions of ADHD behaviors may contribute, in part, to the substantial peer rejection typically experienced by ADHD populations. Findings have implications for understanding peer problems in children with this common mental health condition.     

ADHD and Depression Symptoms in Parent Couples Predict Response to Child ADHD and ODD Behavior

Parents of children with attention-deficit hyperactivity disorder (ADHD) and oppositional defiant disorder (ODD) often have elevated ADHD and depressive symptoms, both of which increase the risk of ineffective parenting and interparental discord. However, little is known about whether child ADHD/ODD behavior and parent ADHD or depressive symptoms uniquely or synergistically predict the quality of parenting and interparental communication during triadic (mother-father-child) interactions. Ninety parent couples, including 51 who have children diagnosed with ADHD, were randomly assigned to interact with a 9–12 year-old confederate child (84 % male) exhibiting either ADHD/ODD-like behavior or typical behavior. Parents reported their own ADHD and depressive symptoms, and parents and observers rated the quality of parenting and interparental communication during the interaction. Actor-partner interdependence modeling indicated that child ADHD/ODD behavior predicted less positive and more negative parenting and communication, independent of adult ADHD and depressive symptoms. Parent couples including two parents with elevated ADHD communicated more positively while managing children exhibiting ADHD/ODD behavior than couples managing children behaving typically or couples with only one parent with elevated ADHD symptoms. Couples including one parent with, and one parent without, elevated ADHD or depressive symptoms parented less positively and more negatively, and communicated more negatively, when managing children exhibiting ADHD/ODD behavior than when managing children behaving typically. Taken together, depending on the similarity of ADHD and depressive symptom levels in parent couples, adults managing children exhibiting ADHD/ODD behavior may parent or communicate positively or negatively. Findings highlight the need to consider the psychopathology of both parents when treating children with ADHD in two-parent homes.     

Adult ADHD: Associations with Personality and Other Psychopathology

The goals of this study were to explicate adult ADHD’s relations with personality at both the domain and facet levels and to examine its associations with other psychological symptoms. Community members (N?=?294) completed measures assessing ADHD inattentive and hyperactive/impulsive symptoms, five-factor model personality domains and facets, and other internalizing and externalizing symptoms. Inattentiveness showed strong negative relations with conscientiousness and extraversion and strong positive relations with neuroticism; in contrast, hyperactivity/impulsivity related negatively to agreeableness, positively to extraversion, and weakly to neuroticism. Whereas inattentiveness emerged as a positive predictor of internalizing psychopathology—and depression in particular—hyperactivity/impulsivity related weakly to internalizing but more strongly to externalizing psychopathology. Thus, inattentive and hyperactive/impulsive symptoms showed differential relations with personality—at both the domain and facet levels—and with other psychological symptoms. These results demonstrate the value in examining ADHD’s relations with personality facets and with a wide range of psychopathology within the same study.     

Naming speed as a predictive diagnostic measure in reading and attentional problems

This study aimed to describe and compare naming speed abilities in children diagnosed with either Reading Learning Difficulties (RLD) or Attention Deficit/Hyperactivity Disorder (ADHD), or comorbidity for both (ADHD+RLD). To examine the explanatory power of naming speed and ADHD symptomatology in predicting group associations (while controlling for gender and age), the “Rapid Automatized Naming and Rapid Alternating Stimulus Tests” (RAN/RAS) were utilized. A sample of 101 children (age range = 5–16 years) was divided into four groups: RLD (n = 14), ADHD (n = 28), comorbid (n = 19), and control (n = 40). There were statistically significant differences in RAN/RAS results among the diagnostic groups. Moreover, discriminant analysis revealed that naming speed tasks significantly predicted reading and attentional problems, especially at earlier ages. These results demonstrate the potential usefulness of RAN/RAS in the diagnosis of reading and attentional problems, particularly if the children are aged from 5 to 9.     

The Internal and External Validity of Sluggish Cognitive Tempo and its Relation with DSM–IV ADHD

Studies of subtypes of DSM-IV attention-deficit/hyperactivity disorder (ADHD) have provided inconsistent support for the discriminant validity of the combined type (ADHD-C) and predominantly inattentive type (ADHD-I). A large sample of children and adolescents with ADHD (N?=?410) and a comparison group without ADHD (N?=?311) were used to test the internal and external validity of sluggish cognitive tempo (SCT), a dimension characterized by low energy and sleepy and sluggish behavior. SCT scores were then incorporated in analyses of ADHD subtypes to test whether the discriminant validity of ADHD-C and ADHD-I could be improved by including SCT symptoms as part of the criteria for ADHD-I. Factor analyses of parent and teacher ratings indicated that six SCT items loaded on a factor separate from symptoms of ADHD and other psychopathology, providing important support for the internal validity of SCT. The external validity of SCT was supported by significant associations between SCT and measures of functional impairment and neuropsychological functioning when symptoms of ADHD and other psychopathology were controlled. However, contrary to initial predictions, high levels of SCT did not identify a subgroup of ADHD-I that was clearly distinct from ADHD-C. Instead, the current results suggest that DSM-IV inattention and SCT are separate but correlated symptom dimensions that are each independently associated with important aspects of functional impairment and neuropsychological functioning.     

Rapid automatized naming (RAN) in children with ADHD: An ex-Gaussian analysis

Children with ADHD demonstrate increased frequent “lapses” in performance on tasks in which the stimulus presentation rate is externally controlled, leading to increased variability in response times. It is less clear whether these lapses are also evident during performance on self-paced tasks, e.g., rapid automatized naming (RAN), or whether RAN inter-item pause time variability uniquely predicts reading performance. A total of 80 children aged 9 to 14 years—45 children with attention-deficit/hyperactivity disorder (ADHD) and 35 typically developing (TD) children—completed RAN and reading fluency measures. RAN responses were digitally recorded for analyses. Inter-stimulus pause time distributions (excluding between-row pauses) were analyzed using traditional (mean, standard deviation [SD], coefficient of variation [CV]) and ex-Gaussian (mu, sigma, tau) methods. Children with ADHD were found to be significantly slower than TD children (p < .05) on RAN letter naming mean response time as well as on oral and silent reading fluency. RAN response time distributions were also significantly more variable (SD, tau) in children with ADHD. Hierarchical regression revealed that the exponential component (tau) of the letter-naming response time distribution uniquely predicted reading fluency in children with ADHD (p < .001, ΔR² = .16), even after controlling for IQ, basic reading, ADHD symptom severity and age. The findings suggest that children with ADHD (without word-level reading difficulties) manifest slowed performance on tasks of reading fluency; however, this “slowing” may be due in part to lapses from ongoing performance that can be assessed directly using ex-Gaussian methods that capture excessively long response times.     

Evaluating the Utility of Sluggish Cognitive Tempo in Discriminating Among <Emphasis Type="Italic">DSM-IV</Emphasis> ADHD Subtypes

The objective of the current study was to evaluate how the inclusion of 3 Sluggish Cognitive Tempo (SCT) symptoms in Attention-Deficit/Hyperactivity Disorder (ADHD) diagnostic criteria influences the external validity of the ADHD subtypes. The sample comprised 228 children (166 boys, 62 girls) ranging in age from 5–18 years who were referred to clinics for attentional, behavioral, and/or learning problems and diagnosed with DSM-IV ADHD (124 Combined type, 81 Inattentive type, 23 Hyperactive-Impulsive type). Parent ratings of ADHD symptoms were obtained using the Emory Combined Rating Scale (ECRS), which assesses symptoms of the common DSM-IV childhood psychiatric disorders. Regression analyses incorporating planned comparisons were conducted to examine how the inclusion of SCT symptoms affects differences among ADHD subtypes on several external validity indicators (i.e., gender, age-of-onset, and overlapping conditions). The regression analyses did not yield any significant differences in gender ratios, mean age-of-onset, or overlapping externalizing or internalizing problems when the ADHD Inattentive type was subdivided into high- versus low-SCT groups. In conclusion, the current results suggest that the inclusion of parent-reported SCT symptoms in the ADHD diagnostic criteria has limited utility for isolating diagnostically meaningful subgroups of the Inattentive type or for enhancing the external validity of the ADHD subtypes in clinic-referred samples.     

Internal and External Validity of Self-Report and Parent-Report Measures of Sluggish Cognitive Tempo in South Korean Adolescents

This study evaluated the internal and external validity of self-report and parent-report measures of sluggish cognitive tempo (SCT) in South Korean adolescents. Adolescents (N =?469, ages 13–17 years; 50.2% boys) completed self-report measures of SCT and attention-deficit/hyperactivity disorder inattention (ADHD-IN) in addition to measures of internalizing and externalizing psychopathology, social problems, and grades. Parents rated adolescents on SCT, ADHD-IN, internalizing and externalizing psychopathology, and social problems. Using adolescent self-report, 11 of 15 SCT symptoms showed convergent and discriminant validity with ADHD-IN. Using parent-report, all 15 SCT symptoms showed convergent and discriminant validity with ADHD-IN. For within source analyses, SCT showed unique and stronger associations than ADHD-IN with internalizing psychopathology whereas ADHD-IN showed unique and stronger associations than SCT with externalizing psychopathology. SCT and ADHD-IN showed similar unique associations with social problems, whereas ADHD-IN was more strongly related than SCT to grades. Across source analyses also supported the differential unique associations of SCT and ADHD-IN with internalizing and externalizing psychopathologies. This study provides initial evidence for the internal and external validity of SCT with South Korean adolescents, extending support for the transcultural validity of SCT to the important developmental period of adolescence.