Associations between psychiatric comorbid disorders and executive dysfunctions in hypocretin-1 deficient pediatric narcolepsy type1.

OBJECTIVE/BACKGROUND: Psychiatric symptoms and cognitive deficits add significantly to impairment in academic achievement and quality of life in patients with narcolepsy. The primary aim of this study was to evaluate the prevalence of psychiatric disorders and executive dysfunctions, secondly to explore the association between psychiatric comorbidity, executive dysfunctions, subjective and objective sleep measures, and severity of cerebrospinal fluid (CSF) hypocretin-1 deficiency in pediatric narcolepsy type 1 (PNT1). PATIENTS/METHODS: Cross-sectional study of 59 consecutively included PNT1 patients (age: 6-20 years; 34:25 girls: boys; 54/59 H1N1 (Pandemrix®)-vaccinated). Core narcolepsy symptoms including subjective sleepiness, polysomnography and multiple sleep latency test results, CSF hypocretin-1 levels, psychiatric disorders (by semistructured diagnostic interview Kaufmann Schedule for Affective Disorders and Schizophrenia Present and Lifetime version (KSADS)), and executive dysfunction (by Behavior Rating of Executive Function (BRIEF)) were assessed. RESULTS: 52.5% of the patients had one or more psychiatric comorbid disorder, and 64.7% had executive dysfunction in a clinically relevant range, with no sex difference in prevalence, while older age was associated with poorer executive function (p=0.013). Having any psychiatric comorbid disorder was associated with poorer executive functions (p=0.001). CSF hypocretin-1 deficiency severity was significantly associated with presence of psychiatric comorbidity (p=0.022) and poorer executive functions (p=0.030), and poorer executive functions was associated with subjective sleepiness (p=0.009). CONCLUSIONS: The high occurrence of, and association between, psychiatric comorbidity and executive dysfunction underlines the importance of close attention to both these comorbidities in clinical care of NT1.

Association Between Prescribed Hypnotics in Infants and Toddlers and Later ADHD: A Large Cohort Study from Norway.

As previously indicated an association may exist between early sleep problems in infants and toddlers, and a diagnosis of attention deficit hyperactivity disorder (ADHD). The aim of this study was to study if this association could be replicated in a complete nationwide cohort of children. Prospective cohort study using national registries. All children born in Norway from January 2004 to December 2010 were included (N = 410,555). Information on hypnotic drugs dispensed to children 0-3 years of age outside of institutions was collected from the Norwegian Prescription Database and used as a proxy for sleep problems. The outcome ADHD (ICD-10), as diagnosed by specialists in the Child Mental Health Service, was obtained from the Norwegian Patient Registry. Data were analysed using weighted estimation in Cox regression. The unadjusted weighted hazard ratio (wHR) for a later diagnosis of ADHD in children dispensed two or more prescriptions for any hypnotic drug, compared to zero prescriptions, was 2.30 [95% confidence interval (CI) 1.63-3.23] for girls and 1.75 (95% CI 1.48-2.07) for boys. For the sedative antihistamine trimeprazine the corresponding wHR was 3.71 (95% CI 1.83-7.52) for girls and 2.78 (95% CI 2.04-3.80) for boys. After adjusting for parental ADHD and parental education the wHR for trimeprazine users was 2.81 (95% CI 1.34-5.88) for girls and 2.33 (95% CI 1.70-3.20) for boys. Infants and toddlers who were dispensed hypnotics had an increased risk of ADHD at school age. This association was most pronounced with the use of trimeprazine, a drug traditionally prescribed to toddlers for sleep problems in Norway. After adjusting for parental ADHD and educational level the risk for ADHD among the trimeprazine users was still more than twice the risk among controls.

High prevalence of ADHD symptoms in unmedicated youths with post-H1N1 narcolepsy type 1.

OBJECTIVES: To characterize attention deficit-hyperactivity disorder (ADHD) symptoms in unmedicated post-H1N1 narcolepsy type 1 (NT1) youths, and explore associations between ADHD symptoms and the narcolepsy phenotype. METHODS: A total of 50 consecutively enrolled post-H1N1 NT1 youths (7-20 years, 62% females, 98% HLA-DQB1∗06:02-positive, 98% CSF hypocretin-1 deficient, 88% vaccinated) were assessed after two weeks off medication for ADHD (ADHD diagnosis pre/post-narcolepsy, parent-rated ADHD symptoms) and narcolepsy-phenotyped (semi-structured interview, Stanford Sleep Questionnaire, Epworth Sleepiness Scale, polysomnography (PSG), Multiple Sleep Latency Test (MSLT)). RESULTS: In sum, 26 (52%) and 15 (30%) of participants had ADHD symptoms above and below the clinical significant cut-off, respectively, while 9 (18%) had no ADHD symptoms. High values were found for ADHD total score (mean (SD), 17.9 (9.5)) and ADHD subscores (inattentive score, 11.0 (6.3); hyperactive/impulsivity score, 6.9 (4.7)). These were significantly higher than previously reported in a mainly medicated narcolepsy cohort (p < 0.0001). Age, gender and disease duration did not influence scores. Two participants (4%) had ADHD diagnosis prior to narcolepsy onset. ADHD symptoms were correlated with parent-rated, but not with patient rated ESS scores, objective sleepiness (mean sleep latency), sleep fragmentation (sleep stage shift index, awakening index), or CSF hypocretin-1 level. CONCLUSION: Comorbid ADHD symptoms were more prevalent in unmedicated post-H1N1 NT1 youths than previously reported in mainly medicated pediatric narcolepsy cohorts. The high prevalence was not due to pre-existing ADHD and generally not correlated with core narcolepsy sleep/wake phenotype characteristics, indicating that the ADHD symptoms were not a direct consequence of disturbed sleep or daytime sleepiness.

The Use of Sleep Medication in Youth Residential Care.

Objectives: To investigate the use of sleep medication and concomitant psychotropic medication in children and adolescents placed under residential care (RC). Methods: Participants were youth 0-20 years of age placed in RC institutions at least once during 2016. Data on filled prescriptions were taken from the Norwegian Prescription Database to compare the use of sleep medication in RC with the general child population (GenPop) and how it covaried with gender, age, reasons for RC placement, and concomitant use of other psychotropic medications (antidepressants, anxiolytics, antipsychotics, and psychostimulants). Results: A total of 2171 youths were identified in RC at mean age 14 years (82% ≥ 13 years). Seventeen percent (371/2171) used sleep medications (melatonin 11%, alimemazine 7%, and benzodiazepines/z-hypnotics 2%) significantly more than the 2.3% who used in GenPop. The girl/boy ratio for medication use in RC was 1.8 (95% confidence interval [CI] = 1.5-2.2), not significantly different from the corresponding ratio in GenPop (1.4; 95% CI = 1.3-1.5). The use of sleep medication increased with age. When comparing reasons for placement in RC, medication use was particularly low among unaccompanied minor asylum seekers (2%). About half of the youths used concomitant psychotropic medication, with clear gender differences; girls used about twice as much antidepressants, anxiolytics, and antipsychotics, whereas boys used 1.3 times more psychostimulants. Conclusion: Youths in RC used more sleep medication and concomitant psychotropic medication than the GenPop, most likely reflecting the increased psychosocial strain and mental disorders reported in this population. Further studies of prevalence, assessment, and treatment of sleep problems in RC populations are warranted.

Psychiatric symptoms in patients with post-H1N1 narcolepsy type 1 in Norway.

STUDY OBJECTIVES: Several studies have reported psychiatric comorbidity in patients with narcolepsy type 1 (NC1). The primary aim of this study was to explore the extent of psychiatric symptoms in a cohort of Norwegian NC1 patients, most of whom were H1N1-vaccinated. We also wanted to explore possible causes of the psychiatric symptoms seen in NC1. METHODS: Cross-sectional study. Psychiatric symptoms were assessed by the Achenbach System of Empirically Based Assessment (ASEBA) Child Behavior Check List (CBCL) in children and by Adult Self Report (ASR) in adults. RESULTS: The mean (SD) total T-scores were 58.6 (9.2) for children and 57.0 (9.8) for adults, these being mainly driven by internalizing problems. Internalizing symptom T-scores showed that 37.5% of the children and 33.3% of the adults were in the clinical range of concern. T-scores were lower when the questionnaire's sleep-related items were excluded. However, 27.5% of children and 22.2% of adults still remained within the total psychiatric symptoms clinical range. Psychiatric symptoms and excessive daytime sleepiness were not associated. However, in children fragmented sleep, measured by sleep-stage shift index was significantly negatively associated with all the psychiatric summary scores (all p ≤ 0.020), and awakening index was negatively associated with externalizing (p = 0.042) and total summary scores (p = 0.042). In adults, awakening index, but not sleep-stage shift index, was positively associated with internalizing score (p = 0.015). Hypocretin-1 levels showed no association with psychiatric symptoms. CONCLUSIONS: We found a high prevalence of psychiatric symptoms in NC1 patients. Fragmented sleep was significantly associated with psychiatric symptoms.

Changes in quality of life in individuals with narcolepsy type 1 after the H1N1-influenza epidemic and vaccination campaign in Norway: a two-year prospective cohort study.

OBJECTIVE: Cross-sectional studies show a lower health-related quality of life (HRQoL) in individuals with narcolepsy. We aimed to describe changes in HRQoL after two years of multidisciplinary follow-up in a cohort of mainly post-H1N1 vaccination narcolepsy type-1 (NT1) patients in Norway. METHODS: Prospective-cohort study. Narcolepsy diagnosis was based on the International Classification of Sleep Disorders (third edition). Psychiatric comorbidity was assessed using the Achenbach System of Empirically Based Assessment (ASEBA). HRQoL was evaluated with the Pediatric Quality of Life Inventory (PedsQL™ Generic Core Scales 4.0) at baseline and follow-up. Mean follow-up time was 20.7 (2.7) months. RESULTS: Thirty one patients (18 females) with NT1, mean age 14.6 (SD = 4.8) years answered questionnaires at baseline and follow-up. On a group level, the PedsQL Total Health Summary score significantly improved by a mean of 5.9 (95%CI = 0.4, 11.9), p = 0.038; this was mainly driven by improvements in the Physical Health Summary score by 9.8 (3.0, 16.5) points, p = 0.006 and the School Functioning Scale score by 7.5 (1.0, 13.9) points p = 0.025. The Total ASEBA score was correlated with PedsQL Total Health Summary score at baseline, but not with changes in HRQoL. Sodium oxybate (Xyrem®) treatment at follow up was positively associated with changes in PedsQL Total Health Summary score, after adjusting for age and gender, p = 0.027. CONCLUSION: HRQoL in NT1 patients improved after two years of follow-up. The use of sodium oxybate (Xyrem®) at follow-up was associated with increases in HRQoL. Psychiatric comorbidity was correlated with HRQoL at baseline but did not predict changes in HRQoL at follow-up.

Neurodevelopmental disorders: prevalence and comorbidity in children referred to mental health services.

BACKGROUND: Accurate prevalence rates of the neurodevelopmental disorders (ND) and comorbid conditions in child and adolescent mental health services (CAMHS) are essential for treatment planning and organization of health care. However, valid and reliable prevalence estimates from Nordic CAMHS populations are scarce, and the published findings vary. AIMS: To report prevalence rates of ND (attention-deficit hyperactivity disorder: ADHD, tic disorder: TD or autism spectrum disorder: ASD) and comorbid disorders by a validated diagnostic instrument in children referred to CAMHS outpatient clinics. METHODS: Parents of 407 consecutively referred children aged 7-13 years were interviewed with the semistructured interview schedule for affective disorders and schizophrenia, present and lifetime version (Kiddie-SADS-PL) at time of admittance. RESULTS: One or more ND was diagnosed in 226 children (55.5%; 69.9% boys): ADHD (44.5%; 68.5% boys); TD (17.7%; 77.8% boys) and ASD (6.1%; 76% boys). Among children with ND 70 (31.0%) had only one ND with no comorbid disorder, 49 (21.7%) had more than one ND (homotypic comorbidity) and 131 (58%) had a non-ND psychiatric disorder (heterotypic comorbidity). Anxiety disorders were the most frequently occurring heterotypic comorbidity in all three ND. Comorbid depressive disorder was associated with older age, and comorbid anxiety disorder with female gender. CONCLUSION: In children referred to CAMHS, ND constitute the most frequently occurring group of disorders, with high rates of both homotypic and heterotypic comorbidity. This needs to be taken into consideration in health service planning and treatment delivery.

Sleep problems in children and adolescents with epilepsy: Associations with psychiatric comorbidity.

Sleep problems are common in pediatric epilepsy and may influence seizure control, daytime functioning, and overall quality of life. Knowledge of factors contributing to sleep problems is likely to improve treatment. The aim of this study was to investigate associations between psychiatric comorbidity and parent-reported and self-reported sleep problems in a sample of children and adolescents with epilepsy. Participants were children and adolescents (N=94), aged 10-19years, with generalized or focal epilepsy who had been referred to a tertiary epilepsy treatment center in Norway. Participants underwent a thorough clinical assessment and 24h of EEG registration. Information on sleep problems was obtained from parents using the Children's Sleep Habit Questionnaire (CSHQ) and from self-reporting using the Sleep Self-Report (SSR) questionnaire. Psychiatric diagnoses were established using the semistructured psychiatric interview Schedule for Affective Disorders and Schizophrenia - Present and Lifetime Version (Kiddie-SADS-PL). Both the total and subdomain CSHQ and SSR scores were high in comparison with scores from population-based samples. Having one or more psychiatric disorder(s) was significantly associated with elevated scores on both the CSHQ and the SSR. With the exception of parent-reported parasomnias, associations between sleep problems and psychiatric disorders remained significant after adjusting for relevant epilepsy variables. Psychiatric comorbidity explained about one-third of the variance of the reported sleep problems in children and adolescents with epilepsy.

Psychiatric comorbidity in children and youth with epilepsy: An association with executive dysfunction?

OBJECTIVES: Psychopathology in children and youth with epilepsy has previously been related to executive dysfunction, but the nature of the association is uncertain. We sought to explore risk factors for psychiatric disorders in children and youth with epilepsy, with emphasis on executive dysfunction, along with seizure-related and psychosocial factors. METHODS: The cohort consisted of one hundred and one consecutive patients aged 10-19 years with focal (n=52) or genetic generalized (n=49) epilepsy. All were screened for psychiatric symptoms, using part of an extensive questionnaire, the Strengths and Difficulties Questionnaire (SDQ) for both patients and their parents. Participants scoring in the borderline or abnormal range on the SDQ received a psychiatric interview (Kiddie-SADS-PL). All participants underwent a neuropsychological examination, and those with general cognitive abilities (IQ)<70 were excluded. RESULTS: Forty-seven of 101 participants (46.5%) had a SDQ score in the borderline or abnormal range and underwent a psychiatric evaluation. Of these, 44 (93.6%) met the criteria for a psychiatric diagnosis, the most common being ADHD and anxiety. An executive deficit was identified in 26.8% of the participants with a psychiatric diagnosis, but in only 5.4% of those without such a diagnosis (p=0.003). Multivariate logistic regression analysis showed that executive dysfunction was an independent risk factor for having a psychiatric disorder (OR 8.2, CI 1.8-37.2, p=0.006), along with male gender (OR 2.9, CI 1.2-7.3, p=0.02), and early seizure onset (0.86-that is one year older equals risk of psychiatric disorder reduced by 14%-CI 0.77-0.96, p=0.01). Other epilepsy-related or psychosocial factors were not significantly associated with psychiatric disorders. CONCLUSIONS: Multiple factors are associated with psychiatric problems in children and youth with epilepsy. In this study, executive dysfunction, male gender, and early epilepsy onset were independent risk factors for having a psychiatric disorder. An evaluation of psychiatric and cognitive problems is important to enable a positive long-term outcome in childhood epilepsy.

Convergent and divergent validity of K-SADS-PL anxiety and attention deficit hyperactivity disorder diagnoses in a clinical sample of school-aged children.

Background The Schedule for Affective Disorders and Schizophrenia for School Age Children, Present and Lifetime Version (K-SADS-PL) is a commonly used diagnostic interview both in research and clinical settings, yet published data on the psychometric properties of the interview generated diagnoses are scarce. Aims To examine the convergent and divergent validity of the Norwegian version of the K-SADS-PL current diagnoses of anxiety disorders and attention deficit hyperactivity disorder (ADHD). Method Participants were 105 children aged 7-13 years referred for treatment at child mental health clinics and 36 controls. Diagnostic status was determined based on K-SADS-PL interviews with the mothers. Child and mother reported child symptoms of anxiety on the Multidimensional Anxiety Scale for Children and teachers reported anxiety symptoms on the Teacher Report Form. Mother and teacher reported on symptoms of ADHD on the Disruptive Behavior Rating Scale. Results Rating scale data from multiple informants in a clinical sample and healthy controls supported the convergent and divergent validity of K-SADS-PL anxiety diagnoses combined, and, specifically, the diagnoses of separation anxiety disorder, social phobia, and specific phobia. Support was also observed for convergent and divergent validity of ADHD diagnoses, including the predominately inattentive subtype. Conclusion The K-SADS-PL generates valid diagnoses of anxiety disorders and ADHD.

Non-obsessive-compulsive anxiety disorders in child and adolescent mental health services--Are they underdiagnosed, and how accurate is referral information?

BACKGROUND: Previous studies have reported low prevalence of non-obsessive-compulsive (OCD) anxiety disorders in child and adolescent mental health services (CAMHSs), suggesting that these disorders may go unrecognized. Possible reasons may be lack of routinely used standardized diagnostic instruments, and/or an under-reporting of anxiety symptoms in the referral information. AIMS: To examine the frequency of non-OCD anxiety disorders in referred children based on a standardized diagnostic interview, to compare the results with data from the Norwegian Patient Register (NPR), and to explore the correspondence between anxiety as a referral symptom and anxiety as a diagnosis, and the influence of heterotypic co-morbidity on this correspondence. METHODS: Parents of 407 consecutive referrals to CAMHS aged 7-13 years were interviewed with the semi-structured diagnostic interview Kiddie-SADS-PL at the time of admittance. Referral symptoms were collected from national referral forms. RESULTS: A total of 133 referred children (32.7%) met the criteria for a non-OCD anxiety disorder compared with about 5% in the NPR. Half of those who met diagnostic criteria for an anxiety disorder did not have anxiety as a referral symptom. Co-morbid ADHD or disruptive disorder was significantly associated with a lower probability of having anxiety as a referral symptom. CONCLUSIONS: The use of a standardized diagnostic interview in consecutively referred children yielded significantly higher rates of anxiety disorders than the NPR prevalence rates. Co-morbid ADHD or disruptive disorder may contribute to the underdiagnosing of anxiety disorders. Diagnostic instruments covering the whole range of child psychiatric symptoms should be implemented routinely in CAMHS.

Somatic symptoms in children with anxiety disorders: an exploratory cross-sectional study of the relationship between subjective and objective measures.

Symptoms of childhood anxiety disorders include activation of bodily stress systems to fear stimuli, indicating alterations of the autonomic nervous system (ANS). Self-reported somatic symptoms are frequently reported, while studies including objective measures of ANS are scarce and show inconsistent results. Even less studied is the relationship between subjective and objective measures of somatic symptoms in anxious children. Increased knowledge of this relationship may have relevance for treatment programmes for anxiety disorders. This cross-sectional study examined subjective and objective measures of ANS responsiveness in a clinical sample of children with anxiety disorders (7-13 years; n = 23) and in healthy controls (HC; n = 22) with equal distributions of gender and age. The subjective measure used was the Multidimensional Anxiety Scale for Children, which includes a subscale on somatic symptoms. The objective measures consisted of an orthostatic challenge (head-up tilt test), and an isometric muscular exercise (handgrip) while the participants were attached to the Task Force Monitor, a combined hardware and software device used for continuous, non-invasive recording of cardiovascular variables. The anxiety disorder group reported significantly more somatic symptoms than HCs (both by mother and child reports). In contrast, no relevant differences in cardiovascular variables were demonstrated between the anxiety group and HCs. Finally, there were no significant correlations between subjective and objective measures in either group. Because of the small sample size, the findings must be interpreted carefully, but the results do not support previous reports of functional alterations of the ANS in anxious children.

Associations between sleep problems and attentional and behavioral functioning in children with anxiety disorders and ADHD.

This study examined associations between sleep problems and attentional and behavioral functioning in 137 children aged 7 to 13 years with anxiety disorders (n = 39), attention deficit hyperactivity disorder (ADHD; n = 38), combined anxiety disorder and ADHD (n = 25), and 35 controls. Diagnoses were made using the semistructured diagnostic interview Schedule for Affective Disorders and Schizophrenia for School-age Children-Present and Lifetime Version. Sleep problems were assessed using the Children's Sleep Habits Questionnaire, attention was measured by the Attention Network Test, and behavioral problems were measured by teacher ratings on the Achenbach System of Empirically Based Assessment, Teacher Report Form. Sleep problems were associated with reduced efficiency of the alerting attention system for all children and with increased internalizing problems in children with anxiety disorders.

Persistence of sleep problems in children with anxiety and attention deficit hyperactivity disorders.

This study examines the persistence of sleep problems over 18 months in 76 referred children with anxiety disorders and/or attention deficit hyperactivity disorders (ADHD) and 31 nonreferred controls, and explores predictors of sleep problems at follow-up (T2) in the referred children. Diagnoses were assessed at initial assessment (T1) using the semi-structured interview Kaufman Schedule for Affective Disorders and Schizophrenia. Sleep problems were assessed using the Children's Sleep Habit Questionnaire at T1 and at T2. Persistence rate of total sleep problems in the clinical range was 72.4 % in referred children, and did not differ significantly between children with a T1 diagnosis of anxiety disorder (76.0 %), ADHD (70.6 %), anxiety disorder and ADHD (68.8 %) or nonreferred controls (50.0 %) The total sleep problems score at T1 significantly predicted the total sleep problems score at T2, whereas age, sex, parent education level and total number of life events did not.

Motor impairment in children with anxiety disorders.

This study examined the frequency and degree of motor impairment in referred children with anxiety disorders (AnxDs), compared with children with attention deficit/hyperactivity disorder (ADHD), children with comorbid AnxDs and ADHD, and nonreferred controls. All participants (n=141; 90 males, 51 females; mean age: 10 years, 1 month; range: 7-13 years) had an IQ greater than 70. Diagnoses of mental disorders were established using the Schedule for Affective Disorders and Schizophrenia for School-Aged Children (Kiddie-SADS). Motor ability was assessed using the Movement Assessment Battery for Children (M-ABC). We found that children with AnxDs exhibited significantly higher total impairment scores on the M-ABC than controls, but were not significantly different from children with ADHD or children with comorbid AnxDs and ADHD. All clinical groups exhibited similar profiles of motor impairment. A total of 19 (46%) children with AnxDs scored below the 5th percentile on the M-ABC, indicating that motor function is impaired in many children with AnxDs to a degree that probably interferes with their activities of daily living. These results support the notion that assessment of motor function is important in understanding the daily challenges of children with AnxDs.

Comparison of sleep problems in children with anxiety and attention deficit/hyperactivity disorders.

This cross-sectional case-control study compared sleep problems in consecutively referred children aged 7-13 years meeting DSM-IV criteria for anxiety disorder, attention deficit/hyperactivity disorder (ADHD), comorbid anxiety disorder and ADHD, and a group of control children of similar age and gender. Diagnoses were assessed with the Kiddie-SADS PL interview, parent form, and the sleep problems with a standardized sleep questionnaire, the Children's Sleep Habits Questionnaire (CSHQ), as reported by the mother. A total of 141 children were included (anxiety disorder (n = 41), ADHD (n = 39), comorbid condition (n = 25), controls (n = 36)). Children in the clinical groups had more sleep problems than controls. Children with anxiety disorders and children with comorbid condition were reported to have more sleep problems than children with ADHD alone. Night waking was associated with comorbid anxiety disorder and ADHD. Bedtime resistance was associated with anxiety disorder, while daytime sleepiness affected all clinical groups. Clinical management of children with ADHD and anxiety disorders needs to include assessment of sleep problems.

The relationship between sluggish cognitive tempo, subtypes of attention-deficit/hyperactivity disorder, and anxiety disorders.

The objective of the present study was to examine the relationship between sluggish cognitive tempo (SCT), subtypes of attention-deficit/hyperactivity disorder (ADHD), and anxiety disorders (AnxDs). One hundred and forty-one children (90 males, 51 females) aged 7-13 years were assigned to four groups, i.e., referred children with comorbid AnxDs and ADHD (n = 25), ADHD (n = 39), AnxDs (n = 41), and nonreferred controls (n = 36). Furthermore we explored the association between SCT and several neurocognitive measures (reaction time, verbal memory, and spatial memory). Diagnoses were established using Kiddie-SADS P/L. SCT was assessed using a 17-item mother-reported questionnaire. SCT correlated significantly with inattentiveness, regardless of the subtype of ADHD. Furthermore, we found significant differences in the levels of SCT among the four groups, with the highest SCT scores observed in the comorbid group. SCT correlated with variability in spatial memory; in contrast, there was no correlation between SCT and reaction time.