Endophenotypes for intelligence in children and adolescents

Test-retest reliability for common tasks in vision science

Research in perception and attention has typically sought to evaluate cognitive mechanisms according to the average response to a manipulation. Recently, there has been a shift toward appreciating the value of individual differences and the insight gained by exploring the impacts of between-participant variation on human cognition. However, a recent study suggests that many robust, well-established cognitive control tasks suffer from surprisingly low levels of test-retest reliability (Hedge, Powell, & Sumner, 2018b). We tested a large sample of undergraduate students (n = 160) in two sessions (separated by 1–3 weeks) on four commonly used tasks in vision science. We implemented measures that spanned a range of perceptual and attentional processes, including motion coherence (MoCo), useful field of view (UFOV), multiple-object tracking (MOT), and visual working memory (VWM). Intraclass correlations ranged from good to poor, suggesting that some task measures are more suitable for assessing individual differences than others. VWM capacity (intraclass correlation coefficient [ICC] = 0.77), MoCo threshold (ICC = 0.60), UFOV middle accuracy (ICC = 0.60), and UFOV outer accuracy (ICC = 0.74) showed good-to-excellent reliability. Other measures, namely the maximum number of items tracked in MOT (ICC = 0.41) and UFOV number accuracy (ICC = 0.48), showed moderate reliability; the MOT threshold (ICC = 0.36) and UFOV inner accuracy (ICC = 0.30) showed poor reliability. In this paper, we present these results alongside a summary of reliabilities estimated previously for other vision science tasks. We then offer useful recommendations for evaluating test-retest reliability when considering a task for use in evaluating individual differences.

The Negative Impact of Noise on Adolescents' Executive Function: An Online Study in the Context of Home-Learning During a Pandemic

UNICEF estimates that 1.6 billion children across the world have had their education impacted by COVID-19 and have attempted to continue their learning at home. With ample evidence showing a negative impact of noise on academic achievement within schools, the current pre-registered study set out to determine what aspects of the home environment might be affecting these students. Adolescents aged 11-18 took part online, with 129 adolescents included after passing a headphone screening task. They filled out a sociodemographic questionnaire, followed by a home environment and noise questionnaire. Participants then completed three executive function tasks (the Flanker, the Backward Digit Span, and the Wisconsin Card Sorting Test) while listening to a soundtrack of either white noise or home-like environmental noise. For purposes of analysis, based on the noise questionnaire, participants were separated into quieter and noisier homes. Results revealed that measures of the home environment significantly correlated with individual perceptions of noise and task performance. In particular, adolescents coming from noisier homes were more likely to report that they studied in a noisy room and that they were annoyed by noise when studying. In terms of noise and task performance, the Flanker task revealed that while older adolescents were more efficient overall than their younger peers, those older adolescents from noisier homes seemed to lose this advantage. Additionally, reaction times for younger adolescents from noisier homes were less impacted by accuracy compared to their peers from quieter homes, though there was no difference for the older adolescents. This evidence suggests that higher in-home noise levels lead to higher rates of annoyance and may be hindering home-learning, with both younger and older adolescents being impacted. Furthermore, the long-term effect of in-home noise on adolescent executive function task performance indicates that these findings transcend the pandemic and would influence in-school learning. Limitations and advantages of online adolescent research without researcher supervision are discussed, including sociodemographics and adapting tasks.

Do effects of methylphenidate on cognitive performance last beyond treatment? A randomized placebo-controlled trial in boys and men with ADHD

Methylphenidate (MPH) is the first-choice pharmacological treatment for treatment of Attention-Deficit/Hyperactivity Disorder (ADHD) across the lifespan. However, it is unclear whether MPH affects cognitive development, while recent (pre-) clinical studies suggest effects on the developing brain. The present randomized, placebo-controlled trial aims to determine whether MPH has short-term, age-dependent effects on cognitive performance in ADHD after a 1-week washout. Effects of 16 weeks MPH treatment were assessed after a one-week washout on cognitive functioning. Boys (age=10-12) and men (age=23-40) with ADHD were assigned to MPH treatment (boys n=25, men n=24) or placebo (boys n=25, men n=24). Outcome measures were working memory, response inhibition, response speed, episodic memory, and delay aversion. Differences in task performances over time (pre-, mid-, and post-treatment, following a 1-week wash-out) were compared between age and treatment conditions with mixed ANOVAs. MPH improved working memory and response speed, but only during treatment. No lasting age*treatment effects were observed post intervention. Overall, the results from the present randomized, placebo-controlled trial show that the effects of MPH on cognition do not extend past treatment in children or adults. While treatment with MPH improves cognition during treatment, these effects appear transient after 16-weeks of treatment. (Title trial: "Effects of methylphenidate on the developing brain"; http://www.trialregister.nl/trialreg/admin/rctview.asp?TC=3103).

Zum Zusammenhang von Arbeitsgedächtnisleistungen und ausgewählten Exekutivfunktionen bei Kindern mit ADHS

Zusammenfassung. Defizite in Exekutivfunktionen werden als ein wesentliches Merkmal einer Aufmerksamkeitsdefizit-/Hyperaktivitätsstörung angesehen. Bisher liegen wenige standardisierte Testverfahren zur Erfassung solcher exekutiven Defizite vor, die bei Kindern und Jugendlichen besonders eng mit einer ADHS assoziiert scheinen (kognitive Flexibilität, Inhibition, Handlungsplanung, „Switching“). Das Hauptziel der vorliegenden Studie war deshalb die Validierung des neuropsychologischen Moduls des ADHS-Diagnostikums für Kinder und Jugendliche (ADHS-KJ-NPT). Diesbezüglich wurde eine Stichprobe von 58 ADHS-Kindern (77.6 % männlich) im Alter von 6 bis 12 Jahren ( M = 9.01 Jahre; SD = 1.43) mit dem ADHS-KJ-NPT sowie mit den Untertests des Index Arbeitsgedächtnis und des Index Verarbeitungsgeschwindigkeit des Wechsler-Intelligenztests (WISC-V) untersucht. Die Ergebnisse zeigen, dass die ADHS-KJ-NPT-Untertests, die darauf abzielen, Defizite in der Inhibitionsfähigkeit zu erfassen, mit dem WISC-V-Index Arbeitsgedächtnis korrelieren. Zudem wurden Korrelationen zwischen dem WISC-V-Index Verarbeitungsgeschwindigkeit und den ADHS-KJ-NPT-Untertests gefunden, mit denen Defizite in der flexiblen Aufmerksamkeitssteuerung und in der Inhibitionsfähigkeit auf äußere Reize erfasst werden sollen. Diese Korrelationen stellten sich bei 6- bis 9-jährigen Kindern als substanziell heraus, während dies bei 10- bis 12-Jährigen nicht der Fall ist. Die Studie trägt weiter zur Fundierung der Kriteriumsvalidität des neuropsychologischen Moduls des ADHS-KJ bei.

What Does the n-Back Task Measure as We Get Older? Relations Between Working-Memory Measures and Other Cognitive Functions Across the Lifespan

Working memory (WM) declines with increasing age. The WM capacity is often measured by means of the computerized version of the n-back task. Although the n-back task is widely used in aging research, little is known about its construct validity and specific cognitive functions involved in this task. Moreover, to date, no studies analyzed the construct validity as a function of age. To this end, we conducted a study in a sample of N = 533 individuals aged between 20 and 80 years. The sample was divided into three age groups: young (20-40), middle-aged (41-60), and old (61-80 years). A number of psychometric tests was selected that measure attention, memory, and executive control to elucidate the impact of these constructs on n-back performance. A series of correlation analyses was conducted to assess the relationship between n-back performance and specific cognitive functions in each age group separately. The results show a progressive increase in reaction times and a decrease in the proportion of detected targets from young to old subjects. Age-related impairments were also found in all psychometric tests except for the vocabulary choice test measuring crystallized intelligence. Most importantly, correlations yielded different age-related patterns of functions contributing to performance in the n-back task: whereas performance was most related to executive functions in young age, a combination of attentional and executive processes was associated with performance in middle-aged subjects. In contrast, in older age, mainly attentional, verbal memory, and updating and to a lesser extent executive processes seem to play a crucial role in the n-back task, suggesting a shift of processing strategies across the lifespan.

Fitness, Sleep-Disordered Breathing, Symptoms of Depression, and Cognition in Inactive Overweight Children: Mediation Models

OBJECTIVES

We used mediation models to examine the mechanisms underlying the relationships among physical fitness, sleep-disordered breathing (SDB), symptoms of depression, and cognitive functioning.

METHODS

We conducted a cross-sectional secondary analysis of the cohorts involved in the 2003-2006 project PLAY (a trial of the effects of aerobic exercise on health and cognition) and the 2008-2011 SMART study (a trial of the effects of exercise on cognition). A total of 397 inactive overweight children aged 7-11 received a fitness test, standardized cognitive test (Cognitive Assessment System, yielding Planning, Attention, Simultaneous, Successive, and Full Scale scores), and depression questionnaire. Parents completed a Pediatric Sleep Questionnaire. We used bootstrapped mediation analyses to test whether SDB mediated the relationship between fitness and depression and whether SDB and depression mediated the relationship between fitness and cognition.

RESULTS

Fitness was negatively associated with depression ( B = -0.041; 95% CI, -0.06 to -0.02) and SDB ( B = -0.005; 95% CI, -0.01 to -0.001). SDB was positively associated with depression ( B = 0.99; 95% CI, 0.32 to 1.67) after controlling for fitness. The relationship between fitness and depression was mediated by SDB (indirect effect = -0.005; 95% CI, -0.01 to -0.0004). The relationship between fitness and the attention component of cognition was independently mediated by SDB (indirect effect = 0.058; 95% CI, 0.004 to 0.13) and depression (indirect effect = -0.071; 95% CI, -0.01 to -0.17).

CONCLUSIONS

SDB mediates the relationship between fitness and depression, and SDB and depression separately mediate the relationship between fitness and the attention component of cognition.

Normative data on the n-back task for children and young adolescents

The n-back task is a frequently used measure of working memory (WM) in cognitive neuroscience research contexts, and it has become widely adopted in other areas over the last decade. This study aimed to obtain normative data for the n-back task from a large sample of children and adolescents. To this end, a computerized verbal n-back task with three levels of WM load (1-back, 2-back, and 3-back) was administered to 3722 Spanish school children aged 7–13 years. Results showed an overall age-related increase in performance for the different levels of difficulty. This trend was less pronounced at 1-back than at 2-back when hits were considered. Gender differences were also observed, with girls outperforming boys although taking more time to respond. The theoretical implications of these results are discussed. Normative data stratified by age and gender for the three WM load levels are provided.

Clinical utility of the N-back task in functional neuroimaging studies of working memory

INTRODUCTION

N-back tasks are commonly used in functional neuroimaging studies to identify the neural mechanisms supporting working memory (WM). Despite widespread use, the clinical utility of these tasks is not well specified. This study compared N-back performance during functional magnetic resonance imaging (fMRI) with task data acquired outside of the scanner as a measure of reliability across environment. N-back task validity was examined in relation to performance and rater-based measures used clinically to assess working memory.

METHOD

Forty-three healthy adults completed verbal and object N-back tasks during fMRI scanning and outside the scanner. Task difficulty was varied parametrically (0, 1, and 2-back conditions). Order of N-back task completion was stratified by modality (verbal/object) and environment. Participants completed the Digit Span (DS) and provided self-ratings using the Behavior Rating Inventory of Executive Function (BRIEF-WM).

RESULTS

Mean verbal and object N-back accuracy was above 95% across load conditions; task difficulty was effectively manipulated across load conditions. Performance accuracy did not significantly differ by environment. N-back reaction time was slower during fMRI (F = 6.52, p = .01, ηp(2) = .13); participants were faster when initially completing tasks outside the scanner (ηp(2) = .10-.15). Verbal 2-back accuracy was significantly related to DS performance (r = .36, p = .02). N-back performance was not related to BRIEF-WM.

CONCLUSIONS

Our results provide evidence for reliability of N-back accuracy during fMRI scanning; however, reliability of reaction time data is affected by order of task presentation. Data regarding construct validity are inconsistent and emphasize the need to consider clinical utility of behavioral measures in the design and interpretation of functional neuroimaging studies.

Interference control in adolescents with mild-to-borderline intellectual disabilities and/or behavior disorders

The aim of this study was to investigate interference control in adolescents with Mild to Borderline Intellectual Disability (MBID) by addressing two key questions. First, as MBID is often associated with comorbid behavior disorders (BD), we investigated whether MBID and BD both affect interference control. Second, we studied whether interference control deficits are associated to problems in everyday executive functioning. Four groups of adolescents with and without MBID and/or BD performed the Eriksen flanker task, requiring participants to respond to a central target while ignoring interfering flanking stimuli. Their teachers rated behavior on the Behavior Rating Inventory Executive Function (BRIEF). We found pronounced effects of MBID but not BD on flanker interference control. In contrast, we observed pronounced effects of BD, but not MBID, on the BRIEF. In addition, flanker interference scores and BRIEF scores did not correlate. These results are taken to suggest that adolescents with MBID are characterized by deficits in interference control that do not become manifest in ratings of everyday executive functioning. In contrast, adolescents with BD are not characterized by deficits in interference control but do show elevated ratings of deficits in everyday executive function.

Lexical decision as an endophenotype for reading comprehension: an exploration of an association

Based on numerous suggestions in the literature, we evaluated lexical decision (LD) as a putative endophenotype for reading comprehension by investigating heritability estimates and segregation analyses parameter estimates for both of these phenotypes. Specifically, in a segregation analysis of a large sample of families, we established that there is little to no overlap between genes contributing to LD and reading comprehension and that the genetic mechanism behind LD derived from this analysis appears to be more complex than that for reading comprehension. We conclude that in our sample, LD is not a good candidate as an endophenotype for reading comprehension, despite previous suggestions from the literature. Based on this conclusion, we discuss the role and benefit of the endophenotype approach in studies of complex human cognitive functions.

An examination of the relationship between motor coordination and executive functions in adolescents

AIM

Research suggests important links between motor coordination and executive functions. The current study examined whether motor coordination predicts working memory, inhibition, and switching performance, extending previous research by accounting for attention-deficit-hyperactivity disorder (ADHD) symptomatology and other confounding factors, in an adolescent normative sample.

METHOD

Ninety-three adolescents (38 females, 55 males) aged 12 to 16 years (mean age 4y 2mo, SD 1y 1mo) were assessed on the Movement Assessment Battery for Children-2 (MABC-2), Wechsler Intelligence Scale for Children-IV, N-back task, the inhibition subtest from the NEPSY-II: A Developmental Neuropsychological Assessment, second edition, and the parent-rated Strengths and Weaknesses of ADHD Symptoms and Normal Behaviour Questionnaire.

RESULTS

The MABC-2 total score accounted for a significant proportion of the variance in visuospatial working memory (p=0.041) but not for verbal working memory. The MABC-2 aiming and catching component, however, was found to account for unique variance in both verbal (p=0.019) and visuospatial working memory (p=0.016). The MABC-2 total score was found to account for a significant proportion of the variance in inhibition total completion time (p=0.017). Finally, balance skills accounted for unique variance in a NEPSY-II inhibition total errors variable (p=0.020).

INTERPRETATION

The results provide support for an overlap between motor coordination and executive functions, which has important practical implications. The study also suggests shared mechanisms underpinning the relationship between these areas, including possible cerebellar involvement.

Brain SCALE: brain structure and cognition: an adolescent longitudinal twin study into the genetic etiology of individual differences

From childhood into adolescence, the child's brain undergoes considerable changes in both structure and function. Twin studies are of great value to explore to what extent genetic and environmental factors explain individual differences in brain development and cognition. In The Netherlands, we initiated a longitudinal study in which twins, their siblings and their parents are assessed at three year intervals. The participants were recruited from The Netherlands Twin Register (NTR) and at baseline consisted of 112 families, with 9-year-old twins and an older sibling. Three years later, 89 families returned for follow-up assessment. Data collection included psychometric IQ tests, a comprehensive neuropsychological testing protocol, and parental and self-ratings of behavioral and emotional problems. Physical maturation was measured through assessment of Tanner stages. Hormonal levels (cortisol, luteinizing hormone, follicle-stimulating hormone, testosterone, and estrogens) were assessed in urine and saliva. Brain scans were acquired using 1.5 Tesla Magnetic Resonance Imaging (MRI), which provided volumetric measures and measures of cortical thickness. Buccal swabs were collected for DNA isolation for future candidate gene and genome-wide analysis studies. This article gives an overview of the study and the main findings. Participants will return for a third assessment when the twins are around 16 years old. Longitudinal twin-sibling studies that map brain development and cognitive function at well-defined ages aid in the understanding of genetic influences on normative brain development.

Neurocognitive deficits in children with sickle cell disease are associated with the severity of anemia

BACKGROUND

Although neurocognitive deficits in children with sickle cell disease (SCD) have been well documented, the etiology of these deficits has not been completely clarified. The aim of this study was to investigate the association of laboratory markers of disease severity and radiological parameters with neurocognitive functioning in children with SCD.

DESIGN AND METHODS

Participants were 37 children with SCD ((HbSS or HbS-β(0)-thalassemia) aged 6-18 years. All participants underwent extensive neurocognitive assessment. Further data (TCD values, laboratory test results, and MRI data) were obtained from medical charts. Associations were analyzed by hierarchical regression analysis.

RESULTS

Hemoglobin was associated with a decrease in verbal short-term memory. There was no association between TCD velocities and neurocognitive functioning, when controlled for age. Children with silent infarcts did not differ from children with normal MRI in neurocognitive functioning. Children with right-left asymmetries in cerebral blood flow as measured by continuous arterial spin labelling (CASL) MRI had better sustained attention than children without asymmetries.

CONCLUSIONS

Neurocognitive deficits are associated with the severity of anemia, indicating reduced oxygen delivery to the brain as an etiological mechanism. This implies that children with SCD and normal MRIs may still suffer from neurocognitive impairments, possibly affecting their academic development and full participation in society.

Neurocognitive deficits in children with sickle cell disease: a comprehensive profile

BACKGROUND

Sickle cell disease (SCD) can lead to profound cerebral damage, associated with neurocognitive deficits. The aim of the current study was to evaluate a broad range of neurocognitive functions in children with SCD compared to a SES-matched control group, in order to gain more insight into the specific deficits of these patients.

METHODS

Forty-one children with homozygous SCD (HbSS or HbS-β0-thalassemia) and 38 controls were assessed on a comprehensive set of well-defined and validated measures of neurocognitive functioning. Besides general intelligence, we evaluated executive functioning extensively (including response inhibition, sustained attention, planning, visuo-spatial working memory, and verbal working memory) as well as visuo-motor functioning.

RESULTS

SCD was clearly associated with lower IQ scores. More than one in three children with SCD had a Full-scale IQ below 75. Furthermore, children with SCD showed deficits in visuo-motor functioning. Some evidence was found for executive dysfunction: Children with SCD displayed poor visuo-spatial working memory, as well as subtle deficits in sustained attention and planning. No significant differences were found between children with SCD and controls in terms of response inhibition and verbal working memory.

CONCLUSIONS

Children with SCD are at increased risk of lower intelligence, visuo-motor impairments, and executive dysfunction. These neurocognitive deficits may underlie high rates of scholastic impairments in these children. The present findings further illuminate the importance of regular neurocognitive evaluations and future neurocognitive rehabilitation programs for children with SCD.