Intraindividual Reaction Time Variability Research Articles

Reaction Time Variability in Children Is Specifically Associated With Attention Problems and Regional White Matter Microstructure

BackgroundIncreased intraindividual variability (IIV) in reaction times (RTs) has been suggested as a key cognitive and behavioral marker of attention problems, but findings for other dimensions of psychopathology are less consistent. Moreover, while studies have linked IIV to brain white matter microstructure, large studies testing the robustness of these associations are needed. MethodsWe used data from the Adolescent Brain Cognitive Development (ABCD) Study baseline assessment to test the associations between IIV and psychopathology (n = 8622, age = 8.9–11.1 years) and IIV and white matter microstructure (n = 7958, age = 8.9–11.1 years). IIV was investigated using an ex-Gaussian distribution analysis of RTs in correct response go trials in the stop signal task. Psychopathology was measured by the Child Behavior Checklist and a bifactor structural equation model was performed to extract a general p factor and specific factors reflecting internalizing, externalizing, and attention problems. To investigate white matter microstructure, fractional anisotropy, mean diffusivity, axial diffusivity, and radial diffusivity were examined in 23 atlas-based tracts. ResultsIncreased IIV in both short and long RTs was positively associated with the specific attention problems factor (Cohen’s d = 0.13 and d = 0.15, respectively). Increased IIV in long RTs was also positively associated with radial diffusivity in the left and right corticospinal tract (both tracts, d = 0.12). ConclusionsUsing a large sample and a data-driven dimensional approach to psychopathology, the results provide novel evidence for a small but specific association between IIV and attention problems in children and support previous findings on the relevance of white matter microstructure for IIV.

Synergistic effects of high early-life stress exposure and HIV infection on reaction time variability.

Addressing comorbidities contributing to cognitive impairment in people living with HIV (PLWH) remains imperative. Prior studies utilizing reaction time intra-individual variability (RT-IIV), a robust behavioral marker of cognitive dysfunction, demonstrate increased cognitive impairment in adults living with HIV who have high early life stress (ELS) exposure relative to those with low-ELS exposure. Yet, it is unknown whether RT-IIV elevations are due to high-ELS alone or both HIV-status and high-ELS. In the current study, we explore the potential additive effects of HIV and high-ELS exposure on RT-IIV to better characterize the independent and combined effects of these factors on RT-IIV among PLWH. We assessed 59 PLWH and 69 HIV-negative healthy control (HC) participants with either low or high ELS on RT-IIV during a working memory task (1-back). We observed a significant interaction between HIV status and ELS exposure on RT-IIV, PLWH who had experienced high ELS demonstrating RT-IIV elevations relative to all other groups. In addition, RT-IIV was significantly associated with ELS exposure in PLWH, but not in the HC group. We also observed associations between RT-IIV and measures of HIV-disease severity (plasma HIV viral load, nadir CD4) among PLWH. Taken as a whole, these findings provide novel evidence of the combined effects of HIV and high-ELS exposure on RT-IIV, and thus suggest HIV-related and ELS-related neural abnormalities may act in an additive or synergistic manner to affect cognition. Such data warrant further investigation into the neurobiological mechanisms associated with HIV and high-ELS exposure that contribute to increased neurocognitive dysfunction among PLWH.

Fluctuations in reaction time performance as a marker of incipient amyloid‐related cognitive decline in clinically unimpaired older adults.

AbstractBackgroundAccumulating evidence suggests that fluctuations in reaction time (RT) performance across assessments, usually defined by intraindividual variability in RT (IIV‐RT), are associated with cognitive impairment and decreased neurobiological integrity. Computerized cognitive testing facilitates the study of IIV‐RT, allowing for precise and frequent RT measurements in remote settings. We investigated whether quantifying IIV‐RT over months on various remotely administered computerized RT tasks could aid in the detection of emerging cognitively decline in initially clinically unimpaired (CU) older adults with elevated Alzheimer’s disease (AD) biomarkers.MethodN = 114 CU individuals (age 77.6±5.1, 61% female, MMSE 29±1.2, n = 33 amyloid‐positive as measured using PiB‐PET imaging) from the Harvard Aging Brain Study (HABS) completed the self‐administered Computerized Cognitive Composite (C3) monthly at‐home on an iPad for up to one year (11.7±3.2 C3 assessments). Baseline C3 assessment coincided with participants’ HABS in‐clinic visit including Preclinical Alzheimer’s Cognitive Composite (PACC) testing, and participants had 1.8±1.2 subsequent years follow‐up PACC testing available. The C3 includes two basic RT tasks (Detection [DET]; Identification [IDN]), and two complex RT tasks (One Card Learning [OCL]; One Back [ONB]) that also require working memory skills. IIV‐RT measures were derived for each task by computing the intraindividual standard deviation between mean RTs across all monthly visits for each participant. Subsequently, IDN and DET IIV‐RT were combined into a basic IIV‐RT composite, and OCL and ONB IIV‐RT into a complex IIV‐RT composite. Linear mixed models were used to investigate the association between both IIV‐RT composites and PACC decline adjusting for covariates (age, sex, education, amyloid status (+/‐)) and their interaction with time.ResultGreater IIV‐RT on complex RT tasks was associated with steeper decline on the PACC (Time*IIV‐RT ß = ‐1.3, 95%CI[‐2.57 – ‐0.03],p = .04) (Figure 1), which was driven by amyloid‐positive individuals (Time*Amyloid[+]*IIV‐RT ß = ‐3.52, 95%CI[‐6.43 – ‐0.61],p = .02) (Figure 2). In contrast, greater IIV‐RT on basic RT tasks was only associated with baseline PACC performance (IIV‐RT ß = ‐4.29, 95%CI[‐7.32 – ‐1.26],p = .007) but not with PACC change over time.ConclusionOur findings suggest that fluctuations in RT performance over monthly‐repeated complex RT tasks may reflect evidence of early amyloid‐related neurodegeneration and provide a marker of incipient cognitive decline in preclinical AD.

Attention deficits in Brazilian health care workers with chronic pain.

The impact of COVID-19 on chronic pain (CP) in non-infected vulnerable South American subjects is unknown. Healthcare workers (HCWs) are at increased risk for CP. During the pandemic, many HCWs with CP kept working. Knowing how cognition is affected by CP in these subjects is an important subject for work safety. The attention domain has a pivotal role in cognition. Previously, the Continuous Visual Attention Test (CVAT) was applied to detect specific attention deficits in fibromyalgia patients. The present investigation described CP prevalence in non-infected Brazilian HCWs during the pandemic and assessed HCWs' attentional performance with the aid of the CVAT. This study was carried out at a reference University Hospital in Rio de Janeiro, Brazil. HCWs of both sexes, aged 20 or older, were interviewed from August to December 2020. A 90-second version of the CVAT was performed. The average reaction time to correct responses and the respective intraindividual reaction time variability for correct responses to target (VRT) was determined. Omission and commission errors were also calculated. Then, for each participant we calculated the Z-scores of the CVAT variables based on the distribution of CVAT performance of 211 healthy subjects (reference-comparison group). HCWs with Z-scores > 1.64 were classified as significantly impaired. From the 154 selected HCWs, 72 reported CP during the pandemic (prevalence = 47%). Post hoc ANCOVAs showed that the average correct VRT was significantly higher in the CP group than in the non-CP group (F = 4.99, df = 1/150, p = 0.027, η2 = 0.032). The percentage of participants with impaired VRT performance was 30% (n = 21) in the CP group and 16% (n = 13) in the non-CP group. The difference between these two propositions reached significance (χ2 = 3.96, df = 1, p = 0.047). As VRT is associated with the sustained-attention subdomain, our data suggest that this subdomain is disrupted in the CP group.

Cumulative life course adversity, mental health, and cognition in the UK biobank

The association between adversity and cognition varies according to the specific adversity, when the adversity was experienced, and the cognitive domains investigated. Disentangling the effect of adversity and the underlying mechanistic pathway is therefore difficult. The association between adversity (i.e., maltreatment) accumulated over the life course and cognitive flexibility, as well as two potential mediators (i.e., intra-individual variability in reaction time and depression) of this association, were investigated. Data stem from the baseline population of the UK Biobank study (N = 73,489, Mdnage = 56, SDage = 7.628, 55.740% of women). Cumulative life course adversity (specifically maltreatment) was measured with items based on the Childhood Trauma Questionnaire (CTS-5) and items adapted from the British Crime Survey. Depression was assessed with the Patient Health Questionnaire-9 (PHQ-9). Intra-individual variability in reaction time was measured with a reaction time test “snap game” and the Trail Making Test A and B were used as a measure of cognitive flexibility. A path analysis was performed on these data. Higher cumulative adverse experiences were associated with lower performance in cognitive flexibility (β = .016, p < .001, 95% CI [0.009, 0.024]), and this effect was partly mediated by the level of depression (22.727% of the total effect of cumulative life course adversity on cognitive flexibility was mediated by depression (β = .005, p < .001, 95% CI [0.004, 0.007])). No association between cumulative life course adverse experiences and intra-individual variability in reaction time was found, nor was any indirect association between cumulative life course adversity and performance in cognitive flexibility via intra-individual variability in reaction time. The association between cumulative life course adversity, depression, and performance in cognitive flexibility has been highlighted. In contrast, no indirect effect between cumulative life course adversity and performance in cognitive flexibility via intra-individual variability in reaction time was found, suggesting that it is not a potential mechanism underlying the association between cumulative life course adversity and executive function.

Intraindividual reaction time variability and academic achievement of primary school students: A longitudinal cross-lagged panel model

Attentional control indexed by intraindividual reaction time variability (IIRTV), which is found a crucial predictor of children's academic performance, may also be influenced by children's academic achievement. However, the bidirectional longitudinal relationships between children's IIRTV and academic achievement remain unclear. This study aimed to examine this issue in 211 Chinese primary school children (98 girls; Mage = 7.39 years, SDage = 0.49). Children's IIRTV was assessed using the flanker task - child version in three waves from the first to the third grade, and the children's final grades in Chinese and math for each year were collected from the school. The results showed that (1) IIRTV to the flanker task decreased with age; (2) IIRTV and Chinese achievement had a bidirectional longitudinal relationship, suggesting that IIRTV predicted prospective Chinese achievement; and Chinese achievement also predicted subsequent IIRTV in children. These findings have implications for promoting children's attentional control and academic performance.

Recreational Marijuana Use, Adolescent Cognitive Development, and Schizophrenia Susceptibility

BackgroundWe investigated how low marijuana (MJ) use levels, the typical use pattern in most adolescent users, affect cognitive maturation and schizophrenia risk. MethodsIn two complementary adolescent samples where the majority reported minimal MJ use, we compared cognitive performances before and after MJ use initiation. The Iowa sample (40 first-degree relatives and 54 second-degree relatives of patients with schizophrenia and 117 control subjects with no schizophrenia family history) underwent a battery of standardized neuropsychological tests at 0, 18, and 36 months. Based on self-administered Timeline Followback interviews, 26.5% of adolescents had emergent MJ use (eMJ) during follow-up. The second sample (n = 3463), derived from a birth cohort, received substance use and sustained attention assessments between ages 10 and 15 years. Mixed linear models and regression analyses tested the effects of eMJ on longitudinal changes in cognitive performance. ResultsIn the Iowa sample, longitudinal changes in 5 of 8 cognitive domains were significantly associated with eMJ. On sustained attention, visuospatial working memory, and executive sequencing, adolescents with eMJ showed less age-expected improved performance. In addition, first-degree relatives with eMJ were less improved on processing speed and executive reasoning than first-degree relatives without eMJ. In the birth cohort, greater intraindividual variability in reaction times (indicative of poorer sustained attention) was significantly associated with more frequent MJ use and with recreational use levels. ConclusionsNonheavy MJ use disrupts normal adolescent maturation and compounds aberrant adolescent maturation associated with familial schizophrenia risk. These findings underscore the importance of reducing adolescent MJ access in the context of increased availability to high-potency MJ.

A Comparison of the Effect of Physical Activity and Cognitive Training on Dual-Task Performance in Older Adults.

Studies suggest that cognitive training and physical activity can improve age-related deficits in dual-task performances. However, both of these interventions have never been compared in the same study. This article investigates the improvement in dual-task performance in 2 types of exercise training groups and a cognitive training group and explores if there are specific dual-task components that are more sensitive or more likely to improve following each type of training. Seventy-eight healthy inactive participants older than the age of 60 (M = 69.98, SD = 5.56) were randomized to one of three 12-week training programs: aerobic training (AET) = 26, gross motor abilities (GMA) = 27, and cognition (COG) = 25. Before and after the training program, the participants underwent physical fitness tests, and cognitive evaluations involving a computerized cognitive dual task. The AET consisted of high- and low-intensity aerobic training, the GMA of full-body exercises focusing on agility, balance, coordination, and stretching, and the COG of tablet-based exercises focusing on executive functions. Repeated-measures analysis of variance on reaction time data revealed a group × time interaction (F(2,75) = 11.91, p < .01) with COG having the greatest improvement, followed by a significant improvement in the GMA group. Secondary analysis revealed the COG to also improve the intraindividual variability in reaction time (F(1,24) = 8.62, p < .01), while the GMA improved the dual-task cost (F(1,26) = 12.74, p < .01). The results show that physical and cognitive training can help enhance dual-task performance by improving different aspects of the task, suggesting that different mechanisms are in play.

Neural substrates underpinning intra-individual variability in children with ADHD: A voxel-based morphometry study

Increased intra-individual variability (IIV) in reaction time (RT) is a key feature of attention-deficit/hyperactivity disorder (ADHD). However, little is known about neurobiology underpinnings of IIV in ADHD. We assessed 55 youths with ADHD, and 55 individually-matched typically developing control (TDC) with the MRI and Conners' Continuous Performance Test. The ex-Gaussian distribution of RT was estimated to capture IIV with the parameters σ (sigma) and τ (tau). The regional brain volumes, analyzed by voxel-based morphometry, were correlated with IIV parameters. We found both distinct and shared correlations among ADHD and TDC. For grey matter, there were significant σ-by-group interactions in the cingulate cortex and thalamus and also a τ-by-group interaction in the right inferior frontal gyrus. There was also shared negative associations between σ and regional volumes of the right posterior cerebellum and a positive association between τ and the right anterior insula. For white matter, there was a significant σ-by-group interaction in the genu of the corpus callosum and significant τ-by-group interactions in the right anterior corona radiata, the left splenium of the corpus callosum, and bilateral posterior cerebellum. There were also shared patterns that increased τ was associated with increased regional volumes of the right anterior corona radiata and decreased regional volumes of the right posterior limb of the internal capsule. This study highlights that brain regions responsible for the motor, salience processing and multimodal information integration are associated with increased IIV in youths with ADHD.

Assessment of Attentional Functioning in Health Professionals of a Brazilian Tertiary Referral Hospital for COVID-19.

This study is aimed at assessing differences in basic attentional functioning between substantial and minimal work-related exposure to COVID-19 patients in professionals working in a tertiary referral hospital in Rio de Janeiro, Brazil. Therefore, hospital employees performed a Continuous Visual Attention Test. This test consisted of a 90-second Go/No-Go task with 72 (80%) targets and 18 (20%) nontargets. For each participant, reaction time and intraindividual variability of reaction times of all correct target responses, as well as the number of omission and commission errors, were evaluated. Participants were divided into 2 groups based on their exposure to COVID-19 patients (substantial versus minimal exposure). The substantial exposure group consisted of participants with 24 hours/week or more direct contact with COVID-19 patients. This cut-off was based on the clear division between professionals working and not working with COVID-19 patients and considered that 12-hour and 24-hour daily shifts are common for hospital employees in Brazil. A MANCOVA was performed to examine between-group differences, using age, sleep quality, sex, education level, previous COVID-19 infection, and profession as covariates. Of 124 participants, 80 had substantial exposure and 44 had minimal exposure to COVID-19. The overall MANCOVA reached statistical significance (P = 0.048). Post hoc ANCOVA analysis showed that the substantial exposure group had a statistically significantly higher intraindividual variability of reaction time of all correct target responses (P = 0.017, Cohen′s δ = −0.55). This result remained after removing those with a previous COVID-19 infection (P = 0.010, Cohen′s δ = −0.64) and after matching groups for sample size (P = 0.004, Cohen′s δ = −0.81). No other variables reached statistical significance. Concluding, hospital professionals with a substantial level of exposure to patients with COVID-19 show a significant attention decrement and, thus, may be at a higher risk of accidental SARS-CoV-2 infection.

Manipulations of the Response-Stimulus Intervals as a Factor Inducing Controlled Amount of Reaction Time Intra-Individual Variability.

Aggrandized fluctuations in the series of reaction times (RTs) are a very sensitive marker of neurocognitive disorders present in neuropsychiatric populations, pathological ageing and in patients with acquired brain injury. Even though it was documented that processing inconsistency founds a background of higher-order cognitive functions disturbances, there is a vast heterogeneity regarding types of task used to compute RT-related variability, which impedes determining the relationship between elementary and more complex cognitive processes. Considering the above, our goal was to develop a relatively new assessment method based on a simple reaction time paradigm, conducive to eliciting a controlled range of intra-individual variability. It was hypothesized that performance variability might be induced by manipulation of response-stimulus interval’s length and regularity. In order to verify this hypothesis, a group of 107 healthy students was tested using a series of digitalized tasks and their results were analyzed using parametric and ex-Gaussian statistics of RTs distributional markers. In general, these analyses proved that intra-individual variability might be evoked by a given type of response-stimulus interval manipulation even when it is applied to the simple reaction time task. Collected outcomes were discussed with reference to neuroscientific concepts of attentional resources and functional neural networks.

The relation between falls risk and movement variability in Parkinson's disease.

Falls are a major health concern for older adults with Parkinson's disease (PD). This study was designed to examine differences in falls risk and its relation to changes in the average and variability (i.e. intra-individual variability) of reaction time (RT), finger tapping, standing balance and walking between healthy older adults and persons with PD. Thirty-nine adults with PD (70.0 ± 8.1years) and 29 healthy older adults (66.8 ± 10.4years) participated in this study. Falls risk (using the physiological profile assessment), gait, RT, balance and tapping responses were assessed for all persons. Results demonstrated that individuals with PD exhibited a greater risk of falling coupled with a general slowing of motor function covering declines in walking, RT and finger tapping. In addition, the movement responses of the PD group were more variable than the healthy older adults. Correlation results revealed group differences with regards to the neuromotor measures which were significantly correlated with falls risk. For the PD group, gait measures were highly correlated with their falls risk while, for the healthy older adults, falls risk was linked to balance measures even though PD persons had increased sway. Overall, persons with PD were at greater falls risk, moved slower and with increased variability compared to the healthy older adults. Further, while there are some similarities between the two groups in terms of those measures related to falls risk, there were also several differences which highlight that persons with PD can have different risk factors for falling compared to healthy adults of similar age.

Reaction Time Intraindividual Variability Reveals Inhibitory Deficits in Single- and Multiple-Domain Amnestic Mild Cognitive Impairment.

Amnestic mild cognitive impairment (aMCI), a prodromal stage of Alzheimer's disease and other dementias, is characterized by episodic memory impairment. Recent evidence has shown inhibitory control deficits in aMCI, but the extent of these deficits across inhibitory domains (i.e., response inhibition and interference control) and aMCI subtypes (i.e., single vs multiple domain) remains unclear. Few studies have included reaction time intraindividual variability (RT IIV) in these efforts. The aim of this study was to compare response inhibition and interference control between aMCI subtypes using measures of accuracy, mean RT, and RT IIV. We report data from 34 individuals with single-domain aMCI (sdaMCI, 66-86 years), 20 individuals with multiple-domain aMCI (mdaMCI, 68-88 years), and 52 healthy controls (HC, 64-88 years) who completed tasks of response inhibition (Go-NoGo) and interference control (Flanker). Group differences in accuracy, mean RT, and RT IIV were examined for both tasks. Individuals with mdaMCI had higher RT IIV than the other groups on both tasks. In RT IIV, we observed an interference control deficit in mdaMCI and sdaMCI relative to healthy controls, a finding not observed through accuracy or mean RT. RT IIV may detect subtle differences in inhibition deficits between aMCI subtypes that may not be evident with conventional behavioral measures. Findings support the supplementary use of RT IIV when assessing early executive function deficits.

Nucleus Accumbens Stimulation Modulates Inhibitory Control by Right Prefrontal Cortex Activation in Obsessive-Compulsive Disorder.

Inhibitory control is considered a compromised cognitive function in obsessive-compulsive (OCD) patients and likely linked to corticostriatal circuitry disturbances. Here, 9 refractory OCD patients treated with deep brain stimulation (DBS) were evaluated to address the dynamic modulations of large-scale cortical network activity involved in inhibitory control after nucleus accumbens (NAc) stimulation and their relationship with cortical thickness. A comparison of DBS "On/Off" states showed that patients committed fewer errors and exhibited increased intraindividual reaction time variability, resulting in improved goal maintenance abilities and proactive inhibitory control. Visual P3 event-related potentials showed increased amplitudes during Go/NoGo performance. Go and NoGo responses increased cortical activation mainly over the right inferior frontal gyrus and medial frontal gyrus, respectively. Moreover, increased cortical activation in these areas was equally associated with a higher cortical thickness within the prefrontal cortex. These results highlight the critical role of NAc DBS for preferentially modulating the neuronal activity underlying sustained speed responses and inhibitory control in OCD patients and show that it is triggered by reorganizing brain functions to the right prefrontal regions, which may depend on the underlying cortical thinning. Our findings provide updated structural and functional evidence that supports critical dopaminergic-mediated frontal-striatal network interactions in OCD.

Clinical Utility of a Reaction-Time Attention Task in the Evaluation of Cognitive Impairment in Elderly with High Educational Disparity.

The Clinical Dementia Rating (CDR) scale is commonly used to stage cognitive impairment, despite having educational limitations. In elderly with low education, a previous study has shown that intraindividual variability of reaction time (CV) and commission errors (CE), measured using a culture-free Go/No-Go task, can reliably distinguish early Alzheimer's disease (AD) from mild cognitive impairment (MCI) and healthy controls. We aimed to extend the clinical utility of this culture-free Go/No-Go task in a sample with high educational disparity. One hundred and ten participants with a wide range of years of formal education (0-14 years) were randomly selected from a geriatric unit and divided based on their CDR scores into cognitively unimpaired (CDR = 0), MCI (CDR = 0.5), and early AD (CDR = 1). All underwent a 90-s reaction-time test that measured the variables previously found to predict CDR in low educated elderly. Here we added years of formal education (educational level) to the model. Multivariate analyses compared differences in group means using educational level as confounding factor. A confirmatory discriminant analyses was performed, to assess if CDR scores could be predicted by the two Go/No-Go variables in a sample with high educational disparity. Over all three groups, differences in both CE and CV reached statistical significance (p < 0.05). The discriminant analysis demonstrated that CV and CE discriminated cognitively impaired from cognitively normal elderly. These results remained similar when discriminating MCI from cognitively unimpaired elderly. The Go/No-Go task reliably discriminates elderly with MCI from elderly without cognitive impairment independent of educational disparity.

Psychiatric comorbid disorders of cognition: a machine learning approach using 1175 UK Biobank participants

BackgroundConceptualising comorbidity is complex and the term is used variously. Here, it is the coexistence of two or more diagnoses which might be defined as ‘chronic’ and, although they may...

Detection of Cognitive Dysfunction in Elderly with a Low Educational Level Using a Reaction-Time Attention Task.

Scales for cognitive deterioration usually depend on education level. We aimed to study the clinical utility of a culture-free Go/No-Go task in a multi-ethnic cohort with low education level. Sixty-four participants with less than 4 years of formal education were included and divided on the basis of their Clinical-Dementia-Rate scores (CDR) into cognitively unimpaired (CDR = 0), mild cognitive impairment (MCI; CDR = 0.5), and early Alzheimer's disease (AD, CDR = 1). All underwent a 90-s Continuous Visual Attention Test. This test consisted of a 90-s Go/No-go task with 72 (80%) targets and 18 (20%) non-targets. For each participant, reaction times and intraindividual variability of reaction times of all correct target responses, as well as the number of omission and commission errors were evaluated. Coefficient of variability was calculated for each participant by dividing the standard deviation of the reaction times by the mean reaction time. A MANCOVA was performed to examine between-group differences using age and sex as covariates. Discriminate analysis was performed to find the most reliable test-variable to discriminate the three groups. Commission error, intraindividual variability of reaction time, and coefficient of variability progressively worsened with increasing CDR level. Discriminant analysis demonstrated that coefficient of variability was the best discriminant factor, followed by intraindividual variability of reaction time and commission error. The Go/No-Go task was able to discriminate people with MCI or early AD from controls in the setting of illiteracy.

Intraindividual reaction time variability as an index of attentional control acts as a moderator of the longitudinal relationships between marital quality and children’s externalizing problems

The current study investigated whether trial-to-trial intraindividual reaction time variability (IIRTV), which serves as an index of attentional control fluctuations, moderates the effect of marital quality at 7 years of age on the development of children’s externalizing problems from 7 to 9 years of age (N = 197). At the first assessment (T1), a flanker task was administered to children for assessing their IIRTV. The Chinese version of a marital quality questionnaire (Evaluating and Nurturing Relationship Issues, Communication, and Happiness [ENRICH]) and the Chinese version of the Child Behavior Checklist (CBCL) were completed by children’s mothers to assess marital quality and children’s externalizing problems. At the second and third assessments (T2 and T3), children’s externalizing problems were reassessed by their mothers. Growth curve analyses showed that boys’ externalizing problems were relatively high and significantly decreased over time, whereas girls’ externalizing problems were relatively low and stable. Importantly, the results indicated that boys’ IIRTV (but not girls’ IIRTV) and parental marital quality interactively predict the concurrent and developmental trajectories of externalizing problems. Specifically, boys with greater IIRTV were found to exhibit a relatively persistent high level of externalizing problems in the context of poor parental marital quality, whereas boys with lower IIRTV were found to exhibit a relatively low level of externalizing problems over time regardless of their parental marital quality. The findings suggest that poorer attentional control indexed by greater IIRTV is a robust predictor of boys’ externalizing problems and that better attentional control indexed by lower IIRTV may buffer the negative impact of adverse family environment on the development of boys’ externalizing problems.

The COMT rs4680 polymorphism, family functioning and preschoolers' attentional control indexed by intraindividual reaction time variability.

Trial-to-trial intraindividual reaction time variability (IIRTV) serves as an index of attentional control and related endogenous brain function. What determinants contribute to preschoolers' attentional control indexed by IIRTV remains unknown. The present study examined how catechol-o-methyltransferase (COMT) rs4680 polymorphism interacted with family functioning (cohesion and adaptability) to impact on preschoolers' attentional control indexed by IIRTV. One hundred forty-four preschool children (Mage =4.19, SD=0.63) completed the flanker task to assess their IIRTV. Their parents were asked to fill out the Family Adaptability and Cohesion Evaluation Scale II to assess family functioning. After controlling for age, socioeconomic status (SES) and mean reaction time, results showed that the COMT rs4680 polymorphism was positively associated with preschoolers' IIRTV at the 5% significance level (p=.02) but not after multiple testing adjustment (p=.08). Moreover the COMT rs4680 polymorphism significantly interacted with family functioning to impact on preschoolers' IIRTV and the interaction effects remained significant after correction for multiple testing (p=.01, ΔR2 =0.06 in congruent conditions; p=.04, ΔR2 =0.04 in combined conditions). In addition, the significant interaction between SES and COMT rs4680 polymorphism was also found in the present study (p=.01, ΔR2 =0.05 in congruent conditions; p=.05, ΔR2 =0.03 in combined conditions). No sex differences were found in the present sample. The findings of the present study expand our knowledge about the gene×environment underpinnings of children's attentional control and endogenous brain function, and provide evidence for the Vantage Sensitivity model on children's development.

Intraindividual reaction time variability, respiratory sinus arrhythmia, and children's externalizing problems

Intraindividual reaction time variability (IIRTV) is a unique cognitive function index that is independent of accuracy and has been found to be related to children's externalizing problems. Respiratory sinus arrhythmia (RSA) reactivity to challenge tasks was also found to be a potential influence factor of children's externalizing problems. The present study examined whether IIRTV interacts with RSA reactivity to relate to externalizing problems in children. The flanker task was administered to 168 early elementary school-age children to assess their IIRTV, and the Child Behavior Checklist-Chinese version (CBCL-CV) was completed by their parents to assess children's externalizing problems. Electrocardiogram data were collected during the resting and task period to calculate resting RSA and RSA reactivity. The results indicated that children's IIRTV was correlated with their externalizing problems. Importantly, IIRTV interacted with RSA reactivity to relate to externalizing problems. IIRTV was positively related to externalizing problems in children with RSA suppression but was not significantly related to externalizing problems in children with RSA augmentation during the task. These findings suggest that poor attentional or cognitive control, as indexed by greater IIRTV, is related to more externalizing problems. Moreover, during mild cognitive stress, greater RSA suppression might indicate poor physiological regulation, which is more likely to increase externalizing problems for children with poor attentional or cognitive control.