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Attention-deficit/hyperactivity disorder (ADHD) and autism spectrum disorder (ASD) are commonly comorbid, share genetic liability, and often exhibit overlapping cognitive impairments. Clarification of shared and distinct cognitive effects while considering comorbid symptoms across disorders has been lacking. In the current study, children ages 7-15 years assigned to three diagnostic groups:ADHD (n = 509), ASD (n = 97), and controls (n = 301) completed measures spanning the cognitive domains of attention/arousal, working memory, set-shifting, inhibition, and response variability. Specific processes contributing to response variability were examined using a drift diffusion model, which separately quantified drift rate (i.e., efficiency of information processing), boundary separation (i.e., speed-accuracy trade-offs), and non-decision time. Children with ADHD and ASD were impaired on attention/arousal, processing speed, working memory, and response inhibition, but did not differ from controls on measures of delayed reward discounting, set-shifting, or interference control. Overall, impairments in the ASD group were not attributable to ADHD symptoms using either continuous symptom measures or latent categorical grouping approaches. Similarly, impairments in the ADHD group were not attributable to ASD symptoms. When specific RT parameters were considered, children with ADHD and ASD shared impairments in drift rate. However, children with ASD were uniquely characterized by a wider boundary separation. Findings suggest a combination of overlapping and unique patterns of cognitive impairment for children with ASD as compared to those with ADHD, particularly when the processes underlying reaction time measures are considered separately.

Objective: Evidence suggests that caffeine use disproportionately impacts sleep functioning among youth with attention-deficit/hyperactivity disorder (ADHD). The present study aimed to examine the association of caffeine use with disrupted sleep, and to test moderating effects of ADHD, by leveraging differences within twin pairs to explore potential quasi-causal (i.e., within-pair) effects. Method: N = 765 complete same-sex twin pairs (mean age at baseline = 10.14 [SD = .5]; 49% girls; 73% white) from the ABCD study reported caffeine use and frequency of disrupted sleep; parents reported youth ADHD symptoms. Cotwin control analyses predicted disrupted sleep from caffeine use, ADHD, and their interaction at ages 10 and 12. Results: Neither quasi-causal within-pair effects of caffeine use on disrupted sleep, nor a moderating role of ADHD were identified. Posthoc biometric models indicated that genetic and environmental influences on these phenotypes may change over time, such that genetic influences on disrupted sleep began to emerge more robustly around early adolescence. Additionally, caffeine use and disrupted sleep, but not ADHD, displayed overlapping genetic influences (12-13% of total phenotypic variance) at age 10. Conclusions: In a sample of preadolescent twin pairs from the ABCD Study, we did not observe evidence that caffeine use was quasi-causally associated with disrupted sleep at this early developmental stage. However, caffeine use and disrupted sleep emerged with shared etiologic influences. In sum, this study sets the stage for examining these dynamic patterns in future examinations of this critical and timely ABCD study sample, as genetic and environmental influences on behavior are known to change throughout development. [ABSTRACT FROM AUTHOR]

Background: Intraindividual variability in reaction times (RT variability) has garnered increasing interest as an indicator of cognitive and neurobiological dysfunction in children with attention deficit hyperactivity disorder (ADHD). Recent theory and research has emphasized specific low-frequency patterns of RT variability. However, whether group differences are specific to low frequencies is not well examined. Method: Two studies are presented. The first is a quantitative review of seven previously published studies that have examined patterns of RT variability in ADHD. The second provides new data from a substantially larger sample of children than in prior studies ("N" [subscript Control] = 42; "N" [subscript ADHD] = 123). The children completed a choice RT task as part of a traditional go/stop task. Fast-Fourier transform analyses were applied to assess patterns of variability. Results: Quantitative review of previous studies indicated that children with ADHD demonstrate more low-frequency variability than non-ADHD controls (Hedge's "g" = 0.39; 95% CI: 0.16--0.62), but an equivalent excess variability in a faster frequency comparison band ("g" = 0.36; 95% CI: 0.03--0.69), with a trivial and nonsignificant difference between ESs in each band. New data replicated results of the quantitative review with nearly identical effects in the low-frequency ("g" = 0.39; 95% CI: 0.05--0.75) and faster frequency comparison bands ("g" = 0.40; 95% CI: 0.04--0.74) and no evidence of diagnosis (times) frequency interaction ("p" = 0.954). Conclusions: Results suggest that theories of RT variability in ADHD that focus on low-frequency variability will need to be modified to account for the presence of variability at a broader range of frequencies. (Contains 3 tables and 2 figures.)

We present two studies that examined developmental differences in the implicit and explicit acquisition of category knowledge. College-attending adults consistently outperformed school-age children on two separate information-integration paradigms due to children's more frequent use of an explicit rule-based strategy. Accuracy rates were also higher for adults on a unidimensional rule-based task due to children's more frequent use of the irrelevant dimension to guide their behavior. Results across these two studies suggest that the ability to learn categorization structures may be dependent on a child's ability to inhibit output from the explicit system.

Although motivation and cognition are often examined separately, recent theory suggests that a delay-averse motivational style may negatively impact development of executive functions (EFs), such as working memory (WM) and response inhibition (RI) for children with Attention Deficit Hyperactivity Disorder (ADHD; Sonuga-Barke, 2002). This model predicts that performance on delay aversion and EF tasks should be correlated for school-age children with ADHD. However, tests of these relationships remain sparse. Forty-five children ages 8 to 12 with ADHD and 46 non-ADHD controls completed tasks measuring EFs and delay aversion. Children with ADHD had poorer WM and RI than non-ADHD controls, as well as nonsignificantly worse delay aversion. Consistent with previous research, RI was not related to delay aversion. However, delay aversion did predict WM scores for children with and without ADHD. Implications for the dual-pathway hypothesis and future research on cognitive and motivational processing in ADHD are discussed. (Contains 3 tables.)

Objective: Reaction time variability (RTV) has been estimated using Gaussian, ex-Gaussian, and diffusion model (DM) indices. Rarely have studies examined interrelationships among these performance indices in childhood, and the use of reaction time (RT) computational models has been slow to take hold in the developmental psychopathology literature. Here, we extend prior work in adults by examining the interrelationships among different model parameters in the ABCD sample and demonstrate how computational models of RT can clarify mechanisms of time-on-task effects and sex differences in RTs. Method: This study utilized trial-level data from the stop signal task from 8916 children (9–10 years old) to examine Gaussian, ex-Gaussian, and DM indicators of RTV. In addition to describing RTV patterns, we examined interrelations among these indicators, temporal patterns, and sex differences. Results: There was no one-to-one correspondence between DM and ex-Gaussian parameters. Nonetheless, drift rate was most strongly associated with standard deviation of RT and tau, while nondecisional processes were most strongly associated with RT, mu, and sigma. Performance worsened across time with changes driven primarily by decreasing drift rate. Boys were faster and less variable than girls, likely attributable to girls' wide boundary separation. Conclusions: Intercorrelations among model parameters are similar in children as has been observed in adults. Computational approaches play a crucial role in understanding performance changes over time and can also clarify mechanisms of group differences. For example, standard RT models may incorrectly suggest slowed processing speed in girls that is actually attributable to other factors. [ABSTRACT FROM AUTHOR]

Background: Clinical course in attention‐deficit/hyperactivity disorder (ADHD) is highly heterogeneous with respect to both core symptoms and associated features and impairment. Onset of comorbid anxiety and mood disorders during later childhood and adolescence is one critical aspect of divergent outcomes in ADHD. Characterizing heterogeneity in onset of anxiety and depression and identifying prospective predictors of these divergent courses may facilitate early identification of the children most at risk. Methods: A total of 849 children recruited for a case–control study of ADHD development, aged 7–12 years at baseline, completed up to six annual waves of comprehensive clinical and cognitive assessment, including multi‐informant behavior ratings, parent semi‐structured clinical diagnostic interviews, and measures of executive function (EF). Latent class growth curve analyses (LCGAs) characterized patterns of anxiety and depression over time. Trajectories were predicted from baseline parent‐rated child temperament, lab‐measured child EF, coded parental criticism, and child‐reported self‐blame for inter‐parental conflict. Results: Latent class growth curve analyses separately identified three trajectories for anxiety and three for depression: persistently high, persistently low, and increasing. Temperamental fear/sadness and irritability were independent predictors that interacted with family characteristics. Baseline parental criticism and self‐blame for inter‐parental conflict exerted influence but only in the context of low temperamental risk. Better baseline child working memory was associated with delayed onset of depression. Conclusions: The interaction of baseline child emotional features with EF or family environment predicted divergent courses of both anxiety and depression from middle‐childhood to mid‐adolescence. Results suggest modifiable risk factors associated with prospective differences in long‐term outcomes. [ABSTRACT FROM AUTHOR]

This study examined the process of cognitive skill acquisition under differential working memory (WM) load conditions in children with the primarily inattentive (n = 21) and the combined (n = 32) subtypes of childhood attention-deficit/hyperactivity disorder (ADHD) and compared the results with those of non-ADHD controls (n = 48). Children completed 2 tasks of cognitive skill acquisition: alphabet arithmetic and finger math. The tasks differed in the amount of WM required for execution (alphabet arithmetic required more) but were otherwise matched with respect to logical structure, design, and discriminatory power. As would be predicted if the WM of the to-be-learned task affected the ability of children with ADHD to develop automaticity for a complex cognitive skill, ADHD-related impairments in the development of automaticity were seen for alphabet arithmetic but not for finger math. Results not only are relevant to ongoing debate regarding the presence of effortful versus automatic cognitive deficits in ADHD but also have implications for the development of new psychoeducational interventions for children with ADHD. Keywords: ADHD, subtypes, working memory, skill acquisition, automaticity DOI: 10.1037/a0017862