How 'core' are motor timing difficulties in ADHD? A latent class comparison of pure and comorbid ADHD classes

Disentangling the relationships between motor control and cognitive control in young children with symptoms of ADHD

Children with ADHD experience difficulties with motor and cognitive control. However, the relationships between these symptoms are poorly understood. As a step toward improving treatment, this study investigated associations between specific aspects of motor control and cognitive control in children with varying levels of hyperactive-impulsive symptoms. A heterogeneous sample of 255 children of 4 to 10 years of age (median = 6.50, MAD = 1.36) completed a battery of tests probing motor generation, visuomotor fluency, visuomotor flexibility, cognitive inhibition, verbal and visuospatial working memory, and cognitive flexibility. Their caregivers were interviewed regarding their hyperactive-impulsive symptoms. 25.9% of the main sample met diagnostic criteria for ADHD. Multiple linear regression analysis was used to determine whether specific aspects of motor control were associated with specific aspects of cognitive control, and whether any associations were moderated by hyperactive-impulsive symptoms. Additionally, cognitive modeling (the drift diffusion model approximated with EZ-DM) was used to understand performance on a cognitive inhibition task. Visuomotor fluency was significantly associated with cognitive inhibition. Visuomotor flexibility was significantly associated with cognitive flexibility. There were no significant moderation effects. Cognitive modeling was inconclusive. In conclusion, the ability to fluently perform visually guided continuous movement is linked with the ability to inhibit the effects of distracting information. The ability to spontaneously use visual information to flexibly alter motor responses is related to the ability to cognitively shift from one frame of mind to another. These relationships appear to be quantitatively and qualitatively similar across the childhood hyperactive-impulsive continuum as rated by parents.

Road-Crossing Behavior in Complex Traffic Situations: A Comparison of Children With and Without ADHD

All children are vulnerable to pedestrian injuries, but previous research suggests children diagnosed with ADHD may have elevated risk. Child pedestrian injury risk also increases with increasing traffic volume and speed. The current study examined three hypotheses: (a) Pedestrian behavior of children with ADHD is riskier than that of typically-developing children; (b) Children's pedestrian behavior is riskier with increased traffic complexity; and (c) Pedestrian behavior of children with ADHD is influenced more by complex traffic situations than behavior of typically-developing children. A sample of 38 children ages 8-12 years, 45% diagnosed with ADHD, completed 21 virtual street-crossings, 7 in each of three levels of traffic complexity. Outcome measures included unsafe crossings, ratio of looking at traffic by time, start-delay to enter the road, time to contact with oncoming vehicles, and time waiting to cross. A repeated measure MANOVA and follow-up tests showed that all children had more unsafe crossings, shorter start-delays and shorter TTCs when exposed to increased traffic complexity compared to lighter traffic. Children with ADHD had more unsafe crossings than typically-developing children. Further, compared to typically-developing children, ADHD children had comparatively more unsafe crossings, lower time to contact and longer wait-time in more complex traffic environments. Executive function deficits among children with ADHD likely influence their behavior in complex traffic environments. Implications of the results for policy-making and preventive strategies are discussed.

Cognitive, social, and behavioral manifestations of the co-occurrence of autism spectrum disorder and attention-deficit/hyperactivity disorder: A systematic review

LAY ABSTRACT

This work aimed to review recent research on the characteristics of individuals who have both autism spectrum disorder and attention-deficit/hyperactivity disorder due to their high co-occurrence. Thirty-four studies were analyzed and main findings summarized in two content domains focusing on areas that could enhance our understanding of the cognitive and behavioral characteristics of individuals with autism spectrum disorder + attention-deficit/hyperactivity disorder (ASD+). Most of the results suggested that ASD+ is a co-occurring condition associated with more severe impairments in cognitive functioning, adaptive behavior, and increased likelihood to present more emotional/behavioral problems. These results will be helpful to provide improved care plans for individuals with both attention-deficit/hyperactivity disorder and autism spectrum disorder.