Inhibitory function and working memory in attention deficit/hyperactivity disorder and pervasive developmental disorders: does a continuous cognitive gradient explain ADHD and PDD traits?

Infant Attentional behaviors Are Associated With ADHD Symptomatology and Executive Function in Early Childhood

Objective: We explored associations between infant attentional behaviors as measured by the First Year Inventory (FYIv2.0) and dimensional ratings of ADHD symptomatology and executive function (EF) in early childhood. Methods: This study included parents (N = 229) who filled out the FYIv2.0 when their children were 12 months of age. When children were approximately 54 months (4.5 years) of age, parents completed reports of children's ADHD symptomatology and EF abilities. Correlation and regression analyses were conducted among measures. Results: We found significant associations among the variables of interest, both cross-sectionally and longitudinally, as well as gender differences. Notably, non-social sensory attention (NSA) was significantly related to 54-month ADHD symptom severity. All three 12-month attention variables were significantly related to 54-month EF. Conclusion: Results suggest that infant attentional behaviors predict later ADHD-related behaviors in early childhood. Future research should explore associations using laboratory-based measures and could inform early intervention efforts.

Inhibition in developmental disorders: A comparison of inhibition profiles between children with autism spectrum disorder, attention-deficit/hyperactivity disorder, and comorbid symptom presentation

LAY ABSTRACT

Many children with autism spectrum disorder (ASD) also have symptoms of attention-deficit hyperactivity disorder (ADHD). Children with ASD and ADHD often experience difficulties with inhibition. This study had the goal of understanding inhibition in children with ASD, ADHD, ASD + ADHD, and children who are typically developing (TD) using tasks that measured several aspects of inhibition. Results indicate that children with ASD + ADHD had greater difficulty inhibiting behavioral responses than TD children. Children with ASD + ADHD also differed from children with ASD and with ADHD in their inhibition of distracting information and strategic slowing of response speed. The four groups did not differ in their avoidance of potential losses. Children with ASD + ADHD exhibit a unique profile of inhibition challenges suggesting they may benefit from targeted intervention matched to their abilities.

Associations Between Limbic System White Matter Structure and Socio-Emotional Functioning in Children with ADHD + ASD

Children with attention deficit/hyperactivity disorder (ADHD) combined with autism spectrum disorder (ASD) symptoms (ADHD + ASD) have poorer social and emotional functioning than those with ADHD alone. However, no studies have specifically examined the associations between ASD symptoms, measures of social and emotional functioning and limbic system white matter microstructure. Tractography on the cingulum, uncinate fasciculus and fornix were performed for 151 children with (N = 78) and without (N = 73) ADHD. Participants in the ADHD group who scored 11 or above on the Social Communication Questionnaire were classified as the ADHD + ASD group (N = 16). Significant differences in mean cingulum FA were present between the control group and the ADHD (all) group, however, no significant differences were seen between the ADHD and ADHD + ASD groups. Despite this, significant associations were seen between mean FA of the left cingulum and emotional problems for the ADHD + ASD group. Results give greater insights into the specific biological basis of emotional problems in the ADHD + ASD group, indicating that the cingulum may play a role.

ADHD symptoms and learning behaviors in children with ASD without intellectual disability. A mediation analysis of executive functions

In spite of its importance for education, the relationship between learning behaviors (LB), attention deficit hyperactivity disorder symptoms (ADHD) and executive functioning (EF) in children with autism spectrum disorder (ASD) has hardly been explored. The first objective of the present study was to compare children with ASD without intellectual disability and children with typical development (TD) on ADHD symptoms and learning behaviors: Motivation/competence, attitude toward learning, persistence on the task, and strategy/flexibility. The second objective was to analyze the mediator role of behavioral regulation and metacognition components of EF between ADHD symptoms and learning behaviors in children with ASD. Participants were 89 children between 7 and 11 years old, 52 with ASD and 37 with TD, matched on age and intelligence. Their teachers filled out questionnaires assessing executive functioning as well as learning behaviors. Parents and teachers reported on inattention and hyperactivity/impulsivity behaviors. Compared to children with TD, children with ASD presented significantly more ADHD symptoms and poorer learning behaviors. In addition, there were significant mediation effects of the behavioral regulation index (BRI) and metacognition index (MI) of EF, indicating that both are part of the route through which ADHD symptoms impact to learning behaviors of children with ASD.

Relationship Between Executive Functioning and Symptoms of Attention-Deficit/Hyperactivity Disorder and Autism Spectrum Disorder in 6-8 Year Old Children

This study examined relationships between executive functioning (EF) and ADHD/ASD symptoms in 339 6-8 year-old children to characterise EF profiles associated with ADHD and ADHD + ASD. ADHD status was assessed using screening surveys and diagnostic interviews. ASD symptoms were measured using the Social Communication Questionnaire, and children completed assessments of EF. We found the EF profile of children with ADHD + ASD did not differ from ADHD-alone and that lower-order cognitive skills contributed significantly to EF. Dimensionally, ASD and inattention symptoms were differentially associated with EF, whereas hyperactivity symptoms were unrelated to EF. Differences between categorical and dimensional findings suggest it is important to use both diagnostic and symptom based approaches in clinical settings when assessing these children's functional abilities.

A review of executive function deficits in autism spectrum disorder and attention-deficit/hyperactivity disorder

Executive dysfunction has been shown to be a promising endophenotype in neurodevelopmental disorders such as autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD). This article reviewed 26 studies that examined executive function comparing ASD and/or ADHD children. In light of findings from this review, the ASD + ADHD group appears to share impairment in both flexibility and planning with the ASD group, while it shares the response inhibition deficit with the ADHD group. Conversely, deficit in attention, working memory, preparatory processes, fluency, and concept formation does not appear to be distinctive in discriminating from ASD, ADHD, or ASD + ADHD group. On the basis of neurocognitive endophenotype, the common co-occurrence of executive function deficits seems to reflect an additive comorbidity, rather than a separate condition with distinct impairments.

Acute oral administration of low doses of methylphenidate targets calretinin neurons in the rat septal area

Methylphenidate (MPD) is a commonly administered drug to treat children suffering from attention deficit hyperactivity disorder (ADHD). Alterations in septal driven hippocampal theta rhythm may underlie attention deficits observed in these patients. Amongst others, the septo-hippocampal connections have long been acknowledged to be important in preserving hippocampal function. Thus, we wanted to ascertain if MPD administration, which improves attention in patients, could affect septal areas connecting with hippocampus. We used low and orally administered MPD doses (1.3, 2.7 and 5 mg/Kg) to rats what mimics the dosage range in humans. In our model, we observed no effect when using 1.3 mg/Kg MPD; whereas 2.7 and 5 mg/Kg induced a significant increase in c-fos expression specifically in the medial septum (MS), an area intimately connected to the hippocampus. We analyzed dopaminergic areas such as nucleus accumbens and striatum, and found that only 5 mg/Kg induced c-fos levels increase. In these areas tyrosine hydroxylase correlated well with c-fos staining, whereas in the MS the sparse tyrosine hydroxylase fibers did not overlap with c-fos positive neurons. Double immunofluorescence of c-fos with neuronal markers in the septal area revealed that co-localization with choline acethyl transferase, parvalbumin, and calbindin with c-fos did not change with MPD treatment; whereas, calretinin and c-fos double labeled neurons increased after MPD administration. Altogether, these results suggest that low and acute doses of methylphenidate primary target specific populations of caltretinin medial septal neurons.