In the 1950's, many experts believed hyperkinesis was a neurotic reaction to inner conflicts arising from early family experiences. In the 1990's, many experts believed ADHD to be "genetic" (without a mechanistic explanation of what that meant). Both views appear naïve today in a scientific world grappling with the complexity…

Objective: Identification of biomarkers is a priority for attention-deficit/hyperactivity disorder (ADHD). Studies have documented macrostructural brain alterations in ADHD, but few have examined white matter microstructure, particularly in preadolescent children. Given dramatic white matter maturation across childhood, microstructural differences…

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…

Objective: How best to capture heterogeneity in attention-deficit/hyperactivity disorder (ADHD) using biomarkers has been elusive. This study evaluated whether emotion reactivity and regulation provide a means to achieve this. Method: Participants were classified into three groups: children with ADHD plus low prosocial behavior (hypothesized to be…

Oppositional-Defiant Disorder (ODD) and Attention-Deficit/Hyperactivity Disorder (ADHD) are highly comorbid, a phenomenon thought to be due to shared etiological factors and mechanisms. Little work has attempted to chart multiple-level-of-analysis pathways (i.e., simultaneously including biological, environmental, and trait influences) to ODD and…

Objective: The role of diet and of food colors in attention-deficit/hyperactivity disorder (ADHD) or its symptoms warrants updated quantitative meta-analysis, in light of recent divergent policy in Europe and the United States. Method: Studies were identified through a literature search using the PubMed, Cochrane Library, and PsycNET databases…

Background: A key underlying process that may contribute to attention-deficit/hyperactivity disorder (ADHD) involves alterations in reward evaluation, including assessing the relative value of immediate over delayed rewards. This study examines whether children with ADHD discount the value of delayed rewards to a greater degree than typically…

Reviews salient emerging themes in the scientific literature related to identifying etiology and pathophysiology of ADHD. While bypassing the need for new treatment research, the review highlights three themes. First, recognition of the epigenetic effects is expected to revitalize the search for and mapping of early environmental influences on the…

Attention-Deficit/Hyperactivity Disorder (ADHD) is a prime candidate for exploration of gene-by-environment interaction (i.e., G x E), particularly in relation to dopamine system genes, due to strong evidence that dopamine systems are dysregulated in the disorder. Using a G x E design, we examined whether the "DRD4" promoter 120-bp tandem repeat…

Despite growing interest in conceptualizing ADHD as involving disrupted emotion regulation, few studies have examined the physiological mechanisms related to emotion regulation in children with this disorder. This study examined parasympathetic and sympathetic nervous system reactivity via measures of respiratory sinus arrhythmia (RSA) and cardiac…

An important research question is whether Attention Deficit Hyperactivity Disorder (ADHD) is related to early- or late-stage attentional control mechanisms and whether this differentiates a nonhyperactive subtype (ADD). This question was addressed in a sample of 145 ADD/ADHD and typically developing comparison adolescents (aged 13-17). Attentional…

Objective: The present study examined the role of negative emotions on driving performance in relation to ADHD, by comparing young adults scoring high on measures of ADHD (n = 20) with a control group (n = 22). Method: The authors used cardiorespiratory physiological measures, simulated driving behavior, and self-report to examine how participants…

Personality traits may be viable candidates for mediators of the relationship between genetic risk and ADHD. Participants were 578 children (331 boys; 320 children with ADHD) between the ages of six and 18. Parents and teachers completed a comprehensive, multi-stage diagnostic procedure to assess ADHD and comorbid disorders. Mother completed the…

Background: Attention-deficit/hyperactivity disorder (ADHD) is presumed to be heterogeneous, but the best way to describe this heterogeneity remains unclear. Considerable evidence has accrued suggesting that inattention versus hyperactivity-impulsivity symptom domains predict distinct clinical outcomes and may have partially distinct etiological…

Background: Recent studies have suggested that child attention-deficit/hyperactivity disorder (ADHD) and its symptom domains are related to blood lead level, even at background exposure levels typical in western countries. However, recent studies disagreed as to whether lead was related to inattention or hyperactivity-impulsivity within the ADHD…