Causal models of attention-deficit/hyperactivity disorder: From common simple deficits to multiple developmental pathways
ABSTRACT Until recently, causal models of attention-deficit/hyperactivity disorder (ADHD) have tended to focus on the role of common, simple, core deficits. One such model highlights the role of executive dysfunction due to deficient inhibitory control resulting from disturbances in the frontodorsal striatal circuit and associated mesocortical dopaminergic branches. An alternative model presents ADHD as resulting from impaired signaling of delayed rewards arising from disturbances in motivational processes, involving frontoventral striatal reward circuits and mesolimbic branches terminating in the ventral striatum, particularly the nucleus accumbens. In the present article, these models are elaborated in two ways. First, they are each placed within their developmental context by consideration of the role of person x environment correlation and interaction and individual adaptation to developmental constraint. Second, their relationship to one another is reviewed in the light of recent data suggesting that delay aversion and executive functions might each make distinctive contributions to the development of the disorder. This provides an impetus for theoretical models built around the idea of multiple neurodevelopmental pathways. The possibility of neuropathologic heterogeneity in ADHD is likely to have important implications for the clinical management of the condition, potentially impacting on both diagnostic strategies and treatment options.
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ABSTRACT: Attention-deficit/hyperactivity disorder (ADHD) can be identified in the preschool years, but little is known about the correlates of ADHD symptoms in preschool children. Research to date suggests that factors such as temperament, personality, and neuropsychological functioning may be important in understanding the development of early ADHD symptomatology. The current study sought to extend this research by examining how cognitive and reactive control processes predict ADHD symptoms. Data were drawn from a larger study that measured the cognitive, social, and emotional functioning of preschool children. Eighty-seven children (aged 4-6 years) were evaluated using teacher report and laboratory task measures relevant to cognitive control (i.e., conscientiousness, working memory) and reactive control (i.e., neuroticism, delay of gratification) processes. In multiple regression analyses, cognitive control variables added unique variance in the prediction of both inattention and hyperactivity, but only reactive control variables added unique variance in the prediction of hyperactivity. The current findings align with past research suggesting that cognitive control processes (e.g., conscientiousness) are related to both inattention and hyperactivity/impulsivity, while reactive control processes (e.g., neuroticism) are more strongly related to hyperactivity/impulsivity in preschool children. Future longitudinal research utilizing various methods and measures is needed to understand how cognitive and reactive control processes contribute to ADHD symptom development.International Journal of Behavioral Development 10/2015; DOI:10.1177/0165025415575625 · 1.58 Impact Factor
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ABSTRACT: Ineffective parenting practices may maintain or exacerbate attention deficit/hyperactivity disorder (ADHD) symptoms and shape subsequent development of disruptive behavior disorders (DBD's) in youth with ADHD. Recent theoretical models have suggested that parenting may exert effects on ADHD via its role in child temperament. The current study aimed to evaluate the indirect effects of parenting dimensions on child ADHD symptoms via child temperament. Youth ages 6-17 years (N = 498; 50.4 % ADHD, 55 % male) completed a multi-stage, multi-informant assessment that included parent, child, and teacher report measures of parenting practices, child temperament, and ADHD symptoms. Statistical models examined the direct and indirect effects of maternal and paternal involvement, poor supervision, and inconsistent discipline on inattention and hyperactivity-impulsivity via child temperament and personality traits. Results indicated differential patterns of effect for negative and positive parenting dimensions. First, inconsistent discipline exerted indirect effects on both ADHD symptom dimensions via child conscientiousness, such that higher levels of inconsistency predicted lower levels of conscientiousness, which in turn, predicted greater ADHD symptomatology. Similarly, poor supervision also exerted indirect effects on inattention via child conscientiousness as well as significant indirect effects on hyperactivity-impulsivity via its impact on both child reactive control and conscientiousness. In contrast, primarily direct effects of positive parenting (i.e., involvement) on ADHD emerged. Secondary checks revealed that similar pathways may also emerge for comorbid disruptive behavior disorders. Current findings extend upon past work by examining how parenting practices influence child ADHD via with-in child mechanisms and provide support for multi-pathway models accounting for heterogeneity in the disorder.Journal of Abnormal Child Psychology 02/2015; DOI:10.1007/s10802-015-9982-1 · 3.09 Impact Factor
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ABSTRACT: Attention-deficit hyperactivity disorder (ADHD) does not exist. This explicit statement needs elucidation of course given ADHD is a common neurodevelopmental disorder, but it provides the reader with the impetus to reconsider long-held beliefs about this condition and its treatment. Surely, there is a disorder called ADHD from which this thesis is framed, but primary attention and hyperactivity-impulsivity problems are mediated by different albeit interrelated brain systems. Like many neurodevelopmental disorders (e.g., learning disabilities, autism spectrum disorder), the medical and psycho- logical professions have used a single, large inclusive ADHD diagnostic category to rep- resent children with different etiologies for their overt symptoms. Despite neurobiological differences among children diagnosed with ADHD, the clinical position that attention-deficit or primary attention problems are sufficient for ADHD identifi- cation undermines clinical practice. This commonly accepted dubious position not only undermines the diagnostic utility of our neuropsychological measures, but it attenuates treatment effects as well. Supported with evidence from our ongoing ADHD research program, this data-based review will support these contentions and provide implications for diagnosis and treatment of children with attention problems.Applied Neuropsychology 02/2015; 4(2). DOI:10.1080/21622965.2015.1005481 · 1.97 Impact Factor