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BackgroundAttention deficit hyperactivity disorder (ADHD) is frequently associated with poorer reading ability; however, the specific neuropsychological domains linking this co-occurrence remain unclear. This study evaluates information-processing characteristics as possible neuropsychological links between ADHD symptoms and RA in a community-based sample of children and early adolescents with normal IQ (⩾70).MethodThe participants (n = 1857, aged 6–15 years, 47% female) were evaluated for reading ability (reading single words aloud) and information processing [stimulus discriminability in the two-choice reaction-time task estimated using diffusion models]. ADHD symptoms were ascertained through informant (parent) report using the Development and Well-Being Assessment (DAWBA). Verbal working memory (VWM; digit span backwards), visuospatial working memory (VSWM, Corsi Blocks backwards), sex, socioeconomic status, and IQ were included as covariates.ResultsIn a moderated mediation model, stimulus discriminability mediated the effect of ADHD on reading ability. This indirect effect was moderated by age such that a larger effect was seen among younger children.ConclusionThe findings support the hypothesis that ADHD and reading ability are linked among young children via a neuropsychological deficit related to stimulus discriminability. Early interventions targeting stimulus discriminability might improve symptoms of inattention/hyperactivity and reading ability. [ABSTRACT FROM AUTHOR]

Background.Taxometric and behavioral genetic studies suggest that attention deficit hyperactivity disorder (ADHD) is best modeled as a dimension rather than a category. We extended these analyses by testing for the existence of putative ADHD-related deficits in basic information processing (BIP) and inhibitory-based executive function (IB-EF) in individuals in the subclinical and full clinical ranges. Consistent with the dimensional model, we predicted that ADHD-related deficits would be expressed across the full spectrum, with the degree of deficit linearly related to the severity of the clinical presentation.Method.A total of 1547 children (aged 6–12 years) participated in the study. The Development and Well-Being Assessment (DAWBA) was used to classify children into groups according to levels of inattention and hyperactivity independently: (1) asymptomatic, (2) subthreshold minimal, (3) subthreshold moderate and (4) clinical ADHD. Neurocognitive performance was evaluated using a two-choice reaction time task (2C-RT) and a conflict control task (CCT). BIP and IB-EF measures were derived using a diffusion model (DM) for decomposition of reaction time (RT) and error data.Results.Deficient BIP was found in subjects with minimal, moderate and full ADHD defined in terms of inattention (in both tasks) and hyperactivity/impulsivity dimensions (in the 2C-RT). The size of the deficit increased in a linear manner across increasingly severe presentations of ADHD. IB-EF was unrelated to ADHD.Conclusions.Deficits in BIP operate at subclinical and clinical levels of ADHD. The linear nature of this relationship provides support for a dimensional model of ADHD in which diagnostic thresholds are defined in terms of clinical and societal burden rather than representing discrete pathophysiological states. [ABSTRACT FROM AUTHOR]

BackgroundBoth inhibitory-based executive functioning (IB-EF) and basic information processing (BIP) deficits are found in clinic-referred attention deficit hyperactivity disorder (ADHD) samples. However, it remains to be determined whether: (1) such deficits occur in non-referred samples of ADHD; (2) they are specific to ADHD; (3) the co-morbidity between ADHD and oppositional defiant disorder/conduct disorder (ODD/CD) has additive or interactive effects; and (4) IB-EF deficits are primary in ADHD or are due to BIP deficits.MethodWe assessed 704 subjects (age 6–12 years) from a non-referred sample using the Development and Well-Being Assessment (DAWBA) and classified them into five groups: typical developing controls (TDC; n = 378), Fear disorders (n = 90), Distress disorders (n = 57), ADHD (n = 100), ODD/CD (n = 40) and ADHD+ODD/CD (n = 39). We evaluated neurocognitive performance with a Two-Choice Reaction Time Task (2C-RT), a Conflict Control Task (CCT) and a Go/No-Go (GNG) task. We used a diffusion model (DM) to decompose BIP into processing efficiency, speed–accuracy trade-off and encoding/motor function along with variability parameters.ResultsPoorer processing efficiency was found to be specific to ADHD. Faster encoding/motor function differentiated ADHD from TDC and from fear/distress whereas a more cautious (not impulsive) response style differentiated ADHD from both TDC and ODD/CD. The co-morbidity between ADHD and ODD/CD reflected only additive effects. All ADHD-related IB-EF classical effects were fully moderated by deficits in BIP.ConclusionsOur findings challenge the IB-EF hypothesis for ADHD and underscore the importance of processing efficiency as the key specific mechanism for ADHD pathophysiology. [ABSTRACT FROM AUTHOR]

Background. Preliminary research implicates threat-related attention biases in paediatric anxiety disorders. However, major questions exist concerning diagnostic specificity, effects of symptom-severity levels, and threatstimulus exposure durations in attention paradigms. This study examines these issues in a large, community schoolbased sample. Method. A total of 2046 children (ages 6-12 years) were assessed using the Development and Well Being Assessment (DAWBA), Childhood Behavior Checklist (CBCL) and dot-probe tasks. Children were classified based on presence or absence of 'fear-related' disorders, 'distress-related' disorders, and behavioural disorders. Two dot-probe tasks, which differed in stimulus exposure, assessed attention biases for happy-face and threat-face cues. The main analysis included 1774 children. Results. For attention bias scores, a three-way interaction emerged among face-cue emotional valence, diagnostic group, and internalizing symptom severity (F = 2.87, p < 0.05). This interaction reflected different associations between internalizing symptom severity and threat-related attention bias across diagnostic groups. In children with no diagnosis (n=1411, mean difference=11.03, S.E.=3.47, df=1, p<0.001) and those with distress-related disorders (n = 66, mean difference = 10.63, S.E. = 5.24, df=1, p < 0.05), high internalizing symptoms predicted vigilance towards threat. However, in children with fear-related disorders (n = 86, mean difference = -11.90, S.E. = 5.94, df=1, p < 0.05), high internalizing symptoms predicted an opposite tendency, manifesting as greater bias away from threat. These associations did not emerge in the behaviour-disorder group (n = 211). Conclusions. The association between internalizing symptoms and biased orienting varies with the nature of developmental psychopathology. Both the form and severity of psychopathology moderates threat-related attention biases in children. [ABSTRACT FROM AUTHOR]

Background. Most information about the lifetime prevalence of mental disorders comes from retrospective surveys, but how much these surveys have undercounted due to recall failure is unknown. We compared results from a prospective study with those from retrospective studies. Method. The representative 1972-1973 Dunedin New Zealand birth cohort (n=1037) was followed to age 32 years with 96% retention, and compared to the national New Zealand Mental Health Survey (NZMHS) and two US National Comorbidity Surveys (NCS and NCS-R). Measures were research diagnoses of anxiety, depression, alcohol dependence and cannabis dependence from ages 18 to 32 years. Results. The prevalence of lifetime disorder to age 32 was approximately doubled in prospective as compared to retrospective data for all four disorder types. Moreover, across disorders, prospective measurement yielded a mean past-year-to-lifetime ratio of 38% whereas retrospective measurement yielded higher mean past-year-to-lifetime ratios of 57% (NZMHS, NCS-R) and 65% (NCS). Conclusions. Prospective longitudinal studies complement retrospective surveys by providing unique information about lifetime prevalence. The experience of at least one episode of DSM-defined disorder during a lifetime may be far more common in the population than previously thought. Research should ask what this means for etiological theory, construct validity of the DSM approach, public perception of stigma, estimates of the burden of disease and public health policy. [ABSTRACT FROM AUTHOR]