Differential effects of atomoxetine on executive functioning and lexical decision in attention-deficit/hyperactivity disorder and reading disorder.

OBJECTIVE: The effects of a promising pharmacological treatment for attention-deficit/hyperactivity disorder (ADHD), atomoxetine, were studied on executive functions in both ADHD and reading disorder (RD) because earlier research demonstrated an overlap in executive functioning deficits in both disorders. In addition, the effects of atomoxetine were explored on lexical decision. METHODS: Sixteen children with ADHD, 20 children with ADHD + RD, 21 children with RD, and 26 normal controls were enrolled in a randomized placebo-controlled crossover study. Children were measured on visuospatial working memory, inhibition, and lexical decision on the day of randomization and following two 28-day medication periods. RESULTS: Children with ADHD + RD showed improved visuospatial working memory performance and, to a lesser extent, improved inhibition following atomoxetine treatment compared to placebo. No differential effects of atomoxetine were found for lexical decision in comparison to placebo. In addition, no effects of atomoxetine were demonstrated in the ADHD and RD groups. CONCLUSION: Atomoxetine improved visuospatial working memory and to a lesser degree inhibition in children with ADHD + RD, which suggests differential developmental pathways for co-morbid ADHD + RD as compared to ADHD and RD alone. CLINICAL TRIAL REGISTRY: B4Z-MC-LYCK, NCT00191906; http://clinicaltrials.gov/ct2/show/NCT00191906.

Study design, baseline patient characteristics and intervention in a cross-cultural framework: results from the ADORE study.

OBJECTIVE: To describe the methodology and to present the baseline findings of the Attention-deficit/hyperactivity Disorder Observational Research in Europe (ADORE) study, the primary objective of which is to describe the relationship between treatment regimen prescribed and quality of life of children with ADHD in actual practice. METHODS: In this 2-year prospective observational study, data on diagnosis, prescribed treatment and outcomes of ADHD were collected at seven time points by paediatricians and child psychiatrists on 1,573 children recruited in 10 European countries. The data presented here from the 1,478 patients included in the analyses describe the baseline condition, initial treatment regimen prescribed and quality of life of families with children with ADHD. RESULTS: Patients had a mean age of 9.0 years (SD 2.5) and 84% were male. Physicians diagnoses were made using DSM-IV (43%), ICD-10 (32%) and both DSM-IV and ICD-10 (12%). Mean age of awareness of a problem was 5.1 years, suggesting an average delay of approximately 4 years between awareness and diagnosis of ADHD. Baseline ADHD rating scale scores (physician-rated) indicated moderate to severe ADHD. Parent-rated SDQ scores were in agreement and suggested significant levels of co-existing problems. CGI-S, CGAS and CHIP-CE scores also indicated significant impairment. Patients were offered the following treatments after the initial assessment: pharmacotherapy (25%), psychotherapy (19%), combination of pharmacotherapy and psychotherapy (25%), other therapy (10%) and no treatment (21%). CONCLUSION: The ADORE study shows that ADHD is similarly recognised across 10 European countries and that the children are significantly impaired across a wide range of domains. In this respect, they resemble children described in previous ADHD samples.

Executive functioning in boys with ADHD: primarily an inhibition deficit?

This study was aimed at: (1) testing whether boys with Attention Deficit/Hyperactivity Disorder (ADHD) demonstrate a deficit in response inhibition and deficits in other executive functions (EF), or alternatively, demonstrate a deficit in only response inhibition; (2) investigating which role associated factors, such as IQ, age, and performance on non-EF tasks play in EF in ADHD; (3) studying the association between the three different forms of inhibition studied here. Boys with ADHD were compared with normal control (NC) boys on five domains of executive functioning: inhibition (inhibition of a prepotent response, inhibition of an ongoing response, and interference control), planning, set-shifting, working memory, and verbal fluency. Boys with ADHD demonstrated deficits in interference control, inhibition of an ongoing response, planning, and letter fluency. After controlling for age, IQ, and non-EF measures, none of the EF deficits in ADHD remained. Finally, correlations between different inhibition measures were generally low, and correlations within domains of inhibition were not higher than correlations between domains of inhibition. This calls into question the distinctiveness of the different forms of response inhibition.

The effect of methylphenidate on three forms of response inhibition in boys with AD/HD.

The current study was aimed at (a) investigating the effect of three doses methylphenidate (MPH) and placebo on inhibition of a prepotent response, inhibition of an ongoing response, and interference control in Attention Deficit/Hyperactivity Disorder (AD/HD), and (b) studying dose-response relations for the three forms of response inhibition. To meet these aims, the following tasks were selected: two versions of the Stop Paradigm for inhibition of a prepotent response, a Circle Tracing Task and a recently developed Follow Task for inhibition of an ongoing response, and the Stroop Color-Word Test and an Eriksen Flanker Task for interference control. These tasks were administered to 23 boys with AD/HD during four treatment conditions: 5 mg MPH, 10 mg MPH, 20 mg MPH, and placebo. A pseudorandomized, multiple-blind, placebo-controlled, within-subject design was used. As hypothesized, inhibitory control in children with AD/HD improved under MPH compared to placebo. However, this effect was only significant for inhibition of a prepotent response and inhibition of an ongoing response (as measured by the Follow Task), but not for interference control. The relation between treatment condition and response was linear. However, this linear relation was due to improved inhibitory control under MPH compared to placebo, because no effects of MPH dose were observed for any of the response inhibition measures.