Impulsiveness as a timing disturbance: neurocognitive abnormalities in attention-deficit hyperactivity disorder during temporal processes and normalization with methylphenidate Effects of Methylphenidate on Impulsive Responding in Children With Attention-Deficit Hyperactivity Disorder The effect of polyphenolic extract from pine bark, Pycnogenol® on the level of glutathione in children suffering from attention deficit hyperactivity disorder (ADHD) Efficacy of methylphenidate in children with attention-deficit hyperactivity disorder and learning disabilities: a randomized crossover trial.
We argue that impulsiveness is characterized by compromised timing functions such as premature motor timing , decreased tolerance to delays , poor temporal foresight and steeper temporal discounting . A model illustration for the association between impulsiveness and timing deficits is the impulsiveness disorder of attention-deficit hyperactivity disorder ( ADHD ) . Children with ADHD have deficits in timing processes of several temporal domains and the neural substrates of these compromised timing functions are strikingly similar to the neuropathology of ADHD . We review our published and present novel functional magnetic resonance imaging data to demonstrate that ADHD children show dysfunctions in key timing regions of prefrontal , cingulate , striatal and cerebellar location during temporal processes of several time domains including time discrimination of milliseconds , motor timing to seconds and temporal discounting of longer time intervals . Given that impulsiveness , timing abnormalities and more specifically ADHD have been related to dopamine dysregulation , we tested for and demonstrated a normalization effect of all brain dysfunctions in ADHD children during time discrimination with the dopamine agonist and treatment of choice , methylpheni date . This review together with the new empirical findings demonstrates that neurocognitive dysfunctions in temporal processes are crucial to the impulsiveness disorder of ADHD and provides first evidence for normalization with a dopamine reuptake inhibitor The present investigation examined the effects of methylpheni date on impulsivity in children with attention-deficit hyperactivity disorder ( ADHD ) . A task was design ed to measure empirically the ADHD child 's proclivity to blurt out incorrect answers before giving a final and /or correct response . Twenty-six ADHD children referred for double-blind placebo-controlled assessment of medication responsiveness and 14 non-ADHD controls were given a visual search word-matching task to assess impulsive responding . An analysis of covariance showed that ADHD children on methylpheni date made fewer impulsive errors than ADHD children on placebo . The control group made fewer impulsive errors than the ADHD children in the placebo condition , but the performance of the ADHD children on medication approximated the performance of the children without ADHD . These preliminary findings suggest that the word-matching task may be a useful tool for assessing impulsive responding and determining the benefits of stimulant medication on impulsivity . ( J Child Neurol 1993;8:157 - 163 ) Abstract Attention deficit hyperactivity disorder ( ADHD ) belongs to the neurodevelopmental disorders characterized by impulsivity , distractibility and hyperactivity . In the pathogenesis of ADHD genetic and non-genetic factors play an important role . It is assumed that one of non-genetic factors should be oxidative stress . Pycnogenol ® , an extract from the pine bark , consists of bioflavonoids , catechins , procyanidins and phenolic acids . Pycnogenol ® acts as powerful antioxidant , chelating agent ; it stimulates the activities of some enzymes , like SOD , eNOS , and exhibits other biological activities . Aim : The aim of this r and omized , double-blind , placebo-controlled trial was to investigate the influence of administered Pycnogenol ® or placebo on the level of reduced ( GSH ) and oxidized ( GSSG ) glutathione in children suffering from ADHD and on total antioxidant status ( TAS ) . This is the first investigation of the redox glutathione state in relation to ADHD . Results : One month of Pycnogenol ® administration ( 1 mg/kg body weight/day ) caused a significant decrease in GSSG and a highly significant increase in GSH levels as well as improvement of GSH/GSSG ratio in comparison to a group of patients taking a  placebo . TAS in children with ADHD was decreased in comparison with reference values . Pycnogenol ® administration normalizes TAS of ADHD children OBJECTIVE To determine whether children with attention-deficit hyperactivity disorder ( ADHD ) and learning disabilities respond differently to methylpheni date ( MPH ) compared with children with ADHD only . METHODS We conducted a prospect i ve , double-blind , placebo-controlled , r and omized , 2-week crossover trial of MPH , during which response to MPH was assessed . Learning ability was appraised using the Wide Range Achievement Test , Revised ( WRAT-R ) , for English-speaking students and the Test de rendement pour francophones for French-speaking students . The study was conducted at the Douglas Hospital , a McGill University-affiliated teaching hospital in Montréal . Ninety-five children , aged 6 - 12 years , who met the Diagnostic and Statistical Manual of Mental Disorders , fourth edition ( DSM-IV ) , criteria for ADHD participated in the study , which ran from 2001 to 2004 . The outcome measure used was the Consensus Clinical Response , an indicator of the degree of clinical improvement shown when taking MPH . RESULTS The proportion of children with learning disabilities who responded to MPH ( 55 % ) was significantly smaller ( chi(2)1 = 4.5 , p = 0.034 ) than the proportion of children without learning disabilities who responded adequately to MPH ( 75 % ) . This difference was mainly because of children with mathematics disability being particularly unresponsive to MPH ( chi(2)1 = 4.5 , p = 0.034 ) . Children with reading disability did not show this pattern of poor response ( chi(2)1 = 1.0 , p = 0.33 ) . CONCLUSION Children with ADHD and comorbid learning disability tended to respond more poorly to MPH . In particular , children with disability in mathematics responded less to MPH than those without disability in mathematics . Additional therapy may be indicated for this group of patients
Taken together , the studies pointed at substantial evidence for a negative association between ADHD symptoms and mathematical ability .
This association was particularly marked for the inattentive component of ADHD than for the hyperactive-impulsive component .
Evidence from twin studies also showed a significant genetic correlation between mathematics and ADHD , which was greater for the inattentive component of ADHD compared to the hyperactive-impulsive component .
Conclusions The differential relationship of the hyperactivity-impulsivity and inattention domains with mathematics emphasises the heterogeneity within the disorder and suggests a partially different aetiology of the two ADHD domains .
Background Several recent behavioural and behavioural genetic studies have investigated the relationship between attention deficit hyperactivity disorder ( ADHD ) and mathematical ability .
The aim of this systematic review was to provide an overview of these studies to date .
An emphasis was placed on review ing results that explored the association between mathematics and the two ADHD components of attention and hyperactivity-impulsivity separately .