A longitudinal examination of neuropsychological and clinical functioning in boys with attention deficit hyperactivity disorder (ADHD): improvements in executive functioning do not explain clinical improvement. Executive function and attention deficit hyperactivity disorder: stimulant medication and better executive function performance in children. Mediators of Methylphenidate Effects on Math Performance in Children with Attention-Deficit Hyperactivity Disorder Modafinil Improves Cognition and Attentional Set Shifting in Patients with Chronic Schizophrenia Dissecting the attention deficit hyperactivity disorder (ADHD) phenotype: Sustained attention, response variability and spatial attentional asymmetries in relation to dopamine transporter (DAT1) genotype Effects of Methylphenidate on Impulsive Responding in Children With Attention-Deficit Hyperactivity Disorder Slow oscillating transcranial direct current stimulation during non-rapid eye movement sleep improves behavioral inhibition in attention-deficit/hyperactivity disorder A Pilot Twin Study of Psychological Measures of Attention Deficit Hyperactivity Disorder A context for normalizing impulsiveness at work for adults with attention deficit/hyperactivity disorder (combined type).
BACKGROUND Attention deficit hyperactivity disorder ( ADHD ) often , but not always , persists into adulthood . Investigations of the associations between clinical and biological markers of persistence can shed light on causal pathways . It has been proposed that compensatory improvements in executive neuropsychological functioning are associated with clinical improvements . This is the first study to test this hypothesis prospect ively . METHOD The clinical and neuropsychological functioning of 17 boys with ADHD ( mean age 10.45 years at time 1 ; 14.65 years at time 2 ) and 17 typically developing ( TYP ) boys ( mean age 10.39 years at time 1 ; 14.47 years at time 2 ) was tested on two occasions , 4 years apart . This was done using a battery of st and ardized neuropsychological tests that included tasks with high and low executive dem and s. RESULTS Clinical improvements were observed over time . Neuropsychological performance improvements were also evident , with ADHD boys developing with a similar pattern to TYP boys , but with a developmental lag . Whilst there was an association between reduced symptoms and superior performance at retest for one task with a high executive dem and ( spatial working memory ) , this was not seen with two further high executive dem and tasks [ Stockings of Cambridge and intra-dimensional extra-dimensional ( ID/ED ) set shifting ] . Also , there was no association between change in executive functioning and change in symptoms . Baseline performance on the ID/ED set-shifting task predicted better clinical outcome . Only change in performance on the low executive dem and delayed matching-to- sample task predicted better clinical outcome . CONCLUSIONS These data highlight the importance of longitudinal measurements of cognition , symptoms and treatment response over time in children and adolescents with ADHD BACKGROUND Executive function deficits have been reported repeatedly in children with Attention Deficit Hyperactivity Disorder ( ADHD ) .  Stimulant medication has been shown to be effective in improving cognitive performance on most executive function tasks , but neuropsychological tests of executive function in this population have yielded inconsistent results . Method ological limitations may explain these inconsistencies . This study aim ed to measure executive function in medicated and non-medicated children with ADHD by using a computerized battery , the Cambridge Neuropsychological Test Automated Battery ( CANTAB ) , which is sensitive to executive function deficits in older patients with frontostriatal neurological impairments . METHODS Executive function was assessed in 30 children with ADHD : 15 were stimulant medication naive and 15 were treated with stimulant medication .  These two groups were compared to 15 age , sex and IQ matched controls . RESULTS The unmedicated children with ADHD displayed specific cognitive impairments on executive function tasks of spatial short-term memory , spatial working memory , set-shifting ability and planning ability . Impairments were also seen on spatial recognition memory and delayed matching to sample , while pattern recognition memory remained intact . The medicated children with ADHD were not impaired on any of the above executive function tasks except for deficits in spatial recognition memory . CONCLUSIONS ADHD is associated with deficits in executive function .  Stimulant medication is associated with better executive function performance . Prospect i ve follow-up studies are required to examine these effects Objective : Stimulant medications , such as methylpheni date ( MPH ) , improve the academic performance of children with attention-deficit hyperactivity disorder ( ADHD ) . However , the mechanism by which MPH exerts an effect on academic performance is unclear . We examined MPH effects on math performance and investigated possible mediation of MPH effects by changes in time on-task , inhibitory control , selective attention , and reaction time variability . Methods : Children with ADHD aged 7 to 11 years ( N = 93 ) completed a timed math worksheet ( with problems tailored to each individual 's level of proficiency ) and 2 neuropsychological tasks ( Go/No-Go and Child Attention Network Test ) at baseline , then participated in a 4-week , r and omized , controlled , titration trial of MPH . Children were then r and omly assigned to their optimal MPH dose or placebo for 1 week ( administered double-blind ) and repeated the math and neuropsychological tasks ( posttest ) . Baseline and posttest videorecordings of children performing the math task were coded to assess time on-task . Results : Children taking MPH completed 23 more math problems at posttest compared to baseline , whereas the placebo group completed 24 fewer problems on posttest versus baseline , but the effects on math accuracy ( percent correct ) did not differ . Path analyses revealed that only change in time on-task was a significant mediator of MPH 's improvements in math productivity . Conclusions : MPH-derived  math productivity improvements may be explained in part by increased time spent on-task , rather than improvements in neurocognitive parameters , such as inhibitory control , selective attention , or reaction time variability Modafinil , a novel cognitive enhancer , selectively improves neuropsychological task performance in healthy volunteers and adult patients with attention deficit hyperactivity disorder ( ADHD ) . It has been argued that persistent cognitive deficits in patients with schizophrenia are responsible for the failure of many patients to rehabilitate socially even when psychotic symptoms are in remission . The present study examined the potential of modafinil as a cognitive enhancer in schizophrenia . Twenty chronic patients with a diagnosis of schizophrenia were entered into a double-blind , r and omized , placebo-controlled crossover study using a 200 mg dose of modafinil . Modafinil had some cognitive enhancing properties in schizophrenia similar to those observed in healthy adults and adult patients with ADHD . Improvement was seen on short-term verbal memory span , with trends towards improved visual memory and spatial planning . This was accompanied by slowed response latency on the spatial planning task . No effect on stop-signal performance was seen . Importantly , significant improvement in attentional set shifting was seen , despite no effect of modafinil on this task being seen in healthy volunteers or ADHD patients . Modafinil may have potential as an important therapy for cognitive impairment in patients with schizophrenia , particularly because of its beneficial effects on attentional set shifting ADHD is a childhood-onset behavioural disorder with a heterogeneous profile of neuropsychological impairment . Neuropsychological heterogeneity may , in part , reflect underlying genetic differences . Here we examined sustained attention , response variability and spatial attentional asymmetries in a sample of children and adolescents with ADHD ( n=22 ) in relation to dopamine transporter genotype ( DAT1 ) and also controls ( n=20 ) . Participants performed the sustained attention to response task ( SART ) ( testing sustained attention and response variability ) and the greyscales task ( a perceptual measure of attentional bias ) . The latter has previously been shown to yield a robust leftward attentional asymmetry in healthy subjects . The 10-repeat allele of the DAT1 gene has been associated with ADHD in a number of studies and appears to have biological significance . The ADHD group was sub-divided into those individuals with two copies of the " high-risk " 10-repeat allele ( high-risk DAT1 ) versus those with one or no copies of this allele ( low-risk DAT1 ) . The high-risk DAT1 ADHD group displayed greater response variability on the SART than either the low-risk DAT1 group or healthy controls , whereas the latter two groups did not differ . Further , the high-risk DAT1 group showed an attenuated spatial asymmetry , relative to the low-risk DAT1 ADHD group , who showed the typical leftward attentional asymmetry . Our results suggest that the 10-repeat DAT1 allele may mediate neuropsychological impairment in ADHD . The application of molecular genetics may help to define neuropsychological impaired subgroups of ADHD 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 ) Background : Behavioral inhibition , which is a later-developing executive function ( EF ) and anatomically located in prefrontal areas , is impaired in attention-deficit and hyperactivity disorder ( ADHD ) . While optimal EFs have been shown to depend on efficient sleep in healthy subjects , the impact of sleep problems , frequently reported in ADHD , remains elusive . Findings of macroscopic sleep changes in ADHD are inconsistent , but there is emerging evidence for distinct microscopic changes with a focus on prefrontal cortical regions and non-rapid eye movement ( non-REM ) slow-wave sleep . Recently , slow oscillations ( SO ) during non-REM sleep were found to be less functional and , as such , may be involved in sleep-dependent memory impairments in ADHD . Objective : By augmenting slow-wave power through bilateral , slow oscillating transcranial direct current stimulation ( so-tDCS , frequency = 0.75 Hz ) during non-REM sleep , we aim ed to improve daytime behavioral inhibition in children with ADHD . Methods : Fourteen boys ( 10–14 years ) diagnosed with ADHD were included . In a r and omized , double-blind , cross-over design , patients received so-tDCS either in the first or in the second experimental sleep night . Inhibition control was assessed with a visuomotor go/no-go task .  Intrinsic alertness was assessed with a simple stimulus response task . To control for visuomotor performance , motor memory was assessed with a finger sequence tapping task . Results : SO-power was enhanced during early non-REM sleep , accompanied by slowed reaction times and decreased st and ard deviations of reaction times , in the go/no-go task after so-tDCS . In contrast , intrinsic alertness , and motor memory performance were not improved by so-tDCS . Conclusion : Since behavioral inhibition but not intrinsic alertness or motor memory was improved by so-tDCS , our results suggest that lateral prefrontal slow oscillations during sleep might play a specific role for executive functioning in ADHD There has been much interest in the genetics of attention deficit hyperactivity disorder and molecular genetic studies are now underway . The success of genetic studies will depend on how well the phenotype is defined . Twin studies using parent and teacher rated question naires or interviews all appear to yield highly heritable measures . Nevertheless , there is evidence to suggest that parent measures are subject to rater bias . Consequently there has been much interest in obtaining more objective measures of related traits such as attention span and impulsiveness using , computerised neuropsychological tasks . However there have been few twin studies examining the genetic contribution to these neuropsychological measures . The present study aims to investigate whether performance on the  Matching Familiar Figures Test ( MFFT ) and Continuous Performance Task ( CPT )  is genetically influenced in childhood . 20 monozygotic ( MZ ) and 20 dizygotic ( DZ ) twin pairs were r and omly selected from the Greater Manchester Twin Register . Preliminary data suggest that MZ twins perform more similarly than DZ twins on the MFFT , but not the CPT . Future work needs to examine whether other neuropsychological measures commonly used in research on ADHD are genetically influenced using larger twin sample Impaired executive function and impulsiveness or intolerance to boredom in adult attention deficit/hyperactivity disorder ( ADHD ) are thought to compromise performance at work . Several task parameters help people with ADHD to perform better on computerized cognitive tasks , namely reduced response-to-stimulus interval , discriminative feedback , or a format resembling a videogame . However , still very little is known about how these context s might be helpful in a real work environment . We developed a computerized task resembling a fast-paced videogame with no response-to-stimulus interval and constant and diverse discriminative error feedback . The task included several measurements of high-order executive function ( planning , working memory , and prospect i ve memory ) formatted as a single multitask simulating occupational activities ( SOA ) . We also administered the Continuous Performance Test-II ( CPT-II ) , a very simple vigilance task without discriminative feedback and with long response-to-stimulus intervals . We tested 30 adults answering to DSM-IV criteria of ADHD ( combined type ) and 30 IQ-matched adults without ADHD . As has been reported many times , the ADHD participants made significantly more errors of commission than the control participants on the CPT-II , whereas the two groups made the same number of errors of commission on the SOA . The ADHD group also sought discriminative feedback significantly more actively on the SOA than the control group and performed at par with the control group in all respects . There was no speed/accuracy trade-off , nor was there any evidence of other costs of normalization on the SOA . Impulsiveness in adult ADHD is compensable on a task simulating the work environment
Review of the evidence suggests that  task performance  may be useful in identifying individuals with ADHD at risk for academic impairment .
However , the evidence is less compelling for identifying youth at risk for impaired social functioning or poor health outcomes .
The review also found that task performance is likely useful for predicting response to treatment with methylpheni date .
Across studies , evidence indicated that interpreting task performance in an integrated manner , such as a factor score or mean score , was more consistently useful for predicting outcomes of interest than interpreting performance from a single task .
The role that neuropsychological task performance plays in the assessment of Attention-Deficit/Hyperactivity Disorder ( ADHD ) is currently ambiguous , and findings are mixed regarding whether tasks have validity for diagnosing the disorder .
Irrespective of their validity for diagnosing ADHD , neuropsychological tasks could provide valuable information to mental health professionals if they can inform recommendations for treatment targets and modalities .
Therefore , this review sought to synthesize the available evidence related to the use of neuropsychological task performance as a tool for informing treatment planning for youth with ADHD .
Review ed studies focused on examinations of associations between task performance and academic , social , and health outcomes , as well as response to treatment .