Executive function in children with Tourette syndrome and/or attention deficit hyperactivity disorder

Tourette Syndrome (TS) in children is associated with various neurobehavioral disorders including attention deficit hyperactivity disorder (ADHD). Children with TS and ADHD show some difficulties with neuropsychological tasks, but we do not know if children with TS alone have neuropsychological deficits. To assess specific cognitive differences among children with TS and/or ADHD, we administered a battery of neuropsychological tests, including 10 tasks related to executive function (EF), to 10 children with TS-only, 48 with ADHD-only, and 32 with TS + ADHD. Children in all groups could not efficiently produce output on a timed continuous performance task [Test of Variables of Attention (TOVA) mean reaction time and reaction time variability]. Children with TS-only appeared to have fewer EF impairments and significantly higher perceptual organization scores than children with TS + ADHD or ADHD-only. These findings suggest that deficiencies in choice reaction time and consistency of timed responses are common to all three groups, but children with TS-only have relatively less EF impairment than children with TS + ADHD or ADHD-only.     

Effects of reward and response costs on inhibition in ADHD children.

This study examined effects of reward and response costs on the ability of 19 attention-deficit hyperactivity disorder (ADHD) and 17 control children to inhibit responding. Children were tested under 4 reinforcement conditions on a go/no-go learning task developed by J. P. Newman, C. S. Widom, and S. Nathan (1985). Two conditions involved both reward and response costs, 1 response costs only, and 1 reward only. ADHD children made more commission errors than controls across the 4 conditions. Analyses of learning curves indicated that group differences became larger on later trials. Thus, impaired inhibition was more generalized in ADHD children than in the psychopaths and extraverts studied by Newman and colleagues, and it became most evident when the children were required to improve learning across trials. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Prenatal Alcohol Exposure Causes Attention Deficits in Male Rats.

Children with fetal alcohol spectrum disorder (FASD) are often diagnosed with attention-deficit/ hyperactivity disorder (ADHD). These children show increases in reaction time (RT) variability and false alarms on choice reaction time (CRT) tasks. In this study, adult rats prenatally exposed to ethanol were trained to perform a CRT task. An analysis of the distribution of RTs obtained from the CRT task found that rats with a history of prenatal ethanol exposure had more variable RT distributions, possibly because of lapses of attention. In addition, it was found that, similar to children with FASD, the ethanol-exposed rats had more false alarms. Thus, rats with prenatal ethanol exposure show attention deficits that are similar to those of children with FASD and ADHD. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Responsiveness of children with attention deficit–hyperactivity disorder to reward and response cost: Differential impact on performance and motivation.

Using a within-subject design and both high- and low-interest tasks, this study examined the effects of reward (R), response cost (RC), and no contingency (NR) on performance and motivation of 22 children with attention deficit–hyperactivity disorder (ADHD) and 22 controls. Dependent variables included performance measures, self-rated performance and motivation, and a new measure of behavioral motivation based on a 2-min postcontingency task. Both contingencies benefited some aspects of the performance of ADHD children; relative to R, RC showed stronger effects but at the expense of decreased self-rated motivation on the low-interest task. The performance of controls did not differ across tasks, whereas ADHD children performed relatively better on the high-interest task. Neither contingency decreased motivation measures relative to NR for either group. For ADHD children, motivational effects appeared to be influenced by self-perceptions of performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Identifying a distinctive familial frequency band in reaction time fluctuations in ADHD.

Objective: Patients with ADHD are typically more variable in their reaction times (RT) than control children. Signal processing analyses have shown that time series RT data of children with ADHD have a distinctive low frequency periodic structure suggestive of a pattern of occasional spontaneous performance lapses. Here we use a fine-grained analysis of spectral power across a broader frequency range to differentiate the periodic qualities of ADHD time series RT data from (a) 1/frequency noise, and (b) control performance. We also assess the familiality of these frequencies by using a proband-sibling design. Method: Seventy-one children with ADHD, one of their siblings, and 50 control participants completed a simple RT task. Power across the RT frequency spectrum was calculated. The frequencies significantly differentiating the two groups were identified. Familiality was assessed in two ways: first, by comparing probands with their unaffected siblings and controls, and, second, by investigating the siblings of neuropsychologically impaired and unimpaired children with ADHD. Results: Analyses converged to highlight the potential importance of the .20–.26 Hz band in differentiating the periodic structure of ADHD RT time series data from both 1/frequency noise and control performance. This frequency band also showed the strongest evidence of familiality. Conclusions: RT performance of children with ADHD had a distinctive periodic structure. The band identified as most differentiating and familial was at a higher frequency than in most previous reports. This highlights the importance of employing tasks with faster interstimulus intervals that will allow a larger portion of the frequency spectrum to be examined. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Selective effects of methylphenidate in attention deficit hyperactivity disorder: a functional magnetic resonance study

Functional MRI revealed differences between children with Attention Deficit Hyperactivity Disorder (ADHD) and healthy controls in their frontal-striatal function and its modulation by methylphenidate during response inhibition. Children performed two go/no-go tasks with and without drug. ADHD children had impaired inhibitory control on both tasks. Off-drug frontal-striatal activation during response inhibition differed between ADHD and healthy children: ADHD children had greater frontal activation on one task and reduced striatal activation on the other task. Drug effects differed between ADHD and healthy children: The drug improved response inhibition in both groups on one task and only in ADHD children on the other task. The drug modulated brain activation during response inhibition on only one task: It increased frontal activation to an equal extent in both groups. In contrast, it increased striatal activation in ADHD children but reduced it in healthy children. These results suggest that ADHD is characterized by atypical frontal-striatal function and that methylphenidate affects striatal activation differently in ADHD than in healthy children.     

A neuropsychological examination of the underlying deficit in attention deficit hyperactivity disorder: Frontal lobe versus right parietal lobe theories.

A neuropsychological approach was used to examine the frontal lobe and right parietal lobe theories of attention deficit hyperactivity disorder (ADHD). Considerable attempts were made to select as pure a group of ADHD boys as possible. The performance of 10-14-year-old ADHD boys (n?=?22), both on and off stimulant medication, was compared with the performance of non-ADHD control boys (n?=?22) on tasks purported to assess frontal lobe functioning (Stopping Task, Antisaccade Task, Tower of Hanoi) and right parietal lobe functioning (Visual-Spatial Cuing Task, Turning Task, Spatial Relations). Three important findings emerged: (a) unmedicated ADHD boys exhibited performance deficits on tasks in both frontal and parietal domains compared with control boys, (b) unmedicated ADHD boys appeared to be more severely impaired on the frontal tasks than on the parietal tasks, and (c) medicated ADHD boys performed better in both task domains compared with unmedicated ADHD boys. Several alternative interpretations of the results are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Working memory demands impair skill acquisition in children with ADHD.

This study examined the process of cognitive skill acquisition under differential working memory (WM) load conditions in children with the primarily inattentive (n = 21) and the combined (n = 32) subtypes of childhood attention-deficit/hyperactivity disorder (ADHD) and compared the results with those of non-ADHD controls (n = 48). Children completed 2 tasks of cognitive skill acquisition: alphabet arithmetic and finger math. The tasks differed in the amount of WM required for execution (alphabet arithmetic required more) but were otherwise matched with respect to logical structure, design, and discriminatory power. As would be predicted if the WM of the to-be-learned task affected the ability of children with ADHD to develop automaticity for a complex cognitive skill, ADHD-related impairments in the development of automaticity were seen for alphabet arithmetic but not for finger math. Results not only are relevant to ongoing debate regarding the presence of effortful versus automatic cognitive deficits in ADHD but also have implications for the development of new psychoeducational interventions for children with ADHD. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Evaluating the Endophenotype Model of ADHD Neuropsychological Deficit: Results for Parents and Siblings of Children With ADHD Combined and Inattentive Subtypes.

Neurogenetic models predict neuropsychological weaknesses in the relatives of children with attention-deficit/ hyperactivity disorder (ADHD). The authors examined executive and regulatory measures in 386 relatives (307 parents, 79 siblings) of children with ADHD combined type, ADHD inattentive type, and controls. Predicted deficits were seen on trailmaking (relatives of ADHD combined type only), stop-signal reaction times (relatives of girls only), and response variability (mothers only) but not on naming or output speed. Effects generally held, even with relatives' ADHD status controlled. A neuropsychologically impaired subgroup of children with ADHD had relatives with clear neuropsychological weaknesses. The authors conclude that a neurogenetic model of ADHD etiology is supportable only for a subset of executive functions and that neuropsychological heterogeneity warrants more examination in ADHD. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Levels of selective attention revealed through analyses of response time distributions.

The present research examines the nature of the interference effects in a number of selective attention tasks. All of these tasks result in interference in performance by presenting information that is irrelevant to task performance but competes for selection. The interference from this competing information slows the response time (RT) of participants relative to a condition where the competition is minimized. The authors use a convolution of an exponential and a Gaussian (ex-Gaussian) distribution to examine the influence of interference on the characteristics of RT distributions. Consistent with previous research, the authors show that interference in the Stroop task is reflected by both the Gaussian and exponential portions of the ex-Gaussian. In contrast, in 4 experiments they show that several other interference tasks evidence interference that is reflected only in the Gaussian portion of the ex-Gaussian distribution. The authors suggest that these differences reflect the operation of different selection mechanisms, and they examine how sequential sampling models accommodate these effects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Controlled Visuomotor Preparation Deficits in Attention-Deficit/Hyperactivity Disorder.

To the best of the authors' knowledge, there are no published reports on visuomotor preparation in attention-deficit/hyperactivity disorder (ADHD). This is unfortunate, because research suggests that ADHD is an output-related deficit, and suboptimal execution of tasks may be the result of incomplete visuomotor preparation. The authors compared 19 children with ADHD with 124 healthy and 120 pathological controls in terms of their performance (speed, speed variability, and accuracy) on the finger precuing test, a test measuring (automatic and controlled) visuomotor preparation. The data implied that children with ADHD have an impaired ability to engage in effortful, controlled visuomotor preparation activities. Fast, automatic response preparation was not affected by ADHD. In addition, children with ADHD showed more variability in overall test performance than other children. No group differences were found in response accuracy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of methylphenidate on complex cognitive processing in attention-deficit hyperactivity disorder.

Three experiments were conducted to explore the effects of methylphenidate (MPH), attention-deficit hyperactivity disorder (ADHD) diagnosis, and age on performance on a complex visual-memory search task. Results showed that the effects of MPH varied with information load. On low-processing loads, all doses of MPH helped children with ADHD to improve accuracy with no cost to reaction time (RT), whereas on high loads, higher MPH doses improved error rates while slowing RT. Without medication, children with ADHD showed high error rates and slow RTs across both low and high loads, as did younger, normal control children. Because MPH slowed performance on only the most difficult high-load conditions, it is argued that the drug improves self-regulatory ability, enabling children with ADHD to adapt differentially to high and low loads. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The psychological refractory period: Evidence for age differences in attentional time-sharing.

Reports 2 psychological refractory period (PRP) experiments in which the stimulus onset asynchrony (SOA) between Task 1 and 2 was 150, 250, 600, and 1,100 msec for both younger and older adults. H. Pashler's (1994) response-selection bottleneck theory predicts that SOA manipulations should not affect Task 1 performance, but that reaction time (RT) for Task 2 should increase as the SOA between the 2 tasks decreases (i.e., the classical PRP effect). In Exp 1, older adults showed a larger PRP effect, although Task 1 RT was affected by SOA, suggesting that Ss were grouping their responses on some trials. That is, Ss were holding their response for Task 1 until they had completed processing Task 2, and then they responded to both tasks almost simultaneously. However, a subset of Ss who showed no evidence of response grouping on Task 1 continued to show a larger PRP effect for older adults on Task 2. In Exp 2, older adults continued to show a larger PRP effect for Task 2, and Task 1 performance was unaffected by SOA. Findings provide evidence that older adults exhibit a decrement in time-sharing at the response-selection stage of processing. Results suggest that attentional time-sharing needs to be added to the list of topics examined in aging research on varieties of attention. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intellectual performance and school failure in children with attention deficit hyperactivity disorder and in their siblings.

Made psychiatric and intellectual assessments of 140 children with attention deficit hyperactivity disorder (ADHD), 120 normal controls, and their 303 siblings. The index children were White, non-Hispanic boys. ADHD children were more likely to have had learning disabilities, repeated grades, been placed in special classes, and received academic tutoring. They also did worse on the Wechsler Intelligence Scale for Children—Revised (WISC—R). Among ADHD probands, comorbid conduct, major depressive, and anxiety disorders predicted school placement more than school failure or WISC—R scores. However, the neuropsychological disability of all ADHD children could not be attributed to comorbid disorders because those without comorbidity had more school failure and lower WISC—R scores than normal controls. Intellectual impairment was also increased among siblings of ADHD children. This provides converging evidence that the ADHD syndrome is familial. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Concussion does not impact intraindividual response time variability.

This investigation examined the effect of concussion on intraindividual variability in 5 processing speed tasks. Forty-four adults, including 22 concussed and 22 healthy age- and gender-matched participants, completed the Headminder Concussion Resolution Index (D. M. Erlanger, D. J. Feldman, K. C. Kutner,& M. McCrea, 2001) twice. The test consists of a series of tasks including 25 trials of simple response time task, 70 trials of cued response time task (CuRT), 60 trials each for 2 visual recognition tasks, and 30 trials of symbol scanning task. Concussed participants completed a preinjury baseline assessment and were retested within 48 hours of injury diagnosis. The nonconcussed participants were retested 45 days after initial assessment. Average response time (RT), standard deviation, and response accuracy were calculated for each individual. Overall, concussed individuals had increased RTs across all tasks and were less accurate in the CuRT. RT variability for all tasks was elevated in concussed individuals, but controlling for mean RT at follow-up eliminated group differences. These findings indicate that response-time-variability increases in concussed individuals are proportional to processing-time increases. As such, RT variability is not a unique identifier of cognitive dysfunction following concussion. These results highlight that transient brain injury has significantly different neurobiological consequences than chronic conditions have. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Divided attention in youth-onset psychosis and attention deficit/hyperactivity disorder.

The authors used pupillary dilations to test whether divided attention deficits in youth-onset psychosis and attention deficit/hyperactivity disorder (ADHD) were because of limitations in recruitment of cognitive resources or abnormalities in attention allocation. Eight- to 19-year-olds with youth-onset psychosis or ADHD were administered a divided attention test consisting of an auditory digit span (DS) task and a simple visual response time (RT) task. In 4 conditions, participants performed neither (no task), 1 (DS or RT only), or both tasks (dual). Dependent variables were DS accuracy, RT, and pupillary dilation to digits as an estimate of recruitment of cognitive resources. The authors found no evidence for an abnormal attention strategy in either disorder. Instead, results were consistent with the hypothesis that both clinical groups have limitations in resource recruitment. These limitations were more severe in psychosis than in ADHD. Findings indicate that both clinical groups had difficulties in regulating physiological arousal on a moment-to-moment basis in accordance with task demands. Findings also demonstrate the importance of taking into account difficulties that constrain performance on simple tasks before interpreting impairments on complex tasks. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Learning disabilities and executive dysfunction in boys with attention-deficit/hyperactivity disorder.

The effect of comorbid reading or arithmetic learning disabilities (LDs) on neuropsychological function in attention-deficit/hyperactivity disorder (ADHD) was studied. Participants were young males diagnosed with ADHD, with and without LD, and non-ADHD, non-LD male controls of similar age. LD was defined by combined regression-based and low-achievement classifications. Analyses adjusted for the effect of psychiatric comorbidity, age, and socioeconomic status on neuropsychological function. Children who had both ADHD and LD were significantly more impaired on both executive and nonexecutive functions than ADHD children without LD. Neuropsychological performance was most impaired in ADHD with combined arithmetic and reading disability. These data indicate that comorbid LD, especially arithmetic disability, significantly increases the severity of executive function impairment in ADHD. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Does response variability predict distractibility among adults with attention-deficit/hyperactivity disorder?

Increased intraindividual variability in response time (RTSD) has been observed reliably in attention-deficit/hyperactivity disorder (ADHD) and has often been used as a measure of inattention. RTSD is assumed to reflect attentional lapses and distractibility, though evidence for the validity of this connection is lacking. We assessed whether RTSD is an indicator of inattention by comparing RTSD on the stop-signal task (SST) with performance on the delayed oculomotor response (DOR) task, a measure of distractibility. Participants included 30 adults with ADHD and 28 controls. Participants completed the SST and the DOR task, which measured subjects' ability to maintain attention and avoid distraction by inhibiting reflexive saccades toward distractors. On the SST, the ADHD group was slower to inhibit than were controls, indicating poorer inhibitory control in ADHD. The ADHD group also displayed slower reaction times (RTs), greater RTSD, and more omission errors. On the DOR task, the ADHD group displayed more premature saccades (i.e., greater distractibility) than did controls. Greater variability in RT was associated with increased distraction on the DOR task, but only in ADHD participants. Results suggest that RTSD is linked to distractibility among adults with ADHD and support the use of RTSD as a valid measure of inattention in ADHD. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Validity of DSM-IV attention-deficit/hyperactivity disorder for younger children

OBJECTIVE: Little is known about the validity of the diagnosis of attention-deficit/hyperactivity disorder (ADHD) in young children. Moreover, the results of the DSM-IV field trials raised concerns that inclusion of the new predominantly hyperactive-impulsive type of ADHD in DSM-IV might increase the likelihood of the diagnosis being given to active but unimpaired preschool and primary school children. METHOD: The validity of DSM-IV criteria for each subtype of ADHD was evaluated in 126 children, aged 4 through 6 years, and 126 matched comparison children. Probands and controls were classified by using structured diagnostic interviews of the parent and a DSM-IV checklist completed by the teacher. RESULTS: Children who met DSM-IV criteria for each subtype of ADHD according to parent and teacher reports differed consistently from controls on a wide range of measures of social and academic impairment, even when other types of psychopathology and other potential confounds were controlled. CONCLUSIONS: When diagnosed by means of a structured diagnostic protocol, all three DSM-IV subtypes of ADHD are valid for 4- through 6-year-old children in the sense of identifying children with lower mean scores on measures of adaptive functioning that are independently associated with ADHD.     

Executive functions, information sampling, and decision making in narcolepsy with cataplexy.

Objective: Narcolepsy with cataplexy (NC) affects neurotransmitter systems regulating emotions and cognitive functions. This study aimed to assess executive functions, information sampling, reward processing, and decision making in NC. Method: Twenty-one NC patients and 58 healthy participants performed an extensive neuropsychological test battery. Results: NC patients scored as controls in executive function tasks assessing set shifting, reversal learning, working memory, and planning. Group differences appeared in a task measuring information sampling and reward sensitivity. NC patients gathered less information, tolerated a higher level of uncertainty, and were less influenced by reward contingencies than controls. NC patients also showed reduced learning in decision making and had significantly lower scores than controls in the fifth block of the IOWA gambling task. No correlations were found with measures of sleepiness. Conclusions: NC patients may achieve high performance in several neuropsychological domains, including executive functions. Specific differences between NC patients and controls highlight the importance of the hypocretin system in reward processing and decision making and are in line with previous neuroimaging and neurophysiological studies. (PsycINFO Database Record (c) 2011 APA, all rights reserved)