The effects of co‐occurring ADHD symptoms on electrophysiological correlates of cognitive control in young people with Tourette syndrome

Efficient cognitive control is implicated in tic control in young people with Tourette syndrome (TS). Attention‐deficit/hyperactivity disorder (ADHD) frequently co‐occurs with TS and is associated with impaired cognitive control. Young people with TS and ADHD (TS+ADHD) show poorer cognitive control performance than those with TS, but how co‐occurring ADHD affects underlying neural activity is unknown. We investigated this issue by examining behavioural and event‐related potential (ERP) correlates of cognitive control in young people with these conditions. Participants aged 9–17 with TS (n = 17), TS+ADHD (n = 17), ADHD (n = 11), and unaffected controls (n = 20) performed a visual Go/Nogo task during electroencephalography (EEG) recording. Behavioural performance measures (D‐prime, RT, reaction time variability, post‐error slowing) and ERP measures (N2, P3, error‐related negativity (ERN), error positivity (Pe)) were analysed in a 2 (TS‐yes, TS‐no) × 2 (ADHD‐yes, ADHD‐no) factorial analysis to investigate the effects of TS, ADHD, and their interaction. The results of these analyses showed that ADHD was associated with poorer performance and reduced amplitude of all ERPs, reflecting widespread cognitive control impairments. Tourette syndrome was associated with slowed RTs, which might reflect a compensatory slowing of motor output to facilitate tic control. There was no interaction between the TS and ADHD factors for any behavioural or ERP measure, indicating the impairing effects of ADHD on behaviour and electrophysiological markers of cognitive control were present in TS+ADHD and that RT slowing associated with TS was unaffected by co‐occurring ADHD symptoms.     

Motor excitability during movement preparation in Tourette syndrome

Tourette syndrome (TS) is a neurodevelopmental disorder characterized by the occurrence of motor and vocal tics. TS has been linked to the impaired operation of cortical‐striatal‐thalamic‐cortical circuits that give rise to hyper‐excitability of cortical motor areas, which may be exacerbated by dysfunctional intra‐cortical inhibitory mechanisms. That said, many individuals gain control over their tics during adolescence and it has been suggested that this increased control arises as a result of the development of mechanisms that operate to suppress corticospinal excitability (CSE) ahead of volitional movements. Here we used single‐pulse transcranial magnetic stimulation (TMS) in conjunction with a manual Go/NoGo task to investigate alterations in CSE ahead of volitional movements in a group of adolescents with TS (N = 10). Our study demonstrated that CSE, as measured by TMS‐induced motor‐evoked potentials (MEPs), was significantly reduced in the TS group in the period immediately preceding a finger movement. More specifically, we show that individuals with TS, unlike their age‐matched controls, do not exhibit the predicted increase in mean MEP amplitude and decrease in MEP variability that immediately precede the execution of volitional movements in typically developing young adults. Finally, we report that the magnitude of the rise in MEP amplitude across the movement preparation period in TS is significantly negatively correlated with clinical measures of motor tic severity, suggesting that individuals with severe motor tics are least able to modulate motor cortical excitability.     

Implicit sequence learning in young people with Tourette syndrome with and without co-occurring attention-deficit/hyperactivity disorder

Impaired habit-learning has been proposed to underlie the tic symptoms of Tourette syndrome (TS). However, accounts differ in terms of how habit-learning is altered in TS, with some authors proposing habit formation is impaired due to a deficient ‘chunking’ mechanism, and others proposing habit-learning is overactive and tics reflect hyperlearned behaviours. Attention-deficit/hyperactivity disorder (ADHD) frequently co-occurs with TS and is known to affect cognitive function in young people with co-occurring TS and ADHD (TS + ADHD). It is unclear, however, how co-occurring ADHD symptoms affect habit-learning in TS. In this study, we investigated whether young people with TS would show deficient or hyperactive habit-learning, and assessed the effects of co-occurring ADHD symptoms on habit-learning in TS. Participants aged 9–17 years with TS (n = 18), TS + ADHD (n = 17), ADHD (n = 13), and typical development (n = 20) completed a motor sequence learning task to assess habit-learning. We used a 2 (TS-yes, TS-no) × 2 (ADHD-yes, ADHD-no) factorial analysis to test the effects of TS, ADHD, and their interaction on accuracy and reaction time indices of sequence learning. TS was associated with intact sequence learning, but a tendency for difficulty transitioning from sequenced to non-sequenced performance was suggestive of hyper-learning. ADHD was associated with significantly poorer accuracy during acquisition of the sequence, indicative of impaired habit-learning. There were no interactions between the TS and ADHD factors, indicating young people with TS + ADHD showed both TS- and ADHD-related atypicalities in habit-learning.     

Effects of emotional response on the Stroop‐like task in preschool children and young adults

This study investigated the effects of emotional response on an inhibitory task, the Stroop‐like day‐night task, in which participants are presented with two pictures. They are then requested to inhibit naming what the card shown to them represents and instead state what the other card represents. Specifically, 35 4‐ to 6‐year‐old children and 15 young adults were administered the emotion‐related happy‐sad task and the emotion‐unrelated up‐down task using the same stimulus set (happy and sad cartoon faces). The results suggested that vulnerability to errors in the happy‐sad task was not derived from increased inhibitory demand. The results also suggested that the happy‐sad task is more inhibitory‐demanding in terms of response time. These results suggested that the happy‐sad task elicits interference more than other variants of this task, not because the task involves emotional stimuli per se but because the task involves both emotional stimuli and emotional responses.     

The lived experiences of individuals with Tourette syndrome or tic disorders: A meta‐synthesis of qualitative studies

There is a growing body of qualitative literature describing the lived experiences of people with tic disorders (TDs). The aim of this paper was to conduct a systematic review of this literature, synthesizing the perspectives of individuals on their experiences. Meta‐synthesis methodology was utilized to review and draw together findings from 10 articles, from which key concepts were extracted, and over‐arching themes generated. Six themes were identified to encompass the experience of TDs, including (1) cultural, semantic issues of the condition; (2) negative experiences in organizations and treatment; (3) the value and negative impact on interpersonal relationships; (4) personal identity in the constant presence of TDs; (5) concerns for the future; and (6) strategies to control and manage the observable presence of tics. Adaptive coping strategies were found to encompass continuous social adaptation, strategies to manage tics and social perceptions, self‐acceptance, advocacy, and support from others. The results highlighted the significant role of social and cultural issues related to understanding and stigma, which underpinned many of the lived experiences. Implications for clinical practice in supporting individuals with TDs were also highlighted.     

Premonitory urges are associated with decreased grey matter thickness within the insula and sensorimotor cortex in young people with Tourette syndrome

Tourette syndrome (TS) is a neurological disorder characterized by vocal and motor tics and is associated with cortical–striatal–thalamic–cortical circuit (CSTC) dysfunction and hyperexcitability of cortical limbic and motor regions, which are thought to lead to the occurrence of tics. Importantly, individuals with TS often report that their tics are preceded by ‘premonitory sensory phenomena’ (PSP) that are described as uncomfortable cognitive or bodily sensations that precede the execution of a tic, and are experienced as a strong urge for motor discharge. While the precise role played by PSP in the occurrence of tics is controversial, PSP are nonetheless of considerable theoretical and clinical importance in TS, not least because they form the core component in many of the behavioural therapies that are currently used in the treatment of tic disorders. In this study, we investigated the brain structure correlates of PSP. Specifically, we conducted a whole‐brain analysis of cortical (grey matter) thickness in 29 children and young adults with TS and investigated the association between grey matter thickness and PSP. We demonstrate for the first time that PSP are inversely associated with grey matter thickness measurements within the insula and sensorimotor cortex. We also demonstrate that grey matter thickness is significantly reduced in these areas in individuals with TS relative to a closely age‐ and gender‐matched group of typically developing individuals and that PSP ratings are significantly correlated with tic severity.     

Interference control in preschoolers: factors influencing performance on the day–night task

Two experiments investigated preschoolers' interference control in variants of the day–night task. The day–night task involves instructing children across 16 trials to say the word ‘day’ when viewing a card depicting a nighttime sky and to say ‘night’ when shown a picture of the daytime sky. The purpose of the experiments was to investigate whether the depiction on each card distracts children because it is semantically associated with the instructed response or because the depicted item cues the alternative (incorrect) response within the response set. The results in the first study (N=23, M=52.65 months) and second study (N=54, M=50.81 months) indicate that a close semantic relation between the picture and the target response does not pose substantial interference for preschoolers. In contrast, the pictured item poses a significant challenge for preschoolers when it depicts the interfering alternative in the response set. Theoretical implications of these results for the development of interference control are discussed. Copyright © 2008 John Wiley & Sons, Ltd.     

Performance on Stroop‐like assessments of inhibitory control by 4‐ and 5‐year‐old children

The rapid development of an aspect of executive functioning (EF), inhibitory control (IC), between the ages of 3‐ and 5‐years, leads to an increase in a child's capacity to suppress inappropriate responding and therefore activate the necessary resources to carry‐out goal‐directed activity (Psychological Bulletin, 1997, 121 , 65–94). To measure EF in children, tasks administered clinically to adults are adapted. The Day–Night Stroop (DNS) is a pictorial modification of the Stroop Test (Journal of Experimental Psychology, 1935, 18 , 642–662), developed for pre‐literate children. Although suitable as a measure of IC in 3‐ to 4‐year‐old children, ceiling effects have been reported on the DNS in slightly older preschoolers. The present study attempted to overcome this limitation by examining the suitability of two modified versions of the DNS in 4‐ to 5‐year‐old preschoolers. To investigate the executive demands made by both Stroop‐like tasks, their associations with another measure of IC (stop‐signal task) and a measure of working memory were examined. Counter to expectations, no significant association was found in performance between the two Stroop‐like tasks; however, the modified DNS developed in this study showed significant relationships with the other executive tasks. The results are discussed in relation to the different methodologies used by these Stroop measures. Implications of this study suggest that researchers should consider more test‐specific factors when assessing EF in young children. Copyright © 2010 John Wiley & Sons, Ltd.     

Cognitive deficits of executive functions and decision‐making in obsessive‐compulsive disorder

The nature of cognitive deficits in obsessive‐compulsive disorder (OCD) is characterized by contradictory findings in terms of specific neuropsychological deficits. Selective impairments have been suggested to involve visuospatial memory, set shifting, decision‐making and response inhibition. The aim of this study was to investigate cognitive deficits in decision‐making and executive functioning in OCD. It was hypothesized that the OCD patients would be less accurate in their responses compared to the healthy controls in rational decision‐making on a version of the Cambridge gambling task (CGT) and on the color‐word interference test and on a version of the Tower of Hanoi test (tower test) of executive functioning. Thirteen participants with OCD were compared to a group of healthy controls (n = 13) matched for age, gender, education and verbal IQ. Results revealed significant differences between the OCD group and the healthy control group on quality of decision‐making on the CGT and for achievement score on the tower test. On these two tasks the OCD group performed worse than the healthy control group. The symptom‐dimension analysis revealed performance differences where safety checking patients were impaired on the tower test compared to contamination patients. Results are discussed in the framework of cognition and emotion processing and findings implicate that OCD models should address, specifically, the interaction between cognition and emotion. Here the emotional disruption hypothesis is forwarded to account for the dysfunctional behaviors in OCD. Further implications regarding methodological and inhibitory factors affecting cognitive information processing are highlighted.     

Associations between violence,criminality, and cognitive control deficits among young men living in low resource communities in South Africa

Despite empirical support for “Self-control theory” in criminology, there is controversy about how self-control should be operationalized. Working within the framework of “self-control theory,” we investigated if violence and criminal behaviors are associated with nine distinct dimensions of cognitive control in a community sample of young men (n = 654) living in peri-urban townships in South Africa. Cognitive control was assessed using the Behavior Rating Inventory of Executive Function. Multivariate statistical analysis was used, to identify associations between violence and criminality, and deaggregated measures of nine distinct components of cognitive control. Fifteen percent of the sample reported recent violence, 27% had been in physical fights with family/friends in the preceding 6 months, 10% reported being arrested, 4% reported forced sexual contact, and 26% reported intimate partner violence (IPV). Controlling for substance use and sociodemographic variables, contact with the criminal justice system and violence were associated with deficits in all domains of cognitive control. Forced sexual contact was associated with behavioral dysregulation. IPV was associated with behavior dysregulation and executive control dysfunction. Future studies might utilize deaggregated measures of self-control to provide further insight into links between particular components of cognitive control and various forms of offending and violence.     

Visual‐motor and executive functions in children born preterm: The Bender Visual Motor Gestalt Test revisited

Böhm, B., Lundequist, A. & Smedler, A.‐C. (2010). Visual‐motor and executive functions in children born preterm: The Bender Visual Motor Gestalt Test revisited. Scandinavian Journal of Psychology, 51, 376–384. Visual‐motor development and executive functions were investigated with the Bender Test at age 5½ years in 175 children born preterm and 125 full‐term controls, within the longitudinal Stockholm Neonatal Project. Assessment also included WPPSI‐R and NEPSY neuropsychological battery for ages 4–7 ( Korkman, 1990 ). Bender protocols were scored according to Brannigan & Decker (2003) , Koppitz (1963) and a complementary neuropsychological scoring system (ABC), aimed at executive functions and developed for this study. Bender results by all three scoring systems were strongly related to overall cognitive level (Performance IQ), in both groups. The preterm group displayed inferior visual‐motor skills compared to controls also when controlling for IQ. The largest group differences were found on the ABC scoring, which shared unique variance with NEPSY tests of executive function. Multiple regression analyses showed that hyperactive behavior and inattention increased the risk for visual‐motor deficits in children born preterm, whereas no added risk was seen among hyperactive term children. Gender differences favoring girls were strongest within the preterm group, presumably reflecting the specific vulnerability of preterm boys. The results indicate that preterm children develop a different neurobehavioral organization from children born at term, and that the Bender test with a neuropsychological scoring is a useful tool in developmental screening around school start.     

Equivalence‐based instruction to establish a textual activity schedule in an adult with Down syndrome

Transfer of control from picture to text‐based activity schedules has been shown to occur following conditional discrimination training in children with autism. This study extended this research by evaluating if conditional discrimination training could promote transfer of control in an adult with Down syndrome. The participant was taught to select photographs and pictures of kitchen tools when provided with dictated names. Then, he completed a text‐based activity schedule, matched printed words to photographs, and orally named printed words without direct training.     

Bilingualism,executive control,and age at diagnosis among people with early‐stage Alzheimer's disease in Wales

The observation of a bilingual advantage in executive control tasks involving inhibition and management of response conflict suggests that being bilingual might contribute to increased cognitive reserve. In support of this, recent evidence indicates that bilinguals develop Alzheimer's disease (AD) later than monolinguals, and may retain an advantage in performance on executive control tasks. We compared age at the time of receiving an AD diagnosis in bilingual Welsh/English speakers (n = 37) and monolingual English speakers (n = 49), and assessed the performance of bilinguals (n = 24) and monolinguals (n = 49) on a range of executive control tasks. There was a non‐significant difference in age at the time of diagnosis, with bilinguals being on average 3 years older than monolinguals, but bilinguals were also significantly more cognitively impaired at the time of diagnosis. There were no significant differences between monolinguals and bilinguals in performance on executive function tests, but bilinguals appeared to show relative strengths in the domain of inhibition and response conflict. Bilingual Welsh/English speakers with AD do not show a clear advantage in executive function over monolingual English speakers, but may retain some benefits in inhibition and management of response conflict. There may be a delay in onset of AD in Welsh/English bilinguals, but if so, it is smaller than that found in some other clinical populations. In this Welsh sample, bilinguals with AD came to the attention of services later than monolinguals, and reasons for this pattern could be explored further.     

Cognitive control in belief‐laden reasoning during conclusion processing: An ERP study

Belief bias is the tendency to accept conclusions that are compatible with existing beliefs more frequently than those that contradict beliefs. It is one of the most replicated behavioral findings in the reasoning literature. Recently, neuroimaging studies using functional magnetic resonance imaging (fMRI) and event‐related potentials (ERPs) have provided a new perspective and have demonstrated neural correlates of belief bias that have been viewed as supportive of dual‐process theories of belief bias. However, fMRI studies have tended to focus on conclusion processing, while ERPs studies have been concerned with the processing of premises. In the present research, the electrophysiological correlates of cognitive control were studied among 12 subjects using high‐density ERPs. The analysis was focused on the conclusion presentation phase and was limited to normatively sanctioned responses to valid–believable and valid–unbelievable problems. Results showed that when participants gave normatively sanctioned responses to problems where belief and logic conflicted, a more positive ERP deflection was elicited than for normatively sanctioned responses to nonconflict problems. This was observed from ?400 to ?200 ms prior to the correct response being given. The positive component is argued to be analogous to the late positive component (LPC) involved in cognitive control processes. This is consistent with the inhibition of empirically anomalous information when conclusions are unbelievable. These data are important in elucidating the neural correlates of belief bias by providing evidence for electrophysiological correlates of conflict resolution during conclusion processing. Moreover, they are supportive of dual‐process theories of belief bias that propose conflict detection and resolution processes as central to the explanation of belief bias.     

Associations of physical activity and gross motor skills with executive function in preschool children from low‐income South African settings

Executive function is foundational for cognitive development. Previous research has shown both gross motor skills and physical activity to be related to executive function. However, evidence for these relationships in the preschool years, as well as in low‐ and middle‐income countries is lacking. Therefore, this study aimed to investigate the relationships between components of executive function (inhibition, shifting and working memory) and gross motor skills (locomotor skills and object control skills) in a sample of preschool children from urban and rural low‐income settings in South Africa. Results revealed that inhibition and working memory, but not shifting, were associated with gross motor skills. More specifically: inhibition was associated with both locomotor [β = 0.20, p = 0.047] and object control skills [β = 0.24, p = 0.024], whereas working memory was only associated with locomotor skills [β = 0.21, p = 0.039]. Physical activity was not associated with inhibition and shifting but was negatively associated with working memory. These results elaborate a growing evidence base linking executive function and gross motor skills in the early years, and it is the first to look at specific associations of locomotor and object control skills with executive function in the South African context (a low‐ and middle‐income country).