Evoked Potentials Differentiate Developmental Coordination Disorder From Attention-Deficit/Hyperactivity Disorder in a Stop-Signal Task: A Pilot Study

Does the stop-signal P3 reflect inhibitory control?

The ability to stop already-initiated actions is paramount to adaptive behavior. In psychology and neuroscience alike, action-stopping is a popular model behavior to probe inhibitory control - the underlying cognitive control process that is purportedly vital to regulating thoughts and actions. Starting with seminal work in the 1990s, the frontocentral stop-signal P3 - an event-related potential derived from scalp EEG - has been proposed as a neurophysiological index of inhibitory control during action-stopping. However, this association has been challenged repeatedly over recent years. Here, we perform a critical review of both the evidence in support of the association between this P3 index and inhibitory control, as well as its documented criticisms. We first comprehensively review literature from the past three decades that suggested a link between stop-signal P3 and inhibitory control. Second, we then replicate the key empirical patterns reported in that body of literature in a uniquely large stop-signal task EEG dataset (N = 255). Third, we then examine the criticisms raised against the view of P3 as an index of inhibitory control and evaluate the evidence supporting these arguments. Finally, we present an updated view of the process(es) reflected in the stop-signal P3. Specifically, we propose that the stop-signal P3 indexes a specific, selective inhibitory control process that critically contributes to action-stopping. This view is motivated by recent two-stage models of inhibitory control and emerging empirical data. Together, we hope to clarify the process(es) reflected in the stop-signal P3 and resolve the ongoing debates regarding its utility as an index of inhibitory control during action-stopping.

Investigating the Mediating Role of Executive Function in the Relationship Between ADHD and DCD Symptoms and Depression in Adults

This study was designed to test the effects of Attention Deficit Hyperactivity Disorder (ADHD) and Developmental Co-ordination Disorder (DCD) on depression levels and investigate the mediating role of executive function (EF) in adults. Adults with ADHD, DCD, and ADHD + DCD (N = 139) completed self-report measures of ADHD, DCD, depression, and EF. There were distinct profiles of EF across diagnostic groups, and higher depression symptoms in adults with ADHD + DCD than DCD alone. All EF domains were predicted by ADHD symptoms, and several by DCD symptoms. ADHD and DCD symptoms, and most EF domains, predicted depression symptoms. Overall EF difficulties fully mediated the relationships between ADHD/DCD and depression symptoms. Several specific EF domains relating to behavioural regulation and metacognition also showed full/partial mediating effects. The mediating role of EF difficulties between these neurodevelopmental conditions and depression symptoms has implications for their understanding and treatment, suggesting that targeting EF may be important for preventing co-occurring depression.

Action-outcome Regularity Perceptual Sensitivity in Children with Developmental Coordination Disorder

PURPOSE

An internal model deficit is considered to underlie developmental coordination disorder (DCD); thus, children with DCD have an altered sense of agency (SoA), which is associated with depressive symptoms. Furthermore, the perception of action-outcome regularity is present in early development, is involved in the generation of SoA, and has roles in adaptive motor learning and coordinated motor skills. However, perceptual sensitivity to action-outcome regularity has not been examined in children with DCD.

METHODS

We investigated perceptual sensitivity to action-outcome regularity in 6-15-year-old children with DCD and age- and sex-matched typically developing (TD) children. Both groups were assessed for coordinated motor skills with the Movement Assessment Battery for Children-2nd Edition, while the DCD group was assessed with the DCD Questionnaire, Social Communication Questionnaire, Attention-Deficit/Hyperactivity Disorder-Rating Scale, and Depression Self- Rating Scale for Children.

RESULTS

Perceptual sensitivity to action-outcome regularity was significantly reduced in children with DCD. However, there was a significant correlation between perceptual sensitivity to action-outcome regularity and age in DCD and TD children. Perceptual sensitivity to action-outcome regularity was significantly lower in younger children with DCD than in younger and older TD children, but there were no significant differences between older children with DCD and younger and older TD children.

CONCLUSION

The current results suggest that children with DCD have significantly reduced perceptual sensitivity to action-outcome regularity at younger ages, which may alter SoA and inhibit internal model development, thereby reducing motor skill coordination.

Exploring adults' recollections of growing up with childhood motor difficulties: a qualitative study using systematic text condensation

OBJECTIVE

To explore the ramifications of childhood motor difficulties, providing insights into their impact and consequences over time.

DESIGN

A qualitative study using semistructured individual interviews. Data were analysed using systematic text condensation.

SETTING

Neonatal intensive care recipients born at Uppsala University Children's Hospital, Uppsala, Sweden, between 1986 and 1989, were enrolled in a longitudinal follow-up study and subsequently interviewed in 2019-2020.

PARTICIPANTS

13 individuals in their early 30s, who met the criteria for developmental coordination disorder or performed below the 5th percentile on motor tests at 6.5 years of age, were interviewed. Those with co-occurring deficits in attention or social behavioural at age 6.5 were excluded.

RESULTS

Two themes emerged: (1) lifelong challenges and (2) navigating the journey of motor difficulties: support, awareness and confidence. Five participants reported persistent motor difficulties. They adapted and integrated these challenges into their daily lives without feeling constrained. Parental support was crucial to their success, whereas support from schools was limited.

CONCLUSION

Adults who faced motor difficulties in childhood developed effective coping strategies, overcame challenges and now lead fulfilling lives. The findings stress the importance of parental support and understanding, addressing contextual factors and fostering positive attitudes and supportive environments to enhance well-being and participation.

Assessing Inhibitory Control Deficits in Adult ADHD: A Systematic Review and Meta-analysis of the Stop-signal Task

In recent years, there has been an increasing quest in improving our understanding of the neurocognitive deficits underlying adult attention-deficit/hyperactivity disorder (ADHD). Current statistical manuals of psychiatric disorders emphasize inattention and hyperactivity-impulsivity symptoms, but empirical studies have also shown consistent alterations in inhibitory control. To date, there is no established neuropsychological test to assess inhibitory control deficits in adult ADHD. A common paradigm for assessing response inhibition is the stop-signal task (SST). Following PRISMA-selection criteria, our systematic review and meta-analysis integrated the findings of 26 publications with 27 studies examining the SST in adult ADHD. The meta-analysis, which included 883 patients with adult ADHD and 916 control participants, revealed reliable inhibitory control deficits, as expressed in prolonged SST response times, with a moderate effect size g = 0.51 (95% CI: 0.376-0.644, p < 0.0001). The deficits were not moderated by study quality, sample characteristics or clinical parameters, suggesting that they may be a phenotype in this disorder. The analyses of secondary outcome measures revealed greater SST omission errors and reduced go accuracy in patients, indicative of altered sustained attention. However, only few (N < 10) studies were available for these measures. Our meta-analysis suggests that the SST, in conjunction with other tests and questionnaires, could become a valuable tool for assessing inhibitory control deficits in adult ADHD.

EEG spectral power in developmental coordination disorder and attention-deficit/hyperactivity disorder: a pilot study

Developmental coordination disorder (DCD) and attention-deficit/hyperactivity disorder (ADHD) overlap in symptoms and often co-occur. Differentiation of DCD and ADHD is crucial for a better understanding of the conditions and targeted support. Measuring electrical brain activity with EEG may help to discern and better understand the conditions given that it can objectively capture changes and potential differences in brain activity related to externally measurable symptoms beneficial for targeted interventions. Therefore, a pilot study was conducted to exploratorily examine neurophysiological differences between adults with DCD and/or ADHD at rest. A total of N = 46 adults with DCD (n = 12), ADHD (n = 9), both DCD + ADHD (n = 8), or typical development (n = 17) completed 2 min of rest with eyes-closed and eyes-open while their EEG was recorded. Spectral power was calculated for frequency bands: delta (0.5-3 Hz), theta (3.5-7 Hz), alpha (7.5-12.5 Hz), beta (13-25 Hz), mu (8-13 Hz), gamma (low: 30-40 Hz; high: 40-50 Hz). Within-participants, spectral power in a majority of waveforms significantly increased from eyes-open to eyes-closed conditions. Groups differed significantly in occipital beta power during the eyes-open condition, driven by the DCD versus typically developing group comparison. However, other group comparisons reached only marginal significance, including whole brain alpha and mu power with eyes-open, and frontal beta and occipital high gamma power during eyes-closed. While no strong markers could be determined to differentiate DCD versus ADHD, we theorize that several patterns in beta activity were indicative of potential motor maintenance differences in DCD at rest. Therefore, larger studies comparing EEG spectral power may be useful to identify neurological mechanisms of DCD and continued differentiation of DCD and ADHD.

Roadside experiences of parents of children with developmental coordination disorder and/or attention deficit hyperactivity disorder

Introduction

Pedestrians are a vulnerable group at the roadside and previous research has identified that children with DCD and ADHD are at a heightened risk of pedestrian injuries. Despite this, limited research has explored parental perspectives of the pedestrian risks faced by children with DCD and/or ADHD. Understanding parents' perspectives provides a unique insight into the challenges children face every day and the concerns that parents perceive regarding their children's safety as pedestrians. Therefore, the aim of this study was to explore parents' perspectives of the pedestrian risks faced by their children with DCD and/or ADHD.

Methods

Semi-structured interviews were conducted with 14 parents of primary school and early secondary school aged children with age range 7-17. The participants were divided into three groups based on their children's conditions: DCD group (10-17 years, n = 3), ADHD group (7-13 years, n = 5), and co-occurring group (7-16 years, n = 6). All parents confirmed an existing diagnosis and completed the SNAP-IV and DCDQ as screening tools. The interviews explored parents' perspectives regarding their children's pedestrian behaviors, parents' concerns and preventative measures taken to improve the pedestrian safety of their children with DCD and/or ADHD. Reflexive thematic analysis was undertaken to analyze the interviews, from which three themes were developed.

Results

The first theme related to the challenges experienced by children at the roadside; parents emphasized the significance of structured and controlled pedestrian crossing sites, underlining their preference for designated crossings as safer options due to their heightened perceptions of risk associated with other road-crossing locations. The second theme: parental concerns and influences on children's road safety referred to their children's performance and safety at the roadside, leading to increased monitoring and a more protective approach to road crossing. The third theme: road safety education related to various strategies parents implemented to mitigate risks, while balancing independence and prioritizing their safety.

Discussion

While there were commonalities in the challenges faced by children with DCD and/or ADHD at the roadside, there were also notable differences. Parents of children with DCD discussed challenges with spatial awareness and motor skills, whereas parents of children with ADHD discussed challenges with impulsivity and inattention. Parents of children with co-occurring DCD and ADHD described a complex interplay of these challenges. It is evident from the interviews that children with DCD and/or ADHD require a distinct approach to develop their pedestrian skills effectively and parents reported specific strategies they used to address the risks associated with their children's roadside behavior. Promoting pedestrian safety for children with DCD and/or ADHD necessitates collaboration among parents, schools and local authorities to implement comprehensive measures ensuring their safety. These findings contribute to understanding parental experiences and needs, providing valuable guidance for targeted interventions and policies to enhance the road safety of children with DCD and/or ADHD.

Impact of developmental coordination disorder in childhood on educational outcomes in adulthood among neonatal intensive care recipients: a register-based longitudinal cohort study

OBJECTIVES

Developmental coordination disorder (DCD) is related to poorer educational outcomes among children and adolescents. Evidence on this association into adulthood is lacking. Therefore, we aimed to investigate whether probable DCD (pDCD) in childhood affected educational outcomes among adults, and whether this was affected by sex or a co-occurring attention deficit in childhood.

DESIGN

Register-based longitudinal cohort study.

SETTING

Neonatal intensive care (NIC) recipients born at Uppsala University Children's Hospital, Uppsala, Sweden, from 1986 to 1989 until they reached the age of 28.

PARTICIPANTS

185 NIC recipients.

PRIMARY AND SECONDARY OUTCOME MEASURES

At the age of 6.5, 46 (24.6%) of the NIC recipients were diagnosed with pDCD. Using register-based longitudinal data, we compared participants with and without pDCD in terms of: (1) age at Upper Secondary School (USS) graduation, and (2) highest level of education achieved by age 28.

RESULTS

The median age at USS graduation was 19 years, with similar graduation ages and ranges between those with or without pDCD. However, a higher proportion of participants without pDCD had graduated from USS at ages 19 and 24. By age 29, most participants had completed USS. At age 28, 33% of participants had attained a bachelor's or master's degree. Although there was no significant difference between the groups, the proportion that had attained a degree was higher among those without pDCD and women without pDCD had achieved the highest level of education. Educational outcomes remained similar for those with pDCD, regardless of childhood attention deficit.

CONCLUSIONS

pDCD during childhood may have a lasting impact on educational outcomes, particularly among women. Raising awareness of DCD among parents, health and educational professionals is vital for early identification and the provision of appropriate support and interventions in schools, mitigating the potential negative consequences associated with DCD and promoting positive educational outcomes.

Perspective: Acknowledging complexity to advance the understanding of developmental coordination disorder

Developmental Coordination Disorder (DCD) is a heterogeneous neurodevelopmental disorder known for primary symptoms of motor learning and execution difficulties. Recent research has consistently suggested DCD symptoms span broadly beyond motor difficulties, yet a majority of research and practice approaches the investigation, diagnosis, and treatment of DCD with a reductionist framework. Therefore, this paper suggests the paradigm of complexity theory as a means for better conceptualization, assessment, and treatment of DCD. First, the perspective of complexity theory and its relevance to DCD is described. Then, examples from recent research which attempt to acknowledge and capture the complex nature of DCD are highlighted. Finally, suggestions for considering and measuring complexity of DCD in future research and practice are provided. Overall, the perspective of complexity can propel the research forward and improve the understanding of DCD relevant to assessment and treatment. The complexity paradigm is highly relevant to describing the evolving and multidimensional picture of DCD, understanding heterogeneous symptom profiles, making connections to interconnected secondary symptoms, and beyond.

How are you getting by? Coping in developmental coordination disorder versus attention-deficit/hyperactivity disorder

Objective

Developmental Coordination Disorder (DCD) and Attention-Deficit/Hyperactivity Disorder (ADHD) persist into adulthood; however, little research exists to describe how adults with DCD and/or ADHD cope with their symptoms. Therefore, the purpose of this study was to investigate coping mechanisms reported by adults with DCD, ADHD, or both conditions. We expected there would be strategies specific to each condition and a broader scope of mechanisms reported by those with co-occurring DCD+ADHD.

Method

N = 161 participants completed the online survey, including n = 31 with DCD only, n = 116 with ADHD only, and n = 14 with DCD+ADHD.

Results

Most participants reported adaptive strategies. Of these, behavioral adaptations were most relevant to ADHD, while environmental modifications were common in DCD. Cognitive reframing and social support were similarly relevant to those with DCD and DCD+ADHD. Coping strategy categories were most uniform for the DCD+ADHD group.

Conclusions

Coping profiles highlight several noteworthy differences between DCD and ADHD which may be relevant for treatment.

Developmental Coordination Disorder (DCD): Relevance for Clinical Psychologists in Europe

Background

Developmental Coordination Disorder (DCD) is a common neurodevelopmental disorder primarily characterized by fine and gross motor coordination difficulties. Yet, many aspects remain unclear regarding the clinical presentation of secondary symptoms and their implications for Clinical Psychology. Therefore, the purpose of this review is to provide an update about the current understanding of DCD for clinical psychologists and psychotherapists across Europe, particularly based on new insights stemming from the last decade of research.

Method

We provide a narrative review of articles published in the last decade on the topic of DCD, and relevant aspects to clinical psychologist, including lesser known aspects of DCD (e.g., executive functions, psychological consequences, and adult DCD).

Results

DCD is a highly prevalent, disruptive, and complex disorder, which should be investigated further in many areas (e.g., co-occurrence to ADHD). Existing evidence points toward a key role of executive functioning difficulties at all ages. Most patients report secondary psychological problems, but little headway has been made in examining the effectiveness of psychotherapy for DCD.

Conclusions

Insights and remaining research gaps are discussed. It is critical for psychologists and clinical researchers to raise awareness for DCD, take note of the growing literature, and foster continued interdisciplinary approaches to research and treatment of DCD.