ADHD: volumetry, motor, and oculomotor functions

Oculomotor deficits in attention deficit hyperactivity disorder: a systematic review and meta-analysis

There is equivocal evidence on the presence of oculomotor deficits among children with attention deficit hyperactivity disorder (ADHD), which can be an additional challenge in this population, especially with reading-related tasks. This study aimed to review the deficits in the oculomotor parameters among children with ADHD compared with age-matched controls. The review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. A search of original research articles on various databases was done using key terms, such as "oculomotor deficit," "attention deficit hyperactivity disorder," or related terms. We included case-control studies and excluded studies in which children received medications during the test. Twelve original research studies were considered for this review. Ten studies reported data on various types of saccades, two studies reported data on fixation, and one study reported data on pursuit. Among various oculomotor deficits, the forest-plot analysis of an antisaccade task showed that children with ADHD made more direction errors compared to controls. Although independent studies report that ADHD children have poorer performance compared to control populations during oculomotor tasks, there is a lack of evidence to draw a strong conclusion. Children with ADHD are less precise in performing eye movements and need more time to complete the oculomotor tasks than those without ADHD. The overall results provide minimal evidence regarding the presence of various oculomotor deficits in ADHD.

Development of coordination and muscular fitness in children and adolescents with parent-reported ADHD in the German longitudinal MoMo Study

This study examined the development of muscular fitness and coordination in children and adolescents with and without attention deficit hyperactivity disorder (ADHD) over a period of 11 years. Data was collected in three measurement waves as part of the longitudinal, representative Motorik-Modul (MoMo) study in Germany (2003-2006, 2009-2012, 2014-2017). The overall sample comprised 2988 participants (253 with ADHD, 65% males; 2735 non-ADHD, 47% males; mean age 9 years). Structural equation modeling was conducted, and the estimated models had a good fit. No differences in muscular fitness were observed between participants with and without ADHD. Participants with ADHD had a lower coordinative performance at first measurement than those without ADHD. The difference in coordinative performance persisted throughout the study period.

Is There a Functional Relation Between Set Shifting and Hyperactivity in Children with Attention-Deficit/Hyperactivity Disorder (ADHD)?

OBJECTIVE

Replicated evidence indicates that children with attention-deficit/hyperactivity disorder (ADHD) show disproportionate increases in hyperactivity/physical movement when their underdeveloped executive functions are taxed. However, our understanding of hyperactivity's relation with set shifting is limited, which is surprising given set shifting's importance as the third core executive function alongside working memory and inhibition. The aim of this study was to experimentally examine the effect of imposing set shifting and inhibition demands on objectively measured activity level in children with and without ADHD.

METHOD

The current study used a validated experimental manipulation to differentially evoke set shifting, inhibition, and general cognitive demands in a carefully phenotyped sample of children aged 8-13 years with ADHD (n = 43) and without ADHD (n = 34). Activity level was sampled during each task using multiple, high-precision actigraphs; total hyperactivity scores (THS) were calculated.

RESULTS

Results of the 2 × 5 Bayesian ANOVA for hyperactivity revealed strong support for a main effect of task (BF10 = 1.79 × 1018, p < .001, ω2 = .20), such that children upregulated their physical movement in response to general cognitive demands and set shifting demands specifically, but not in response to increased inhibition demands. Importantly, however, this manipulation did not disproportionally increase hyperactivity in ADHD as demonstrated by significant evidence against the task × group interaction (BF01 = 18.21, p = .48, ω2 = .002).

CONCLUSIONS

Inhibition demands do not cause children to upregulate their physical activity. Set shifting produces reliable increases in children's physical movement/hyperactivity over and above the effects of general cognitive demands but cannot specifically explain hyperactivity in children with ADHD.

Effect of a visual tracking intervention on attention and behavior of children with Attention Deficit Hyperactivity Disorder

Attention deficit hyperactivity disorder is characterized by several cognitive and behavioral problems such as inattention and impulsivity, abnormal control of eye movements and relocation, visual fixation and visuospatial perception. There is a link between core motor functions such as oculomotor function and cognition to the extent that the oculomotor system acts as a mediator between the motor and cognitive functions. Therefore, the effects of eye-tracking intervention were investigated on attention in these children. Thirty - nine boys with ADHD, 6 to 10 years of age were recruited and randomized to receive current occupational therapy (control group), or occupational therapy accompanied with eye-tracking exercises (experimental group). They were evaluated using the Conner's Parent Rating Scale, the Continuous Performance Task-2, and the Test of Visual-Motor Skills-Revised before and after the intervention. Significant improvements in the mean scores of cognitive problems (F=9/22), coping behavior (F=6.03) and hyperactivity (F=9.77) were detected in the posttest between the two groups (p<0.05). Furthermore, in the Continuous Performance Test scores, detectability (F=5.68), omission errors (F=17.89), commission errors (F=19.45), reaction time (F=8.95), variability (F=7.07), and preservation (F=6.33) showed significant differences between control and experimental groups (p<0.01). It appears that eye-tracking interventions designed based on the isolation of neck and eye movement might have an important role in improving cognitive function and coping behaviors in these children. It seems that these exercises could increase eye movement control; improve cognitive function and response inhibition.

Exercise Interventions in Children and Adolescents With ADHD: A Systematic Review

OBJECTIVE

Exercise has attracted attention as a potential helpful intervention in children with ADHD. Effects are emphasized on cognition, social-emotional, and motor development.

METHOD

A systematic literature search was conducted using the electronic databases Web of Science, PubMed, Scopus, and ERIC to analyze the efficacy of different types of exercise interventions in children and adolescents with ADHD. Seven studies examining the acute and 14 studies examining the long-term effects were included.

RESULTS

The largest effects were reported for mixed exercise programs on ADHD symptomatology and fine motor precision. However, because of the large differences in the study designs, the comparability is limited.

CONCLUSION

At this time, no evidence-based recommendation can be formulated regarding frequency, intensity, or duration of exercise. Nevertheless, some first trends regarding the effects of certain types of exercise can be identified. When focusing on long-term health benefits in children and adolescents with ADHD, qualitative exercise characteristics might play an important role.

Motor dysfunction as research domain across bipolar, obsessive-compulsive and neurodevelopmental disorders

Although genuine motor abnormalities (GMA) are frequently found in schizophrenia, they are also considered as an intrinsic feature of bipolar, obsessive-compulsive, and neurodevelopmental disorders with early onset such as autism, ADHD, and Tourette syndrome. Such transnosological observations strongly suggest a common neural pathophysiology. This systematic review highlights the evidence on GMA and their neuroanatomical substrates in bipolar, obsessive-compulsive, and neurodevelopmental disorders. The data lends support for a common pattern contributing to GMA expression in these diseases that seems to be related to cerebello-thalamo-cortical, fronto-parietal, and cortico-subcortical motor circuit dysfunction. The identified studies provide first evidence for a motor network dysfunction as a correlate of early neurodevelopmental deviance prior to clinical symptom expression. There are also first hints for a developmental risk factor model of these mental disorders. An in-depth analysis of motor networks and related patho-(physiological) mechanisms will not only help promoting Research Domain Criteria (RDoC) Motor System construct, but also facilitate the development of novel psychopharmacological models, as well as the identification of neurobiologically plausible target sites for non-invasive brain stimulation.

Performance lapses in children with attention-deficit/hyperactivity disorder contribute to poor reading fluency

Children with Attention-Deficit/Hyperactivity Disorder (ADHD) demonstrate increased response variability compared with controls, which is thought to be associated with deficits in attention regulation and response control that subsequently affect performance of more cognitively demanding tasks, such as reading. The present study examined response variability during a computerized simple reaction time (RT) task in 67 children. Ex-Gaussian analyses separated the response time distribution into normal (mu and sigma) and exponential (tau) components; the association of each with reading fluency was examined. Children with ADHD had significantly slower, more variable, and more skewed RTs compared with controls. After controlling for ADHD symptom severity, tau (but not mu or mean RT) was significantly associated with reduced reading fluency, but not with single word reading accuracy. These data support the growing evidence that RT variability, but not simply slower mean response speed, is the characteristic of youth with ADHD and that longer response time latencies (tau) may be implicated in the poorer academic performance associated with ADHD.