The influence of motor function on processing speed in preterm and term-born children

Reduced hippocampal subfield volumes and memory performance in preterm children with and without germinal matrix-intraventricular hemorrhage

Preterm newborns with germinal matrix-intraventricular hemorrhage (GM-IVH) are at a higher risk of evidencing neurodevelopmental alterations. Present study aimed to explore the long-term effects that GM-IVH have on hippocampal subfields, and their correlates with memory. The sample consisted of 58 participants, including 36 preterm-born (16 with GM-IVH and 20 without neonatal brain injury), and 22 full-term children aged between 6 and 15 years old. All participants underwent a cognitive assessment and magnetic resonance imaging study. GM-IVH children evidenced lower scores in Full Intelligence Quotient and memory measures compared to their low-risk preterm and full-term peers. High-risk preterm children with GM-IVH evidenced significantly lower total hippocampal volumes bilaterally and hippocampal subfield volumes compared to both low-risk preterm and full-term groups. Finally, significant positive correlations between memory and hippocampal subfield volumes were only found in preterm participants together; memory and the right CA-field correlation remained significant after Bonferroni correction was applied (p = .002). In conclusion, memory alterations and both global and regional volumetric reductions in the hippocampus were found to be specifically related to a preterm sample with GM-IVH. Nevertheless, results also suggest that prematurity per se has a long-lasting impact on the association between the right CA-field volume and memory during childhood.

Effortful control and attention as predictors of cognition in children born preterm

BACKGROUND

Preterm childbirth increases the risk of developmental problems. The aim of the present study was to examine the effects of temperament and attention on the cognition of school-age children who were born preterm, controlling for socioeconomic variables.

MATERIAL AND METHODS

The sample was composed of 50 six-year-old children who were born preterm with very low birth weight. The children were evaluated using the Wechsler Intelligence Scale for Children (WISC-III) and the Cancellation Attention Test. The mothers were interviewed using the Children's Behavior Questionnaire (CBQ). Statistical multiple linear regression analyses were performed.

RESULTS

70% of the children presented average or above-average full intellectual quotient (IQ). In the attention total score, 74% of the children were also within the average range or above. High verbal IQ associated with high maternal schooling explained 73% variability of the full IQ. High attention and maternal schooling, associated with children's temperament with more effortful control, explained 35% variability of the verbal IQ. High attention, associated with high maternal schooling and socioeconomic level, explained 37% variability of the performance IQ. The neonatal clinical variables (gestational age, birth weight, 5th-minute Apgar, and length of stay in neonatal intensive care unit (NICU) and hospital) were not predictors of cognitive outcomes.

CONCLUSION

The majority of the children who were born preterm presented average or above-average cognitive and attentional performances at school age, demonstrating potential resources for learning. Taken together, attention and temperament, associated with maternal schooling and socioeconomic status, were predictors of cognitive outcomes of children born preterm at school age.

Motor Abilities in Adolescents Born Preterm Are Associated With Microstructure of the Corpus Callosum

Background: Preterm birth is associated with increased risk of neuromotor impairment. Rates of major neuromotor impairment (cerebral palsy) have decreased; however, in a large proportion of those who do not develop cerebral palsy impaired neuromotor function is observed and this often has implications for everyday life. The aim of this study was to investigate motor performance in preterm born adolescents without cerebral palsy, and to examine associations with alterations of motor system pathway structure. Design/Methods: Thirty-two adolescents (12 males) without cerebral palsy, born before 33 weeks of gestation (mean 27.4 weeks, SD 2.4; birth weight mean 1,084.5 g; SD 387.2), treated at a single tertiary unit, were assessed (median age 16 years; min 14, max 18). Timed performance and quality of movements were assessed with the Zürich Neuromotor Assessment. Neuroimaging included Diffusion Magnetic Resonance Imaging for tractography of the major motor tracts and measurement of fractional anisotropy as a measure of microstructure of the tracts along the major motor pathways. Separate analyses were conducted for areas with predominantly single and predominantly crossing fiber regions. Results: Motor performance in both tasks assessing timed performance and quality of movements, was poorer than expected in the preterm group in relation to norm population. The strongest significant correlations were seen between performance in tasks assessing movement quality and fractional anisotropy in corpus callosum fibers connecting primary motor, primary somatosensory and premotor areas. In addition, timed motor performance was significantly related to fractional anisotropy in the cortico-spinal and thalamo-cortical to premotor area fibers, and the corpus callosum. Conclusions: Impairments in motor abilities are present in preterm born adolescents without major neuromotor impairment and in the absence of focal brain injury. Altered microstructure of the corpus callosum microstructure appears a crucial factor, in particular for movement quality.

Cognitive outcomes in children and adolescents born very preterm: a meta-analysis

AIM

To estimate the association between very preterm birth (<32wks' gestation) and intelligence, executive functioning, and processing speed throughout childhood and adolescence, and to examine the effects of gestational age, birthweight, and age at assessment.

METHOD

Studies were included if children were born at earlier than 32 weeks' gestation, aged 4 to 17 years, had an age-matched term control group, and if the studies used standardized measures, were published in an English-language peer-reviewed journal, and placed no restrictions on participants based on task performance.

RESULTS

We evaluated 6163 children born very preterm and 5471 term-born controls from 60 studies. Children born very preterm scored 0.82 SDs (95% confidence interval [CI] 0.74-0.90; p<0.001) lower on intelligence tests, 0.51 SDs (95% CI 0.44-0.58; p<0.001) lower on measures of executive functioning, and 0.49 SDs (95% CI 0.39-0.60; p<0.001) lower on measures of processing speed than term-born controls. Gestational age and birthweight were associated with study effect size in intelligence and executive functioning of younger children only. Age at assessment was not associated with study effect size.

INTERPRETATION

Children born very preterm have medium to large deficits in these cognitive domains.

WHAT THIS PAPER ADDS

This meta-analysis is centred on very preterm birth and three cognitive domains. The three critical cognitive domains are intelligence, executive functioning, and processing speed.

Compromised Motor Dexterity Confounds Processing Speed Task Outcomes in Stroke Patients

Most conventional measures of information processing speed require motor responses to facilitate performance. However, although not often addressed clinically, motor impairment, whether due to age or acquired brain injury, would be expected to confound the outcome measure of such tasks. The current study recruited 29 patients (20 stroke and 9 transient ischemic attack) with documented reduction in dexterity of the dominant hand, and 29 controls, to investigate the extent to which 3 commonly used processing speed measures with varying motor demands (a Visuo-Motor Reaction Time task, and the Wechsler Adult Intelligence Scale-IV Symbol Search and Coding subtests) may be measuring motor-related speed more so than cognitive speed. Analyses include correlations between indices of cognitive and motor speed obtained from two other tasks (Inspection Time and Pegboard task, respectively) with the three speed measures, followed by hierarchical regressions to determine the relative contribution of cognitive and motor speed indices toward task performance. Results revealed that speed outcomes on tasks with relatively high motor demands, such as Coding, were largely reflecting motor speed in individuals with reduced dominant hand dexterity. Thus, findings indicate the importance of employing measures with minimal motor requirements, especially when the assessment of speed is aimed at understanding cognitive rather than physical function.

Prevalence of sleep disorders and their relationship with core symptoms of inattention and hyperactivity in children with attention-deficit/hyperactivity disorder

OBJECTIVES

To determine the prevalence of sleep disorders in children with attention-deficit/hyperactivity disorder (ADHD) and in a control population. To examine the relationship between sleep disorders and symptoms of inattention, hyperactivity/impulsiveness and executive dysfunction.

MATERIALS AND METHODS

We studied 126 children with ADHD and 1036 control children aged between 5 and 18 years old. Caregivers completed the Pediatric Sleep Questionnaire and the ADHD Rating Scale (ADHD-RS). Children with ADHD were subsequently assessed for executive function with the Conner's Continuous Performance Test (CPT) or with AULA Nesplora.

RESULTS

Children with ADHD slept less at night and were more likely to display sleep-related rhythmic movements. Children in the ADHD group who were under 12 years old and who had total ADHD-RS scores over the 90th percentile had more difficulty falling asleep than other children; there was also a relationship between total ADHD-RS scores over the 90th percentile and certain parasomnias in the control population. There was a correlation between shorter duration of night-time sleep and omission errors in children who were 12 or older and who were under pharmacological treatment for ADHD. Bedtime resistance and difficulty falling sleep were more frequent in children with ADHD whose symptoms were not treated pharmacologically, than in children receiving treatment.

INTERPRETATION

Symptoms of inattention and hyperactivity are correlated with impaired sleep duration and quality; specifically, there is an association between ADHD symptoms and problems falling asleep and parasomnias, however, the current study does not address the nature and direction of causality. Children with ADHD and receiving methylphenidate had fewer sleep disorders, suggesting that, at least in some children, stimulant treatment is associated with improvement of some aspects of sleep. Shorter sleep duration in adolescents under pharmacological treatment for ADHD tended to result in more errors of omission, suggesting that it is important to promote good sleep habits in this population.