Slower reaction times and impaired learning in young adults with birth weight <1500 g

Preterm birth accelerates the maturation of spontaneous and resting activity in the visual cortex

Prematurity is among the leading risks for poor neurocognitive outcomes. The brains of preterm infants show alterations in structure and electrical activity, but the underlying circuit mechanisms are unclear. To address this, we performed a cross-species study of the electrophysiological activity in the visual cortices of prematurely born infants and mice. Using electroencephalography (EEG) in a sample of healthy preterm (N = 29) and term (N = 28) infants, we found that the maturation of the aperiodic EEG component was accelerated in the preterm cohort, with a significantly flatter 1/f slope when compared to the term infants. The flatter slope was a result of decreased spectral power in the theta and alpha bands and was correlated with the degree of prematurity. To determine the circuit and cellular changes that potentially mediate the changes in 1/f slope after preterm birth, we used in vivo electrophysiology in preterm mice and found that, similar to infants, preterm birth results in a flattened 1/f slope. We analyzed neuronal activity in the visual cortex of preterm (N = 6) and term (N = 9) mice and found suppressed spontaneous firing of neurons. Using immunohistochemistry, we further found an accelerated maturation of inhibitory circuits. In both preterm mice and infants, the functional maturation of the cortex was accelerated, underscoring birth as a critical checkpoint in cortical maturation. Our study points to a potential mechanism of preterm birth-related changes in resting neural activity, highlighting the utility of a cross-species approach in studying the neural circuit mechanisms of preterm birth-related neurodevelopmental conditions.

Preterm birth accelerates the maturation of spontaneous and resting activity in the visual cortex

Prematurity is among the leading risks for poor neurocognitive outcomes. The brains of preterm infants show alterations in structure and electrical activity, but the underlying circuit mechanisms are unclear. To address this, we performed a cross-species study of the electrophysiological activity in the visual cortices of prematurely born infants and mice. Using electroencephalography (EEG) in a sample of healthy preterm (N=29) and term (N=28) infants, we found that the maturation of the aperiodic EEG component was accelerated in the preterm cohort, with a significantly flatter 1/f slope when compared to the term infants. The flatter slope was a result of decreased spectral power in the theta and alpha bands and was correlated with the degree of prematurity. To determine the circuit and cellular changes that potentially mediate the changes in 1/f slope after preterm birth, we used in vivo electrophysiology in preterm mice and found that, similar to infants, preterm birth results in a flattened 1/f slope. We analyzed neuronal activity in the visual cortex of preterm mice (N=6 preterm and 9 term mice) and found suppressed spontaneous firing of neurons. Using immunohistochemistry, we further found an accelerated maturation of inhibitory circuits. In both preterm mice and infants, the functional maturation of the cortex was accelerated, underscoring birth as a critical checkpoint in cortical maturation. Our study points to a potential mechanism of preterm birth-related changes in resting neural activity, highlighting the utility of a cross-species approach in studying the neural circuit mechanisms of preterm birth-related neurodevelopmental conditions.

Outcomes into adulthood of infants born extremely preterm

As survival of infants born extremely preterm increases, more are now reaching adulthood. It is well documented that survivors born extremely preterm experience more developmental delay and disability in multiple domains compared with term-born controls in early childhood and school age. However, with increasing age, health problems involving physical and mental health become more evident. Despite these challenges, it is reassuring that self-reported quality of life remains good. Future directions of research include development of age-appropriate interventions to optimise health and development of individuals born extremely preterm beyond school age.

Phasic and tonic alertness in preterm 5-year-old healthy children

Preterm delivery may interrupt the intrauterine brain development and implies a risk factor for the developing brain. In the long term, most frequently particular forms of attention deficits are described which refer to the basic aspects of attention i.e., arousal or tonic alertness. As this reflects top-down processes, the current study focuses on bottom-up processed phasic alertness in preschool aged preterm children. Additionally, we made a division of response times into decision and movement time to quantify more exactly the contribution of cognitive and motor performance to reaction times. We investigated basic aspects of attention functioning and contrasted phasic and tonic alertness in 31 low-risk healthy preterm (28-36 weeks of gestation) and 22 term children of five to 6 years of age by using a self-designed computerized test. Preterm children exhibited delayed decision and reaction time in the tonic non-cued alertness condition but not in the phasic cued alertness condition compared to term children. Current results suggest that preterm birth, even when clinically relevant symptoms are absent, may have long-term consequences on basic aspects of attention functioning. Results further suggest that preterm children may profit from auditory cues to overcome these deviations, which yield evidence for a clear distinction between impaired top-down and intact bottom-up controlled processes. These findings might provide a promising groundwork for the development of therapeutical interventions and prevention strategies, whose use and impact to support preterm children should be addressed in further investigations.

Reaction times, learning, and executive functioning in adults born preterm

BACKGROUND

This study examines cognitive functioning in adults born across the range of prematurity with appropriate or small for gestational age (SGA) birth weight compared with full-term controls.

METHODS

ESTER Preterm Birth Study participants without severe disabilities, comprising 133 early preterm (<34 weeks, 17% SGA), 241 late preterm (34 + 0-36 + 6 weeks, 13% SGA), and 348 full-term subjects, performed the Cogstate® test at a mean age of 23.3 (SD = 1.2) years. Subtests measured paired associate learning, psychomotor function, executive function, spatial memory efficiency, visual memory, attention, working memory, visual learning, and emotional cognition. Data were analyzed with linear regression, full models adjusted for prenatal and postnatal factors and socioeconomic position.

RESULTS

Early preterm, late preterm, and full-term participants showed similar abilities in almost all subtests. Early preterm participants had 0.6 fewer moves/10 s (95% CI: -1.0; -0.2, full model) and late preterm and SGA participants had 1.3 fewer moves/10 s (95% CI: -2.1; -0.4) than full-term controls in the Groton Maze Learning Test, indicating weaker spatial memory efficiency.

CONCLUSIONS

Adults born across the range of prematurity on average lack major defects in cognitive abilities. Cognitive problems may persist to adulthood only among those born the smallest: very preterm or preterm and SGA.

IMPACT

Although preterm birth is a risk for the developing brain, adults born preterm as a group showed similar cognitive performance to their full-term peers. Children born preterm across gestational ages show defects in cognitive domains. With a supportive environment, many of them have the potential to catch up with those born at term. The unfavorable effect of late preterm birth on cognitive functions in childhood may not persist to adulthood; in this study, adults born late preterm showed similar cognitive functioning to adults born full-term. The deficits in cognitive function in adults born preterm detected by earlier studies mainly concern those born the smallest, i.e., very preterm or preterm and small for gestational age.

Poorer outcomes of all low birth weight groups at age 10: Missouri statewide case-control study

BACKGROUND

In 1989-1991, a population-based cohort of every Missouri birth weighing < 1500 g was identified over a 16-month period. Infants born moderately low birth weight (MLBW, 1500-2499 g) and normal birth weight (NBW, ≥ 2500 g), were matched to < 1500 g infants by delivery date, race, maternal age, and residence.

AIMS

To compare outcomes of extremely low birth weight (ELBW, < 1000 g), very low birth weight (VLBW, 1000-1499 g), and MLBW, to NBW infants at age 10.

STUDY DESIGN

A population-based cohort and matched case-control study OUTCOME MEASURES: A Child Health and Development Questionnaire developed for this study collected social, medical, educational and special services history. The Conners' Parent Rating Scale-Revised was also completed by parents/caregivers.

RESULTS

As birth weight declined, the prevalence of adverse outcomes increased. Children in all LBW groups were more likely than NBW children to have problems in speech and language, vision, fine and gross motor tasks, illnesses, attention, school performance, and increased requirements for therapy and accommodation. Repetition of a grade was three times higher for MLBW children and over three times higher for the other LBW groups.

CONCLUSION

In this statewide population-based study, controlling for child's sex, mother's age, race, residence, education, marital status, Medicaid assistance, and smoking or alcohol use during pregnancy, failed to eliminate the strong effect of decreasing birth weight. Problems were most frequent in ELBW, however, VLBW and MLBW also had many significantly greater problems than NBW children. All LBW groups of children experienced greater adverse health and developmental outcomes resulting in significant habilitation and educational challenges.

Executive function relates to surface area of frontal and temporal cortex in very-low-birth-weight late teenagers

BACKGROUND

Being born with very low birth weight (VLBW; birth weight (BW) ≤1500 g) is associated with increased risk of maldevelopment of the immature brain which may affect neurological functioning. Deficits in attention and executive function problems have been reported in VLBW survivors compared with healthy subjects.

AIMS

The aim of this study was to evaluate attention and executive functions and to relate the clinical test results to cortical morphometry findings in VLBW young adults compared with term-born controls.

STUDY DESIGN

Prospective follow-up study of three year cohorts of VLBW and control children from birth to adulthood.

OUTCOME MEASURES

A comprehensive neuropsychological test battery was administered to 55 VLBW subjects born preterm (mean BW: 1217 g) and 81 term-born controls (mean BW: 3707 g) at age 19-20. Cerebral MRI was successfully obtained in 46 VLBW subjects and 61 controls. The FreeSurfer software package was applied for the cortical analyses based on T1-weighted MRI images.

RESULTS

The VLBW group obtained inferior scores on 15 of the 29 neuropsychological measures assessing attention and executive function and on both the attention and executive function domain scores. We found positive correlations between the executive function domain score and cortical surface area, especially in the antero-medial frontal and the temporal lobes of the brain in the VLBW group.

CONCLUSION

Young adults born with VLBW show deficits in attention and executive function compared with controls. The executive problems were related to smaller cortical surface area in brain regions known to be involved in higher order cognitive functioning.

Preterm Cognitive Function Into Adulthood

BACKGROUND

Very preterm (VP; gestational age <32 weeks) and very low birth weight (VLBW; <1500 g) births are related to impaired cognitive function across the life span. It is not known how stable cognitive functions are from childhood to adulthood for VP/VLBW compared with term-born individuals and how early adult cognitive function can be predicted.

METHODS

The Bavarian Longitudinal Study is a prospective geographically defined cohort study that followed 260 VP/VLBW and 229 term-born individuals from birth to adulthood. Data on cognitive function were assessed with developmental and IQ tests at 5 and 20 months and at 4, 6, 8, and 26 years of age.

RESULTS

Across all assessments, VP/VLBW individuals had significantly lower IQ scores than term-born controls, even when individuals with severe cognitive impairment (n = 69) were excluded. IQ scores were found to be more stable over time for VP/VLBW than term-born individuals, yet differences in stability disappeared when individuals with cognitive impairment were excluded. Adult IQ could be predicted with fair certainty (r > 0.50) from age 20 months onward for the whole VP/VLBW sample (n = 260) and from 6 years onward for term-born individuals (n = 229).

CONCLUSIONS

VP/VLBW individuals more often suffer from cognitive problems across childhood into adulthood and these problems are relatively stable from early childhood onward. VP/VLBW children's risk for cognitive problems can be reliably diagnosed at the age of 20 months. These findings provide strong support for the timing of cognitive follow-up at age 2 years to plan special support services for children with cognitive problems.

Neuro-cognitive performance of very preterm or very low birth weight adults at 26 years

BACKGROUND

Children born very preterm (VP <32 weeks gestation) and/or with very low birth weight (VBLW <1500 g; subsequently VP/VLBW) have been previously reported to have more cognitive impairment and specific executive functioning problems than term children; however, it remains unclear whether these problems persist into adulthood. This study aimed to examine general intelligence (IQ) and executive functioning (EF) of adults born VP/VLBW in comparison to term controls. Additionally, the effects of smallness for gestational age (SGA) and family socioeconomic status (SES) at birth were investigated.

METHODS

The Bavarian Longitudinal Study is a geographically defined prospective cohort study of neonatal at-risk children born in 1985/86 in Southern Germany. A total of 217 VP/VLBW and 197 controls completed the battery of IQ and EF tests at 26 years of age.

RESULTS

VP/VLBW adults scored significantly lower than controls in IQ and EF. There was a 1.16 standard deviation (SD) unit difference between the VP/VLBW and controls in Full-Scale IQ. VP/VLBW adults were found to have general and multiple cognitive problems rather than specific deficits in EF. SGA was not a significant predictor of cognitive impairment. Family SES had a significant impact on general intelligence in both VP/VLBW and term controls. The SES effects amounted to 1.13 SD units between individuals born into high versus low SES.

CONCLUSIONS

No narrowing of cognitive deficits between VP/VLBW and term control adults to previous childhood assessments at 6 years of age was found. VP/VLBW adults do not outgrow their cognitive problems despite many receiving special educational support in childhood. Low family SES at birth has similar additive adverse effects on cognitive performance in VP/VLBW and term offspring.

Executive function in adolescents born <1000 g or <28 weeks: a prospective cohort study

BACKGROUND AND OBJECTIVES

Extremely preterm (EP; <28 weeks) birth and extremely low birth weight (ELBW; <1000 g) are risk factors for poor cognitive outcomes, including in executive function (EF; higher-order cognitive skills necessary for goal-directed, adaptive functioning and important for academic and behavioral-emotional outcomes). We aimed to (1) extend the limited data on EF in EP/ELBW survivors in adolescence compared with normal birth weight controls, and (2) determine changes in EF between ages 8 and 17 years in both groups.

METHODS

Two hundred twenty-eight EP/ELBW and 166 control adolescents (mean age, 17 years) from a prospective geographical cohort were assessed with multiple EF tasks, and parent- and self-ratings of behavioral EF. The Rey Complex Figure and Behavior Rating Inventory of Executive Function parent report were also administered at age 8 years, enabling examination of change in scores between childhood and adolescence.

RESULTS

EP/ELBW adolescents performed more poorly than controls in verbal processing speed, attentional control, cognitive flexibility, and goal-setting (effect sizes, -0.7 to -0.2 SD), but not psychomotor reaction time. Group differences were of similar magnitude across tasks. From childhood to late adolescence, EP/ELBW children improved their accuracy of the Rey Complex Figure copy more than controls. According to parents, executive behaviors were largely stable over time in both groups.

CONCLUSIONS

Adolescents born EP/ELBW have poorer EF skills across multiple domains than controls. From childhood to late adolescence, different aspects of EF improved, but others did not, underscoring the need for multidomain, longitudinal assessments in this high-risk population.

Infant growth after preterm birth and neurocognitive abilities in young adulthood

OBJECTIVES

To examine whether faster growth from birth to term (40 postmenstrual weeks) and during the first year thereafter was associated with better neurocognitive abilities in adults born preterm with very low birth weight (VLBW; <1500 g).

STUDY DESIGN

Weight, length, and head circumference data of 103 VLBW participants of the Helsinki Study of Very Low Birth Weight Adults were collected from records. Measures at term and at 12 months of corrected age were interpolated. The participants underwent tests of general neurocognitive ability, executive functioning, attention, and visual memory at mean age of 25.0 years.

RESULTS

Faster growth from birth to term was associated with better general neurocognitive abilities, executive functioning, and visual memory in young adulthood. Effect sizes in SD units ranged from 0.23-0.43 per each SD faster growth in weight, length, or head circumference (95% CI 0.003-0.64; P values <.05). After controlling for neonatal complications, faster growth in head circumference remained more clearly associated with neurocognitive abilities than weight or length did. Growth during the first year after term was not consistently associated with neurocognitive abilities.

CONCLUSIONS

Within a VLBW group with high variability in early growth, faster growth from birth to term is associated with better neurocognitive abilities in young adulthood. Neurocognitive outcomes were predicted, in particular, by early postnatal head growth.

Working memory in preterm-born adults: load-dependent compensatory activity of the posterior default mode network

Premature birth is associated with an increased risk of cognitive performance deficits that are dependent on working memory (WM) load in childhood. Less clear is whether preterm-born adults show similar WM impairments, or develop compensatory brain mechanisms that help to overcome prematurity-related functional deficits, for example, by a workload-dependent over-recruitment of WM-typical areas, and/or engagement of alternative brain networks. In this functional magnetic resonance imaging study, 73 adults born very preterm and/or with very low birth weight (VP/VLBW) and 73 term-born controls (CON, mean age: 26.5 years) performed a verbal N-Back paradigm with varying workload (0-back, 1-back, 2-back). Generally, both groups showed similar performance accuracy and task-typical patterns of brain activations (especially in fronto-cingulo-parietal, thalamic, and cerebellar areas) and deactivations (especially in mesial frontal and parietal aspects of the default mode network [DMN]). However, VP/VLBW adults showed significantly stronger deactivations (P < 0.05, cluster-level corrected) than CON in posterior DMN regions, including right ventral precuneus, and right parahippocampal areas (with adjacent cerebellar areas), which were specific for the most demanding 2-back condition. Consistent with a workload-dependent effect, VP/VLBW adults with stronger deactivations (1-back > 2-back) in the parahippocampal/cerebellar cluster also presented a greater slowing of response latencies with increasing WM load (2-back > 1-back), indicative of higher effort. In conclusion, VP/VLBW adults recruited similar anatomical networks as controls during N-back performance, but showed an enhanced suppression of posterior DMN regions during higher workload, which may reflect a temporary suppression of stimulus-independent thoughts that helps to maintain adequate task performance with increasing attentional demands.

Maternal hypertensive pregnancy disorders and cognitive functioning of the offspring: a systematic review

Hypertensive pregnancy disorders may affect the fetal developmental milieu and thus hint at mechanisms that link prenatal conditions with later developmental outcomes of the offspring. Here, we systematically review studies that have tested whether maternal pre-eclampsia, gestational hypertension, and hypertensive pregnancy disorders as a single diagnostic entity are associated with cognitive functioning of the offspring. Twenty-six studies were eligible for this review. Of them, 19 provided detailed methodological information deemed necessary to be included for a more detailed review. An overall conclusion is that, in the general population, maternal hypertensive disorders may be associated with lower cognitive ability of the offspring. Studies that extend to adulthood show the most consistent pattern of findings. It is possible that the associations arise during the lifetime or that the findings reflect improvements in management of these disorders. Evidence is, however, insufficient to conclude whether these associations are dissimilar in the offspring exposed to maternal pre-eclampsia and gestational hypertension, due to the varied criteria used across the different studies to distinguish between these conditions. The existing studies also vary in the definition of control groups, and very few have taken into account important confounding factors, including maternal pre-pregnancy obesity and lifestyle behaviors. Given the mixed pattern of findings and limitations related to internal and external validity, further studies are clearly warranted to clarify the associations.

Hyper-responsiveness to acute stress, emotional problems and poorer memory in former preterm children

The prevalence of preterm birth (PTB) is high worldwide, especially in developing countries like Brazil. PTB is marked by a stressful environment in intra- as well as extrauterine life, which can affect neurodevelopment and hormonal and physiological systems and lead to long-term negative outcomes. Nevertheless, little is known about PTB and related outcomes later on in childhood. Thus, the goals of the current study were threefold: (1) comparing cortisol and alpha-amylase (sAA) profiles, including cortisol awakening response (CAR), between preterm and full-term children; (2) evaluating whether preterm children are more responsive to acute stress and (3) assessing their memory skills and emotional and behavioral profiles. Basal cortisol and sAA profiles, including CAR of 30 preterm children, aged 6 to 10 years, were evaluated. Further, we assessed memory functions using the Wide Range Assessment of Memory and Learning, and we screened behavior/emotion using the Strengths and Difficulties Questionnaire. The results of preterm children were compared to an age- and sex-matched control group. One week later, participants were exposed to a standardized laboratory stressor [Trier Social Stress Test for Children (TSST-C)], in which cortisol and sAA were measured at baseline, 1, 10 and 25 min after stressor exposure. Preterm children had higher cortisol concentrations at awakening, a flattened CAR and an exaggerated response to TSST-C compared to full-term children. These alterations were more pronounced in girls. In addition, preterm children were characterized by more emotional problems and poorer memory performance. Our findings illustrate the long-lasting and in part sex-dependent effects of PTB on the hypothalamic-pituitary-adrenal (HPA) axis, internalizing behavior and memory. The findings are in line with the idea that early adversity alters the set-point of the HPA axis, thereby creating a more vulnerable phenotype.

Advanced sleep-wake rhythm in adults born prematurely: confirmation by actigraphy-based assessment in the Helsinki Study of Very Low Birth Weight Adults

OBJECTIVE

Previous studies have suggested a propensity towards morningness in teenagers and adults born preterm. We set out to study sleep in a subsample from The Helsinki Study of Very Low Birth Weight Adults cohort, with emphasis on sleep timing, duration, and quality. We compared young adults who were born prematurely at very low birth weight (VLBW; <1500 g) with controls born at term.

METHODS

We measured sleep by actigraphy in young adults aged 21-29 years. A total of 75 individuals (40 VLBW and 35 controls) provided adequate data. Group differences in sleep parameters were analyzed using t-test and linear regression models.

RESULTS

VLBW adults woke up on average 40 min earlier [95% confidence interval (CI), 9-70] and reported 40 min earlier get up time (95% CI, 8-71) than did the controls. The difference remained after adjustment for confounders. We found no group difference in sleep duration or measures of sleep quality.

CONCLUSION

Our findings of earlier rising in the VLBW group are suggestive of an advanced sleep phase in that group. These results reinforce previous suggestions that chronotype may be programmed early during life.

Birth weight and cognitive function in early adulthood: the Australian Aboriginal birth cohort study

It has been suggested that in addition to genetic factors, fetal and post-natal growth influence cognition in early adulthood. However, most studies have been in developed populations, so it is unclear if the same findings would be seen in other, less developed, settings, and have used testing tools not applicable to an Australia Aboriginal population. This study investigated the relationships between cognitive function in early adulthood and birth weight and contemporary height. Simple reaction time (SRT), choice reaction time (CRT) and working memory (WM) were assessed using the CogState battery. A significant association was seen between birth weight and SRT in early adulthood, but not with the other two cognitive measures. Urban dwellers had significantly shorter SRT and CRT than their remote counterparts. Contemporary body mass index and maternal age were associated with CRT. Only fetal growth restriction was associated with WM, with greater WM in those with restricted growth. No associations were seen with contemporary height. These results suggest that fetal growth may be more important than the factors influencing post-natal growth in terms of cognition in early adulthood in this population, but that the associations may be inconsistent between cognitive outcomes. Further research is required to identify whether similar associations are seen in other, similar, populations and to assess why differences in cognitive outcome measures are seen.

Neuropsychological outcomes of children born very preterm

Considerable research has investigated the consequences of being born very preterm (VP; <32 weeks of gestation), especially in relation to cognitive functioning. While numerous cognitive and neuropsychological outcome studies have been published, it is important to consider methodological issues when reviewing this research, as the generalizability of the studies varies greatly. This article describes the nature of cognitive difficulties confronting VP children, both in terms of the frequency and severity of deficits. The breadth of cognitive difficulties reported in this population implies a generalized cognitive impairment; however, the presence of selective or primary cognitive deficits is discussed. It is concluded that whereas mortality and neonatal morbidity rates have decreased significantly in VP infants in recent decades, these children continue to be at significant risk for cognitive impairments and need to be closely monitored throughout childhood.

Preventing academic difficulties in preterm children: a randomised controlled trial of an adaptive working memory training intervention - IMPRINT study

Background

Very preterm children exhibit difficulties in working memory, a key cognitive ability vital to learning information and the development of academic skills. Previous research suggests that an adaptive working memory training intervention (Cogmed) may improve working memory and other cognitive and behavioural domains, although further randomised controlled trials employing long-term outcomes are needed, and with populations at risk for working memory deficits, such as children born preterm.

In a cohort of extremely preterm (<28 weeks’ gestation)/extremely low birthweight (<1000 g) 7-year-olds, we will assess the effectiveness of Cogmed in improving academic functioning 2 years’ post-intervention. Secondary objectives are to assess the effectiveness of Cogmed in improving working memory and attention 2 weeks’, 12 months’ and 24 months’ post-intervention, and to investigate training related neuroplasticity in working memory neural networks 2 weeks’ post-intervention.

Methods/Design

This double-blind, placebo-controlled, randomised controlled trial aims to recruit 126 extremely preterm/extremely low birthweight 7-year-old children. Children attending mainstream school without major intellectual, sensory or physical impairments will be eligible. Participating children will undergo an extensive baseline cognitive assessment before being randomised to either an adaptive or placebo (non-adaptive) version of Cogmed. Cogmed is a computerised working memory training program consisting of 25 sessions completed over a 5 to 7 week period. Each training session takes approximately 35 minutes and will be completed in the child’s home. Structural, diffusion and functional Magnetic Resonance Imaging, which is optional for participants, will be completed prior to and 2 weeks following the training period. Follow-up assessments focusing on academic skills (primary outcome), working memory and attention (secondary outcomes) will be conducted at 2 weeks’, 12 months’ and 24 months’ post-intervention.

Discussion

To our knowledge, this study will be the first randomised controlled trial to (a) assess the effectiveness of Cogmed in school-aged extremely preterm/extremely low birthweight children, while incorporating advanced imaging techniques to investigate neural changes associated with adaptive working memory training, and (b) employ long-term follow-up to assess the potential benefit of improved working memory on academic functioning. If effective, Cogmed would serve as a valuable, available intervention for improving developmental outcomes for this population.

Trial registration

Australian New Zealand Clinical Trials Registry ACTRN12612000124831.

fMRI: blood oxygen level-dependent activation during a working memory-selective attention task in children born extremely preterm

BACKGROUND

Extremely preterm (EPT)/extremely low-birth-weight (ELBW) children attaining school age and adolescence often have problems with executive functions such as working memory and selective attention. Our aim was to investigate a hypothesized difference in blood oxygen level-dependent (BOLD) activation during a selective attention-working memory task in EPT/ELBW children as compared with term-born controls.

METHODS

A regional cohort of 28 EPT/ELBW children and 28 term-born controls underwent functional magnetic resonance imaging (fMRI) scanning at 11 y of age while performing a combined Stroop n-back task. Group differences in BOLD activation were analyzed with Statistical Parametric Mapping 8 analysis software package, and reaction times (RTs) and response accuracy (RA) were compared in a multifactorial ANOVA test.

RESULTS

The BOLD activation pattern in the preterm group involved the same areas (cingulate, prefrontal, and parietal cortexes), but all areas displayed significantly less activation than those in the control group, particularly when the cognitive load was increased. The RA results corresponded with the activation data in that the preterm group had significantly fewer correct responses. No group difference was found regarding RTs.

CONCLUSION

Children born EPT/ELBW displayed reduced working memory and selective attention capacity as compared with term-born controls. These impairments had neuronal correlates with reduced BOLD activation in areas responsible for online stimulus monitoring, working memory, and cognitive control.

Structural and functional brain correlates of behavioral outcomes during adolescence

Several studies have described an association between very preterm birth and behavioral and psychiatric outcomes in childhood and adolescence. The exact mechanisms underlying this association are unknown, but impaired neurodevelopment has been proposed as a possible etiological factor. Existing research suggests a selective vulnerability of brain regions associated with a variety of behavioral and psychiatric outcomes following very preterm birth. This article reviews studies that have directly explored the structural and functional brain correlates of behavioral outcomes in ex-preterm individuals, with an emphasis on attentional problems, overall mental health functioning including internalizing and externalizing scores, and psychosocial adjustment. The focus here is on neuroimaging research conducted during adolescence, a period of life associated with the emergence and early expression of several psychiatric disorders. The neurodevelopmental hypothesis is used as a theoretical framework, according to which early brain lesions interact with the developing brain to increase later vulnerability to psychopathology.

Executive function outcome in preterm adolescents

Preterm birth (PT) and low birthweight (LBW) are risk factors for cognitive, academic, and behavioral difficulties. Executive functioning, which is an umbrella term encompassing higher-order problem-solving and goal-oriented abilities, may help to understand these impairments. This review article examines executive functioning in PT and LBW children, with a specific focus on adolescence and the functional consequences of executive dysfunction in this age group. We have focused on adolescence as it is a critical period for brain, cognitive and social-emotional development, and a period of increased autonomy, independence and reliance on executive functioning. While more longitudinal research is required, there is evidence demonstrating that the PT/LBW population is at increased risk for impairments across all executive domains. Emerging evidence also suggests that executive dysfunction may partly explain poorer academic and social-emotional competence in PT/LBW adolescents. In conclusion, PT/LBW adolescents exhibit poorer executive functioning, and close surveillance is recommended for high-risk individuals.

School-age outcomes of extremely preterm or extremely low birth weight children

OBJECTIVE

Research is required to monitor changes in the nature of neurobehavioral deficits in extremely preterm (EP) or extremely low birth weight (ELBW) survivors. This study examines cognitive, academic, and behavioral outcomes at age 8 years for a regional cohort of EP/ELBW children born in 1997.

METHODS

The EP/ELBW cohort comprised all live births with a gestational age <28 weeks (EP) or birth weight <1000 g (ELBW) born in the state of Victoria, Australia, in 1997. Of 317 live births, 201 (63.4%) survived to 2 years of age.A term/normal birth weight (T/NBW) cohort was recruited comprising 199 infants with birthweights ≥2500 g or gestational age ≥37 weeks [corrected]. Measures of intellectual ability, educational achievement, and behavior were administered at age 8.

RESULTS

Retention was 94% for the EP/ELBW group and 87% for the T/NBW group. The EP/ELBW group performed poorer than the T/NBW group on measures of IQ, educational achievement, and certain behavioral domains, even after adjustment for sociodemographic factors and exclusion of children with neurosensory impairment. The rate of any neurobehavioral impairment was elevated in the EP/ELBW group (71% vs 42%), and one-half of subjects had multiple impairments. The outcomes for those with <750 g birth weight or <26 weeks' gestational age were similar to those with a birth weight of 750 to 999 g or a gestational age of 26 to 27 weeks, respectively.

CONCLUSIONS

Despite ongoing improvements in the management of EP/ELBW infants, the rate of neurobehavioral impairment at school-age remains too high relative to controls.

Maternal hypertensive disorders in pregnancy and self-reported cognitive impairment of the offspring 70 years later: the Helsinki Birth Cohort Study

OBJECTIVE

We tested whether maternal hypertensive disorders during pregnancy predict self-reported cognitive impairment, which is one of the earliest behavioral markers of dementia, of the offspring 70 years later.

STUDY DESIGN

We included 876 participants of the Helsinki Birth Cohort Study 1934-44 who were born after normotensive, preeclamptic, or hypertensive pregnancies that were defined by the use of the mother's blood pressure and urinary protein measurements at maternity clinics and birth hospitals. The participants completed a psychological questionnaire that included questions on cognitive failures and dysexecutive functioning at an average age of 69.3 ± 3.1 (SD) years.

RESULTS

In comparison with the offspring who were born after normotensive pregnancies, the offspring who were born after preeclamptic pregnancies reported more frequent complaints of cognitive failures, distractibility, and false triggering. Further, among women we found maternal hypertension without proteinuria that was associated with more frequent complaints of cognitive failures, forgetfulness, and false triggering.

CONCLUSION

Hypertensive disorders during pregnancy are associated with more frequent subjective complaints of cognitive failures of the offspring in old age.

The Perinatal Adverse events and Special Trends in Cognitive Trajectory (PLASTICITY) - pre-protocol for a prospective longitudinal follow-up cohort study

Prospective follow-up studies on long term effects of pre- and perinatal adverse conditions in adulthood are rare. We will continue to follow the prospective cohort of initially 1196 subjects with predefined at-delivery risk factors out of 22,359 consecutive deliveries during 1971-74 at a single maternity hospital. The risk cohort and 93 controls have been followed up with a comprehensive clinical program at 5, 9, and 16 years of age and by questionnaire at the age of 30 years. Major medical events known to affect the development and growth of the brain, or cognitive functions and personality have been documented. Here we present a pre-protocol for the project, which we will call PLASTICITY, whose aim is to follow consenting subjects and controls into mid-adulthood and beyond, and to explore how the neonatal risk factors modulate neurodevelopmental and neurodegenerative processes such as learning disabilities, ADHD, aging, early onset mild cognitive impairment and even dementia. Our first focus is on the neurological and cognitive outcomes at age 40 years, using detailed neurological, neuropsychological, neuroimaging, genetic, blood chemistry and registry based methods. Results will be expected to offer information on the risk of neurological, psychiatric, metabolic and other medical consequences as well as the need for health and social services at the brink of middle age, when new degenerative phenomena are known to emerge. The evaluation at age 40 years will serve as a baseline for later aging studies. We welcome all comments and suggestions, which we will apply in finalizing details and inviting collaboration.

Self- and parent-rated executive functioning in young adults with very low birth weight

BACKGROUND AND OBJECTIVE

Adults born preterm score lower on performance-based tests of executive functioning (EF) than their term-born peers. These test scores do not necessarily translate to application of these skills in an everyday environment. The objective of the study was to test differences between very low birth weight (VLBW; <1500 g) adults and their term-born peers in self- and parent-rated EF and examine concordance between self- and parent-rated EF and performance-based tests of EF.

METHODS

A longitudinal study of 90 VLBW adults and 93 term-born controls (aged 21-30 years) was performed. The young adults and their parents filled in the Behavioral Rating Inventory of Executive Functioning-Adult Version, and the adults underwent performance-based tests of EF.

RESULTS

VLBW young adults and especially those born appropriate for gestational age reported fewer problems in behavioral regulation and global EF than term-born controls; however, parents of VLBW adults born small for gestational age reported more problems for their children in all EF scales than parents of the controls. Compared with their parents, VLBW young adults reported fewer problems in behavioral regulation. Adults' ratings and their parents' ratings correlated significantly among VLBW and control groups. In the VLBW and VLBW/small-for-gestational-age groups, parent ratings of EF were correlated to performance-based tests, whereas among term-born adults, self-reports correlated.

CONCLUSIONS

These findings reveal that VLBW adults may have learned to compensate in the everyday environment for their EF deficits apparent in performance-based tests. Alternatively, VLBW adults may have positively skewed views of their abilities.

Language and reading skills in school-aged children and adolescents born preterm are associated with white matter properties on diffusion tensor imaging

Children born preterm are at risk for deficits in language and reading. They are also at risk for injury to the white matter of the brain. The goal of this study was to determine whether performance in language and reading skills would be associated with white matter properties in children born preterm and full-term. Children born before 36 weeks gestation (n=23, mean±SD age 12.5±2.0 years, gestational age 28.7±2.5 weeks, birth weight 1184±431 g) and controls born after 37 weeks gestation (n=19, 13.1±2.1 years, 39.3±1.0 weeks, 3178±413 g) underwent a battery of language and reading tests. Diffusion tensor imaging (DTI) scans were processed using tract-based spatial statistics to generate a core white matter skeleton that was anatomically comparable across participants. Fractional anisotropy (FA) was the diffusion property used in analyses. In the full-term group, no regions of the whole FA-skeleton were associated with language and reading. In the preterm group, regions of the FA-skeleton were significantly associated with verbal IQ, linguistic processing speed, syntactic comprehension, and decoding. Combined, the regions formed a composite map of 22 clusters on 15 tracts in both hemispheres and in the ventral and dorsal streams. ROI analyses in the preterm group found that several of these regions also showed positive associations with receptive vocabulary, verbal memory, and reading comprehension. Some of the same regions showed weak negative correlations within the full-term group. Exploratory multiple regression in the preterm group found that specific white matter pathways were related to different aspects of language processing and reading, accounting for 27-44% of the variance. The findings suggest that higher performance in language and reading in a group of preterm but not full-term children is associated with higher fractional anisotropy of a bilateral and distributed white matter network.

Computerized neuropsychological testing to rapidly evaluate cognition in pediatric patients with neurologic disorders

Computerized neuropsychological tests represent a viable method for rapidly screening cognition. The purpose of this study was to explore performance on the CNS Vital Signs in a large pediatric neurology sample. Participants included 166 neurology patients (mean age, 13.0 years; standard deviation, 3.2) and 281 controls (mean age, 13.2 years; standard deviation, 3.2) between 7 and 19 years. The neurology sample performed significantly worse on all domain scores and nearly all subtest scores. Cohen d effect sizes were small to medium for verbal memory (d= 0.44), visual memory (d= 0.40), and reaction time (d= 0.48) and very large for psychomotor speed (d= 1.19), complex attention (d = 0.94), cognitive flexibility (d = 0.94), and the overall composite score (d = 1.08). Using the criterion for cognitive impairment of 2 or more scores ≤5th percentile, 36.6% of the neurology sample was identified as having an uncommon cognitive profile. This is the first study to demonstrate the performance of pediatric patients with neurologic disorders on CNS Vital Signs.

Hypertensive disorders in pregnancy and intellectual abilities in the offspring in young adulthood: the Helsinki Birth Cohort Study

BACKGROUND

Hypertensive disorders may affect the fetal developmental milieu and thus hint at mechanisms by which prenatal adversity associates with poorer intellectual ability in subsequent life.

AIM

We tested if hypertensive disorders in pregnancy are associated with intellectual ability in the offspring in young adulthood and if any potential associations between hypertensive disorders and intellectual abilities differ according to length of gestation, birth-weight, parity, and childhood socio-economic background.

METHODS

Using mothers' blood pressure and urinary protein measurements at maternity clinics and birth hospitals, we defined normotensive or hypertensive pregnancies in mothers of 1,196 men who participated in the Helsinki Birth Cohort 1934-1944 Study. At age 20 years the men completed a test on intellectual abilities during compulsory military service.

RESULTS

Participants born after pregnancies complicated by hypertensive disorders scored lower on intellectual abilities compared to those born after normotensive pregnancies. The effects of hypertensive disorders were most obvious in men born preterm or after a primiparous pregnancy and in men of higher childhood socio-economic background.

CONCLUSION

Hypertensive disorders in pregnancy are, albeit weakly, associated with lower intellectual abilities in the offspring. These findings are compatible with the concept of adverse fetal 'programming' by a suboptimal prenatal environment.

Motor learning and working memory in children born preterm: a systematic review

Children born preterm have a higher risk for developing motor, cognitive, and behavioral problems. Motor problems can occur in combination with working memory problems, and working memory is important for explicit learning of motor skills. The relation between motor learning and working memory has never been reviewed. The goal of this review was to provide an overview of motor learning, visual working memory and the role of working memory on motor learning in preterm children. A systematic review conducted in four databases identified 38 relevant articles, which were evaluated for methodological quality. Only 4 of 38 articles discussed motor learning in preterm children. Thirty-four studies reported on visual working memory; preterm birth affected performance on visual working memory tests. Information regarding motor learning and the role of working memory on the different components of motor learning was not available. Future research should address this issue. Insight in the relation between motor learning and visual working memory may contribute to the development of evidence based intervention programs for children born preterm.

Sport stacking activities in school children's motor skill development

This study examined the impact of a 12-wk. sport stacking intervention on reaction time (RT), manual dexterity, and hand-eye coordination in elementary school-aged children. 80 Grade 2 students participated in a 15-min. sport stacking practice session every school day for 12 wk., and were tested on psychomotor performance improvement. Tests for choice RT, manual dexterity, and photoelectric rotary pursuit tracking were conducted pre- and post-intervention for both experimental group (n = 36) and the controls (n = 44) who did no sport stacking. Students who had the intervention showed a greater improvement in two-choice RT. No other group difference was found. Such sport stacking activities may facilitate children's central processing and perceptual-motor integration.

Outcomes of preterm infants: morbidity replaces mortality

Over the last 50 years in the United States a rising preterm birth rate, a progressive decrease in preterm mortality, and a lowering of the limit of viability have made preterm birth a significant public health problem. Neuromaturation, the functional development of the central nervous system (CNS), is a dynamic process that promotes and shapes CNS structural development. This article reviews preterm outcomes, recognizing that multiple factors influence neuromaturation and lead to a range of neurodevelopmental disabilities, dysfunctions, and altered CNS processing. Ways to protect preterm infants and support their growth and development in and beyond intensive care are examined.

Specific language and reading skills in school-aged children and adolescents are associated with prematurity after controlling for IQ

Although studies of long-term outcomes of children born preterm consistently show low intelligence quotient (IQ) and visual-motor impairment, studies of their performance in language and reading have found inconsistent results. In this study, we examined which specific language and reading skills were associated with prematurity independent of the effects of gender, socioeconomic status (SES), and IQ. Participants from two study sites (N=100) included 9-16-year old children born before 36 weeks gestation and weighing less than 2500 grams (preterm group, n=65) compared to children born at 37 weeks gestation or more (full-term group, n=35). Children born preterm had significantly lower scores than full-term controls on Performance IQ, Verbal IQ, receptive and expressive language skills, syntactic comprehension, linguistic processing speed, verbal memory, decoding, and reading comprehension but not on receptive vocabulary. Using MANCOVA, we found that SES, IQ, and prematurity all contributed to the variance in scores on a set of six non-overlapping measures of language and reading. Simple regression analyses found that after controlling for SES and Performance IQ, the degree of prematurity as measured by gestational age group was a significant predictor of linguistic processing speed, β=-.27, p<.05, R(2)=.07, verbal memory, β=.31, p<.05, R(2)=.09, and reading comprehension, β=.28, p<.05, R(2)=.08, but not of receptive vocabulary, syntactic comprehension, or decoding. The language and reading domains where prematurity had a direct effect can be classified as fluid as opposed to crystallized functions and should be monitored in school-aged children and adolescents born preterm.

Adult outcome of extremely preterm infants

Survival rates for extremely preterm (<28 weeks' gestational age) infants have increased and are approaching 3 in 4 with the advent of modern perinatal and neonatal intensive care. In contrast with some children with chronic diseases such as cystic fibrosis, most survivors of extreme prematurity have no ongoing health issues. However, as a group, they do have higher rates of adverse health outcomes, and more of them will present to pediatricians over time and, ultimately, to adult physicians as they grow older. Pediatricians can aid the transition to adult health care by being aware of the nutritional, cardiovascular, respiratory, motor, cognitive, psychiatric, and functional outcomes into adulthood of survivors of extreme prematurity.