Factors affecting vocabulary acquisition at age 2 in children born between 23 and 28 weeks' gestation

Early Speech Sound Production and Its Trajectories in Very Preterm Children From 2 to 4 Years of Age

PURPOSE

Very preterm (VPT) children are at risk for speech and language problems throughout school age. However, little is known about early speech sound production in these children. This study aims to present a detailed description of early speech sound production and its trajectories in VPT children from 2 to 4 years of age. In addition, this study aimed to determine if early speech sound production is associated with speech production and expressive language function at 4 years of age.

METHOD

In 63 VPT children (< 32 weeks of gestation, 41 boys, mean gestational age = 28.8 weeks, mean birth weight = 1,135 g), speech sound production was assessed by naturalistic speech analysis at 2 years of corrected age and speech and language function by standardized tests at 4 years of age.

RESULTS

Speech sound production was found to be abnormal in 49% of the VPT children at 2 years of age and in 19% at 4 years of age. Four different speech production trajectories from 2 to 4 years of age could be identified: a normal trajectory, an abnormal trajectory, a catch-up trajectory, and a growing-into-deficit trajectory. Early speech production, defined by the number of acquired consonants at 2 years of age, significantly predicted the word production score at 4 years of age and the sentence production score at 4 years of age.

CONCLUSIONS

Compared to the general population, an alarmingly high proportion of VPT children showed speech production problems at 2 years of age. About half of these children showed persistent speech problems at 4 years of age. Moreover, these problems were associated with expressive language problems at the age of 4 years.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.19310822.

Validity of an early parent-report questionnaire for language disorder in very preterm children from 2 to 10 years of age

BACKGROUND

Language problems at an early age in very preterm (VP) children can have a detrimental effect on other developmental domains and often persist throughout childhood. The aim of this study was to examine the concurrent and predictive validity of an early language parent-report questionnaire for language disorder in VP children from 2 to 10 years of age.

MATERIALS AND METHODS

In 80 VP children (<32 weeks' gestation) without major disabilities, a parent-questionnaire and formal language assessment, both normed for the general population, were administered at 2 years corrected age (CA). Of these infants, 62 were seen for follow-up formal language assessment at age 4 and 61 were seen at age 10. Sensitivity and specificity values were calculated.

RESULTS

The Lexi-list showed acceptable concurrent validity for word production scores obtained at age 2 CA. The predictive validity was good for sentence production and acceptable for word production scores obtained at age 4, and low for language production scores obtained at age 10. A Lexi-list cut-off score of <85 (i.e., <-1 SD) was found optimal.

INTERPRETATION

A norm-referenced parent-report questionnaire is a useful, first screening tool in a neonatal follow-up. It not only detected early language disorder at age 2 CA but also proved to be a good predictor for language disorder at age 4. However, it did not predict language disorder at age 10. Formal language assessment at age 4 would therefore be recommended for children with an abnormal parent-report language score at age 2 CA.

Speech-Language Profile Groups in School Aged Children with Cerebral Palsy: Nonverbal Cognition, Receptive Language, Speech Intelligibility, and Motor Function

Purpose: To explore the relationship of intelligibility, receptive language, executive functioning, and motor skills to nonverbal cognitive skills among children with cerebral palsy (CP) in different speech-language profile groups. Method: Twenty-seven children with CP aged 10-12 years old participated in the study. They completed a battery of standard clinical assessments. The relationship of various skillsets with nonverbal cognitive ability was explored using correlational procedures. Additionally, we examined pairwise differences in nonverbal cognitive skills among profile groups. Cohen's Kappa and Chi-square tests were used to study the consistency of receptive language and nonverbal cognitive performance. Results: Children who showed better nonverbal cognitive abilities demonstrated better motor, receptive language, and intelligibility skills. Nonverbal cognition was generally consistent with receptive language. Conclusion: Nonverbal cognitive impairment often co-occurs with language and speech motor impairment among children with CP. Speech-language profile groups are a useful framework for describing both communication and cognitive abilities.

Maternal education and language development at 2 years corrected age in children born very preterm: results from a European population-based cohort study

BACKGROUND

Socioeconomic factors influence language development in the general population, but the association remains poorly documented in children born very preterm (VPT). We assessed the impact of maternal education on language development in children born VPT and effect modification by perinatal risk.

METHODS

Data were from the Effective Perinatal Intensive Care in Europe (EPICE) population-based cohort of children born <32 weeks' gestational age (GA) in 2011/2012. Regions from six countries (Estonia, France, Germany, Italy, Sweden and UK) used a validated short form MacArthur Developmental Communicative Inventories Checklist to assess language at 2 years corrected age. Perinatal variables were collected from clinical records. We assessed expressive language delay (ELD), defined as (a) not combining words; and (b) expressive vocabulary <10th percentile of norms for age and sex. Perinatal risk (low, moderate and high) was determined using GA, small for GA and neonatal morbidities. We estimated adjusted risk ratios (aRR) of ELD by maternal education with inverse weighting to account for non-response bias.

RESULTS

Of 2741 children, 24.6% were not combining words and 39.7% had a low expressive vocabulary. Low maternal education (lower secondary or less compared with a bachelor's degree or more) increased risks of ELD: not combining words: aRR=1.52 (95% CI 1.36 to 1.69); low expressive vocabulary: aRR=1.25 (1.04 to 1.51). For children with low perinatal risk, the aRR were 1.88 (1.26 to 2.80) and 1.44 (1.06 to 1.95), respectively, compared with those with high perinatal risks: 1.36 (1.10 to 1.67) and 1.11 (0.97 to 1.27), respectively.

CONCLUSION

Low maternal education affects ELD for children born VPT, although the association appears attenuated among those with highest perinatal risk.

Language Skills in Children Born Preterm (<30 Wks' Gestation) Throughout Childhood: Associations With Biological and Socioenvironmental Factors

OBJECTIVE

To examine the individual and collective contribution of biological and socioenvironmental factors associated with language function at 2, 5, 7, and 13 years in children born preterm (<30 weeks' gestation or <1250 g birth weight).

METHODS

Language function was assessed as part of a prospective longitudinal study of 224 children born preterm at 2, 5, 7, and 13 years using age-appropriate tools. Language Z-scores were generated based on a contemporaneous term-born control group. A selection of biological factors (sex, small for gestational age, bronchopulmonary dysplasia, infection, and qualitatively defined brain injury) and early socioenvironmental factors at age 2 years (primary income earner employment status and type, primary caregiver education level, English as a second language, parental mental health history, parent sensitivity and facilitation, and parent-child synchrony) was chosen a priori. Associations were assessed using univariable and multivariable linear regression models applied to outcomes at each time point.

RESULTS

Higher primary caregiver education level, greater parent-child synchrony, and parent sensitivity were independently associated with better language function across childhood. Socioenvironmental factors together explained an increasing percentage of the variance (9%-18%) in language function from 2 to 13 years of age. In comparison, there was little evidence for associations between biological factors and language function, even during early childhood years.

CONCLUSION

This study highlights the importance of socioenvironmental factors over biological factors for language development throughout childhood. Some of these socioenvironmental factors are potentially modifiable, and parent-based interventions addressing parenting practices and education may benefit preterm children's language development.

Association of Language Skills with Other Developmental Domains in Extremely, Very, and Moderately Preterm Children: EPIPAGE 2 Cohort Study

OBJECTIVE

To analyze language skills in children born at 24-34 weeks of gestation at 2 years of corrected age and the association between language and other developmental domains.

STUDY DESIGN

We included 2424 children (64% of the eligible population) from the French population-based EPIPAGE 2 cohort study. At 2 years' corrected age, children were screened with the French short version of the MacArthur-Bates Communication Developmental Inventories and the Ages and Stages Questionnaire completed by parents.

RESULTS

Small lexicon size, <10th percentile of the calibration sample (ie, 28 words in a list of 100) was observed in 135 of 300 children (45%) born at 23-26 weeks, 484 of 1513 (32%) born at 27-31 weeks, and 165 of 611 (27%) born at 32-34 weeks of gestation. Small lexicon size was associated with 2 other language measures: word combination use and the Ages and Stages Questionnaire communication domain score. It was also significantly associated with the Ages and Stages Questionnaire score below the threshold in the other developmental domains (gross motor function, fine motor function, problem solving skills, and personal social skills) for all gestational age groups, after adjustment for potential confounders. Overall, 46% of children with a small lexicon size had ≥1 of these domains below the threshold, as compared with only 22% of children without a small lexicon size.

CONCLUSIONS

These results highlight the usefulness of the MacArthur-Bates Communication Developmental Inventories in preterm children, especially those who do not participate in specialized follow-up. A small lexicon size points to developmental difficulties in language and increased risk for other developmental and neurobehavioral functions.

Persistent unexplained physical symptoms: a prospective longitudinal cohort study in UK primary care

BACKGROUND

Unexplained physical symptoms (UPS) are extremely common among primary care attenders, but little is known about their longer-term outcome.

AIM

To investigate the persistence of somatic symptoms at 6 months among a cohort with multiple UPS, and identify prognostic factors associated with worsening symptom scores.

DESIGN AND SETTING

Prospective longitudinal cohort study involving adults attending UK general practice in North and Central London between January and December 2013.

METHOD

Consecutive adults attending nine general practices were screened to identify those with at least three UPS. Eligible participants completed measures of symptom severity (measured using the Patient Health Questionnaire Somatic Symptom Module [PHQ-15]), physical and mental wellbeing, and past health and social history, and were followed up after 6 months. Multivariable linear regression analysis was conducted to identify prognostic factors associated with the primary outcome: somatic symptom severity.

RESULTS

Overall, 245/294 (83%) provided 6-month outcome data. Of these, 135/245 (55%) reported still having UPS, 103/245 (42%) had symptoms still under investigation, and only 26/245 (11%) reported complete symptom resolution. Being female, higher baseline somatic symptom severity, poorer physical functioning, experience of childhood physical abuse, and perception of poor financial wellbeing were significantly associated with higher somatic symptom severity scores at 6 months.

CONCLUSION

This study has shown that at 6 months few participants had complete resolution of unexplained somatic symptoms. GPs should be made aware of the likelihood of UPS persisting, and the factors that make this more likely, to inform decision making and care planning. There is a need to develop prognostic tools that can predict the risk of poor outcomes.

Nurturing the preterm infant brain: leveraging neuroplasticity to improve neurobehavioral outcomes

An intrinsic feature of the developing brain is high susceptibility to environmental influence-known as plasticity. Research indicates cascading disruption to neurological development following preterm (PT) birth; yet, the interactive effects of PT birth and plasticity remain unclear. It is possible that, with regard to neuropsychological outcomes in the PT population, plasticity is a double-edged sword. On one side, high plasticity of rapidly developing neural tissue makes the PT brain more vulnerable to injury resulting from events, including inflammation, hypoxia, and ischemia. On the other side, plasticity may be a mechanism through which positive experience can normalize neurological development for PT children. Much of the available literature on PT neurological development is clinically weighted and focused on diagnostic utility for predicting long-term outcomes. Although diagnostic utility is valuable, research establishing neuroprotective factors is equally beneficial. This review will: (1) detail specific mechanisms through which plasticity is adaptive or maladaptive depending on the experience; (2) integrate research from neuroimaging, intervention, and clinical science fields in a summary of findings suggesting inherent plasticity of the PT brain as a mechanism to improve child outcomes; and (3) summarize how responsive caregiving experiences situate parents as agents of change in normalizing PT infant brain development.

Neurodevelopmental Outcomes in Early Childhood

Technological advances in neonatal-perinatal medicine have led to a steady increase in the survival of preterm infants. Although the increase in survival is a remarkable success, children born preterm remain at high risk for brain injury and long-term neurodevelopmental deficits. Children born preterm may have abnormal muscle tone or movements, cognitive deficits, language impairments, and behavioral problems. This article reviews neurodevelopmental outcomes and factors that influence outcomes in preterm children during early childhood.

Risk Factor Models for Neurodevelopmental Outcomes in Children Born Very Preterm or With Very Low Birth Weight: A Systematic Review of Methodology and Reporting

The prediction of long-term outcomes in surviving infants born very preterm (VPT) or with very low birth weight (VLBW) is necessary to guide clinical management, provide information to parents, and help target and evaluate interventions. There is a large body of literature describing risk factor models for neurodevelopmental outcomes in VPT/VLBW children, yet few, if any, have been developed for use in routine clinical practice or adopted for use in research studies or policy evaluation. We sought to systematically review the methods and reporting of studies that have developed a multivariable risk factor model for neurodevelopment in surviving VPT/VLBW children. We searched the MEDLINE, Embase, and PsycINFO databases from January 1, 1990, to June 1, 2014, and identified 78 studies reporting 222 risk factor models. Most studies presented risk factor analyses that were not intended to be used for prediction, confirming that there is a dearth of specifically designed prognostic modeling studies for long-term outcomes in surviving VPT/VLBW children. We highlight the strengths and weaknesses of the research methodology and reporting to date, and provide recommendations for the design and analysis of future studies seeking to analyze risk prediction or develop prognostic models for VPT/VLBW children.

Influência de fatores de risco sobre o desenvolvimento da linguagem e contribuições da estimulação precoce: revisão integrativa da literatura

RESUMO O objetivo do estudo foi identificar evidências na literatura a respeito da influência dos fatores de risco sobre o desenvolvimento da linguagem da criança e as contribuições da estimulação precoce. Trata-se de uma revisão integrativa, que utilizou as bases de dados Lilacs, PubMed e SciELO e os descritores: linguagem infantil, fatores de risco, prematuro, criança pós-termo, índice de Apgar, estimulação precoce. A partir dos achados, extraíram-se os seguintes dados: autores, ano de publicação, objetivo, desenho do estudo, participantes e critérios, variáveis estudadas, principais achados. Para a organização e análise foi utilizada a técnica de Análise de Conteúdo do tipo temática. Foram identificados 1.421 artigos, 29 atenderam os critérios de inclusão. Os estudos foram categorizados por resultados afins; A maioria dos artigos selecionados trata do efeito da prematuridade sobre o desenvolvimento da linguagem. Quatro estudos investigaram a associação entre fatores de risco e problemas no desenvolvimento da linguagem. Um dos estudos avaliou crianças em idade escolar e associou valores de Apgar com DEL. Foi unanime a recomendação acerca do acompanhamento e intervenção precoce. Conclui-se que os fatores de risco elencados influenciam negativamente no desenvolvimento da linguagem. Reforça-se a recomendação do atendimento precoce e qualificado dessas crianças, evitando e/ou minimizando alterações futuras.

Language and hearing outcomes of preterm infants

Multiple factors including degree of prematurity, neonatal morbidities, illness severity, hearing status, gender, language environment in the neonatal intensive care unit and in the home, maternal education level, social and environmental status of the family, and access to early intervention all contribute to the language outcomes of extremely preterm infants with and without hearing loss. Early screening, early diagnosis, and early intervention services by 6 months of age are necessary to optimize the language outcomes of preterm infants with permanent hearing loss. There is increasing evidence of the potential for improved language skills with increasing age of extreme preterm infants and infants with hearing loss.

Receptive language and intellectual abilities in preterm children

OBJECTIVE

The aim of this study was to examine the association between receptive vocabulary performance and intellectual quotient (IQ) in preterm born children compared to children born at term.

METHOD

A total of 72 preschool-age children participated in the study. Participants were divided in four groups: EG-I, including 20 moderate to late preterm born children; EG-II, comprehending 16 extremely preterm born children; CG-I and CG-II with correspondingly 20 and 16 children born at term. EG-I and CG-I as well as EG-II and CG-II groups were matched according to gender, chronological age, and family SES. The mean age of children in each group was: EG-I and CG-I: 30.3months; EG-II and CG-II: 29.1months. The assessment information was collected using an anamnesis protocol, the Brazilian criterion of economic classification, the Peabody Picture Vocabulary Test, and the Stanford-Binet Intelligence Scale.

RESULTS

Mean scores for receptive vocabulary were significantly lower in both preterm groups (EG-I and EG-II) than in the corresponding matched groups (CG-I and CG-II). However, no significant differences were found among the preterm groups. Moreover, high correlations between vocabulary and IQ scores were found in both preterm groups (EG-I and EG-II). In contrast, no significant correlations were found when analyses considered each group of full-term born children (CG-I and CG-II).

CONCLUSION

Our findings indicate that prematurity status has an impact on receptive language performance and on the pattern of relationships between receptive vocabulary and general intellectual functioning.

Validity of the language development survey in infants born preterm

BACKGROUND

Preterm infants are at greater risk of language delay. Early identification of language delay is essential to improve functional outcome in these children.

AIM

To examine the concurrent validity of Rescorla's Language Development Survey and the Bayley Scales of Infant and Toddler Development (Bayley-III) at 18months corrected age in preterm infants.

STUDY DESIGN

Test accuracy study.

PARTICIPANTS

189 preterm infants born <29weeks were assessed at 18months.

OUTCOME MEASURES

The Language Development Survey, a parent-reported screening instrument, was administered in French concurrently with the Language Scales of the Bayley-III. Receiver-Operating-Characteristics curves were used to determine optimal cut-off score on the Language Development Survey to identify Bayley-III score <85. Sensitivity, specificity, positive and negative predictive values, and κ coefficient were calculated.

RESULTS

Using Rescorla's original cut-off scores of ≤10 words for boys and ≤24 for girls, sensitivity was 76% and 88% for boys and girls, respectively, and specificity was 73% and 52% for boys and girls, respectively, in identifying language delay as per the Bayley-III. The optimal threshold was ≤10 words for both boys and girls. In girls, lowering the cut-off score decreased sensitivity (79%), but improved specificity (82%), thus lowering the number of false-positives.

CONCLUSION

Our findings support using the Language Development Survey as an expressive language screener in preterm infants.

Prognostic Factors for Poor Cognitive Development in Children Born Very Preterm or With Very Low Birth Weight: A Systematic Review

IMPORTANCE

Cognitive delay is the most common form of impairment among children born very preterm (VPT) at 32 weeks or less or with very low birth weight (VLBW) of 1250 g or less. It is important to identify factors that are robust predictors of long-term outcome because the ability to predict future prognosis will assist in health care and educational service planning and provision.

OBJECTIVE

To identify prognostic factors for poor cognitive development in children born VPT or with VLBW.

EVIDENCE REVIEW

A systematic review was conducted using MEDLINE, EMBASE, and PyscINFO databases to identify studies published between January 1, 1990, and June 1, 2014, reporting multivariable prediction models for neurodevelopment in VPT or VLBW children. Thirty-one studies comprising 98 risk factor models for cognitive outcome were identified. Two independent reviewers extracted key information on study design, outcome definition, risk factor selection, model development, and reporting and conducted a risk-of-bias assessment.

FINDINGS

There was evidence that male sex, nonwhite race/ethnicity, lower level of parental education, and lower birth weight were predictive of global cognitive impairment in children younger than 5 years. In older children, only the influence of parental education was sustained. Male sex was also predictive of language impairment in early infancy, but not in middle childhood. Gestational age was a poor predictor of cognitive outcome, probably because of a reduced discriminatory power in cohorts restricted to a narrow gestational age range. The prognostic value of neonatal brain injury was unclear; however, studies adopted mixed strategies for managing children with physical or neurosensory disability.

CONCLUSIONS AND RELEVANCE

The influence of perinatal risk factors on cognitive development of VPT or VLBW children appears to diminish over time as environmental factors become more important. It is difficult to isolate cognitive outcomes from motor and neurosensory impairment, and the strategy for dealing with untestable children has implications for risk prediction.

Neurodevelopmental outcome after extreme prematurity: a review of the literature

BACKGROUND

Advances in obstetric and neonatal medical care and assisted reproductive technology have increased the rates of preterm birth, decreased preterm mortality rates, and lowered the limit of viability. However, morbidity in survivors, including neurodevelopmental disabilities, has increased, especially in extremely preterm infants born at ≤25 weeks' gestation. A better understanding of the prevalence and patterns of adverse neurodevelopmental outcomes in extremely preterm infants is important for patient care, counseling of families, and research.

METHODS

The PubMed and Ovid Medline databases were searched for full text articles published between 1999 and 2013 in English that reported neurodevelopmental outcomes after extreme prematurity, and a review of identified relevant cohort studies was performed.

RESULTS

Extreme prematurity of 22 to 25 weeks' gestation is associated with an overall high mortality of ≥50%. High rates (17% to 59%) of severe neurodevelopmental disabilities occur among survivors on short-term follow-up. The rates of surviving unimpaired or minimally impaired are 6% to 20% for live-born infants at ≤25 weeks' gestation and <5% for infants born at 22 and 23 weeks' gestation. Long-term adverse outcomes after extreme prematurity include intellectual disability (5% to 36%), cerebral palsy (9% to 18%), blindness (0.7% to 9%), and deafness (2% to 4%). Milder degrees of disability involving cognition, behavior, and learning are increasingly recognized among older preterm children, teens, and young adults.

CONCLUSIONS

Infants who are born at ≤25 weeks' gestation, especially those born at 22 and 23 weeks' gestation, have a very low likelihood of surviving little or no impairment. Nearly half of surviving extremely premature infants have significant neurodevelopmental disabilities on short- and long-term follow-up. Instituting early intervention programs, providing family support, and establishing special educational school programs can pay high dividends and lead to brighter futures and, hence, help improve neurodevelopmental outcome of preterm infants.

Language development of low risk preterm infants up to the age of 30 months

PURPOSE

To compare the lexical and grammatical development of a group of low risk preterm children with a group of full-term children at 10, 22, and 30 months of corrected age. In addition, the effect of possible determinant factors on linguistic development was investigated.

METHOD

An initial group of 150 low-risk PR children (mean GA: 32.62) and 49 FT children (mean GA: 39.70) recruited at birth were assessed at 10, 22, and 30 months of age. Communicative and linguistic abilities were measured at these three points in time through the CDI. Cognitive development and quality of family environment of the children, among other variables, were also assessed at 22 months of age. Hierarchical regression analyses were performed in order to test those factors which may contribute to prediction of language outcomes.

RESULTS

There was no significant delay in communicative, lexical or grammatical development of PR children. Even when comparisons were performed between fullterm and very preterm children, differences were not significant. Regression analyses indicate that gestures and early word comprehension predict very early word production development, but their effect disappears with time. The most important factors which predict language development at 30 months of age are previous cognitive scores and word production at 22 months of age. The results coming from group comparisons and from hierarchical regression analyses indicate that GA does not significantly affect language development from 10 to 30 months of age.

CONCLUSIONS

Low risk preterm toddlers do not seem to be delayed in their linguistic development.

Speech and language outcomes of very preterm infants

Speech and language impairments of both simple and complex language functions are common among former preterm infants. Risk factors include lower gestational age and increasing illness severity including severe brain injury. Even in the absence of brain injury, however, altered brain maturation and vulnerability imposed by premature entrance to the extrauterine environment is associated with brain structural and microstructural changes. These alterations are associated with language impairments with lasting effects in childhood and adolescence and increased needs for speech therapy and education supports. Studies are needed to investigate language interventions which begin in the neonatal intensive care unit.

Expressive language skills in Finnish two-year-old extremely- and very-low-birth-weight preterm children

OBJECTIVE

Preterm children with low birth weight are at greater risk of experiencing speech and language difficulties than full-term children. The aim of the current study was to investigate expressive language skills of Finnish-speaking preterm children with low birth weight [extremely-low-birth-weight (ELBW) children: n = 8; very-low-birth-weight (VLBW) children: n = 10] at 2 years of corrected age and to compare their language results with full-term controls (n = 18), using spontaneous speech samples.

METHODS

The children were video recorded in semistructured free-play sessions with their mothers. From these video samples, expressive vocabulary size and maximum sentence length (MSL) were analyzed. In addition, the possible effect of children's gender on language measures as well as associations between different language measures were examined.

RESULTS

The results showed that there was no statistically significant difference between the preterm and full-term groups in the size of expressive vocabulary. In contrast, the MSL, which measures morphosyntactic skills, was significantly shorter in preterm children. A positive correlation was found between MSL and expressive vocabulary. Children's gender was not associated with language skills measured.

CONCLUSION

The findings indicate that Finnish-speaking preterm children, especially ELBW children, experience difficulties in morphosyntactic skills.

Biological and environmental factors as predictors of language skills in very preterm children at 5 years of age

OBJECTIVE

Language problems are thought to occur more frequently in very preterm children compared with healthy term born children. The primary aim of this study was to examine the contributions of biological and environmental risk factors to language outcomes in very preterm children at 5 years of age.

METHODS

A cohort of 227 very preterm infants (birth weight <1250 g or gestational age <30 weeks) were recruited at birth and followed up at 2 and 5 years of age (corrected for prematurity) in a prospective, longitudinal study in Melbourne, Australia. Outcomes at 5 years of age were the Expressive and Receptive Language Scales from the Kaufman Survey of Early Academic and Language Skills. A range of hypothesized biological and environmental factors identified from past research were examined as predictors of language outcomes at 5 years of age using linear regression models.

RESULTS

Lower maternal education and poorer communication skills in the child at 2 years of age were predictive of poorer expressive and poorer receptive language outcomes at 5 years of age. Lower expressive language scores were also associated with the presence of moderate-severe white matter abnormalities on neonatal magnetic resonance imaging.

CONCLUSIONS

Results support the role of both biological and environmental factors in the evolution of language difficulties and highlight the need to consider these factors in the follow-up of preterm infants.

The influence of biological, social, and developmental factors on language acquisition in pre-term born children

The objective of this study is to evaluate language outcome in pre-term children, considering multiple factors. The hypothesis is that early communicative capacity (pre-verbal communicative utterances) is affected mainly by biological (prematurity, birth weight, and gender) and social factors (maternal education), while more advanced linguistic abilities (i.e., combinatorial and syntactic abilities) are mostly influenced by previously acquired communicative abilities. Eighteen monolingual Italian pre-term children (birth weight between 750 and 1600 grams, gestational age <37 weeks; 13 males and five females) were compared with a control group of 18 age-matched full-term children (8 males, 10 females). The longitudinal design comprised motor and cognitive assessment at 14 and 36 months, and communicative evaluation by direct observation at 14, 24, 30, and 36 months, and by indirect observation at 24 and 30 months. The main results evidenced were delayed development in pre-term compared to full-term children, particularly after 24 months of age; intra-individual differences in the pre-term group; and a strong effect of prematurity on communicative ability at 14 and 24 months; however, more advanced communicative developmental stages were influenced both by prematurity and by previously acquired linguistic skills.

Multiscale modeling of structural dynamics underlying force generation and product release in actomyosin complex

To decrypt the mechanistic basis of myosin motor function, it is essential to probe the conformational changes in actomyosin with high spatial and temporal resolutions. In a computational effort to meet this challenge, we have performed a multiscale modeling of the allosteric couplings and transition pathway of actomyosin complex by combining coarse-grained modeling of the entire complex with all-atom molecular dynamics simulations of the active site. Our modeling of allosteric couplings at the pre-powerstroke state has pinpointed key actin-activated couplings to distant myosin parts which are critical to force generation and the sequential release of phosphate and ADP. At the post-powerstroke state, we have identified isoform-dependent couplings which underlie the reciprocal coupling between actin binding and nucleotide binding in fast Myosin II, and load-dependent ADP release in Myosin V. Our modeling of transition pathway during powerstroke has outlined a clear sequence of structural events triggered by actin binding, which lead to subsequent force generation, twisting of central beta-sheet, and the sequential release of phosphate and ADP. Finally we have performed atomistic simulations of active-site dynamics based on an on-path "transition-state" myosin conformation, which has revealed significantly weakened coordination of phosphate by Switch II, and a disrupted key salt bridge between Switch I and II. Meanwhile, the coordination of MgADP by Switch I and P loop is less perturbed. As a result, the phosphate can be released prior to MgADP. This study has shed new lights on the controversy over the structural mechanism of actin-activated phosphate release and force generation in myosin motor.

Comparing methods of analysing datasets with small clusters: case studies using four paediatric datasets

Studies of prematurely born infants contain a relatively large percentage of multiple births, so the resulting data have a hierarchical structure with small clusters of size 1, 2 or 3. Ignoring the clustering may lead to incorrect inferences. The aim of this study was to compare statistical methods which can be used to analyse such data: generalised estimating equations, multilevel models, multiple linear regression and logistic regression. Four datasets which differed in total size and in percentage of multiple births (n = 254, multiple 18%; n = 176, multiple 9%; n = 10 098, multiple 3%; n = 1585, multiple 8%) were analysed. With the continuous outcome, two-level models produced similar results in the larger dataset, while generalised least squares multilevel modelling (ML GLS 'xtreg' in Stata) and maximum likelihood multilevel modelling (ML MLE 'xtmixed' in Stata) produced divergent estimates using the smaller dataset. For the dichotomous outcome, most methods, except generalised least squares multilevel modelling (ML GH 'xtlogit' in Stata) gave similar odds ratios and 95% confidence intervals within datasets. For the continuous outcome, our results suggest using multilevel modelling. We conclude that generalised least squares multilevel modelling (ML GLS 'xtreg' in Stata) and maximum likelihood multilevel modelling (ML MLE 'xtmixed' in Stata) should be used with caution when the dataset is small. Where the outcome is dichotomous and there is a relatively large percentage of non-independent data, it is recommended that these are accounted for in analyses using logistic regression with adjusted standard errors or multilevel modelling. If, however, the dataset has a small percentage of clusters greater than size 1 (e.g. a population dataset of children where there are few multiples) there appears to be less need to adjust for clustering.

Neurodevelopmental outcomes of preterm infants

PURPOSE OF REVIEW

Preterm birth is emerging as a major public health problem in the USA. Improvements in preterm birth and survival rates translate to increasing numbers of preterm survivors, and many develop motor, cognitive and sensory impairments.

RECENT FINDINGS

The review discusses the recently reported prevalence of neurodevelopmental disabilities in preterm survivors, in addition to studies of factors associated with neurodevelopmental outcome.

SUMMARY

A 2007 report from the Institute of Medicine emphasizes preterm birth as an increasingly common complex condition with multiple risk factors resulting from multiple gene-environmental interactions, leading to birth before 37 weeks gestation, neonatal complications and a disproportionately high contribution to neurodevelopmental disability rates. The increased risk of cerebral palsy with decreasing gestational age categories is well documented, but recent studies highlight the range and severity of cognitive, sensory, language, visual-perceptual, attention and learning deficits in very preterm children. Combined with increasingly sophisticated neuroimaging studies to identify perinatal risk factors, neurodevelopmental follow-up of neonatal intensive care unit trials offers the potential to really improve our understanding of how the preterm brain develops, is injured and recovers from injuries. Knowledge of what influences neurodevelopmental outcomes is key to developing better treatment strategies.