Academic achievement, behavioural outcomes and MRI findings at 15 years of age in very low birthweight children

Sex differences in the effects of prematurity and/or low birthweight on neurodevelopmental outcomes: systematic review and meta-analyses

BACKGROUND

Premature birth and/or low birthweight have long-lasting effects on cognition. The purpose of the present systematic review is to examine whether the effects of prematurity and/or low birth weight on neurodevelopmental outcomes differ between males and females.

METHODS

Web of Science, Scopus, and Ovid MEDLINE were searched for studies of humans born premature and/or of low birthweight, where neurodevelopmental phenotypes were measured at 1 year of age or older. Studies must have reported outcomes in such a way that it was possible to assess whether effects were greater in one sex than the other. Risk of bias was assessed using both the Newcastle-Ottawa scale and the National Institutes of Health Quality assessment tool for observational cohort and cross-sectional studies.

RESULTS

Seventy-five studies were included for descriptive synthesis, although only 24 presented data in a way that could be extracted for meta-analyses. Meta-analyses found that severe and moderate prematurity/low birthweight impaired cognitive function, and severe prematurity/low birthweight also increased internalizing problem scores. Moderate, but not severe, prematurity/low birthweight significantly increased externalizing problem scores. In no case did effects of prematurity/low birthweight differ between males and females. Heterogeneity among studies was generally high and significant, although age at assessment was not a significant moderator of effect. Descriptive synthesis did not identify an obvious excess or deficiency of male-biased or female-biased effects for any trait category. Individual study quality was generally good, and we found no evidence of publication bias.

CONCLUSIONS

We found no evidence that the sexes differ in their susceptibility to the effects of severe or moderate prematurity/low birthweight on cognitive function, internalizing traits or externalizing traits. Result heterogeneity tended to be high, but this reflects that one sex is not consistently more affected than the other. Frequently stated generalizations that one sex is more susceptible to prenatal adversity should be re-evaluated.

Self-reported mental health and cortisol activity at 27-28 years of age in individuals born with very low birthweight

Aim

To assess mental health outcomes of very low birthweight (VLBW, <1500 g) subjects to adulthood and to examine salivary cortisol and hair cortisol levels and their relation to birth characteristics and mental health.

Methods

A Swedish regional cohort of 56 VLBW subjects and 55 full‐term controls were assessed at the ages 27‐28 with adult self‐reported scales and the mean of 2 days diurnal salivary cortisol and hair cortisol. The cohorts had been assessed at 15 years of age with youth self‐reported scales.

Results

There were no differences between the groups in youth self‐reported scales and adult self‐reported scores. The 24 participating VLBW girls scored lower on youth self‐reported scales externalising and total problem scores than the control girls. In adulthood, the 21 participating VLBW women had significantly higher morning concentrations of salivary cortisol than control women, P = .014. No significant associations were found between cortisol concentrations and adult self‐reported scales internalising, externalising and total scores.

Conclusion

Self‐reported mental health in VLBW subjects was comparable with normal birthweight controls indicating a satisfying transition from adolescence to adulthood. VLBW females had higher morning salivary cortisol concentrations, suggesting a gender difference. We found no correlations between cortisol and mental health.

Oligogenesis in the "oligovascular unit" involves PI3K/AKT/mTOR signaling in hypoxic-ischemic neonatal mice

The "oligovascular unit" is a dynamic structural complex composed of endothelial cells (ECs) and oligodendrocyte progenitor cells (OPCs)/oligodendrocytes. By improving the microenvironment of OPCs in the "oligovascular unit" and promoting the proliferation and differentiation of OPCs, both myelination and white matter injury can be repaired. However, it is unclear what characteristic changes occur in the microenvironment of the "oligovascular unit" after preterm white matter injury (PWMI). Here, we demonstrate the changes in the "oligovascular unit" induced by hypoxia-ischemia (HI) and its underlying mechanism in PWMI mice. White matter injury and inhibited production of myelin from OPCs were observed by histopathological staining in HI neonatal mice. We further observed that the proliferation of OPCs and angiogenesis were increased after HI, which is considered the response of the body and cells to HI. HI-induced oligogenesis occurs around the vessels, indicating that "oligovascular units" exist and promote the proliferation and differentiation of OPCs after HI in the short term. We also determined that angiogenesis and oligogenesis induced by HI in the white matter are related to the PI3K/AKT/mTOR pathway. Furthermore, the myelin sheaths were shown to be disordered on the side of the surgery, and the myelin-dense layer was poorly developed at P14 and P28. Different degrees of damage to the vascular ECs and basement membrane on the surgical side were detected beginning at P4, indicating that EC injury is an early phenomenon that subsequently affects oligogenesis. Taken together, our findings indicate that the proliferation of OPCs and angiogenesis in white matter are increased in the early stage of HI involving PI3K/AKT/mTOR pathway activation. Promoting vascular endothelial function and angiogenesis may increase the proliferation and survival of OPCs via the "oligovascular unit," which suggests a potential method to repair injured white matter in the early stage of PWMI.

Language outcome related to brain structures in school-aged preterm children: A systematic review

Preterm children often have language problems. This atypical language development is probably due to atypical brain development. We conducted a systematic review to provide an overview of the extensive and diverse scientific literature on the relations between language outcome and underlying brain structures in school-aged preterm-born children. Embase, Medline Ovid, Web of Science, Cochrane central and Google scholar were searched for relevant studies. Inclusion criteria were: cases are school-aged preterm children; structural MRI (T1- and T2-weighted sequences) or DTI used in combination with a neurocognitive language test; publication in an English-language peer-reviewed journal. Correlational measures between language scores and brain volume or fractional anisotropy of a brain structure were extracted. 23 studies were included. The relations between oral language, verbal fluency and/or written language and MRI/DTI measurements of white matter, gray matter, cerebellum, corpus callosum and/or the fasciculi are presented. Oral language skills and verbal fluency appear to be related to the corpus callosum. Oral language skills are also related to the uncinate fasciculus. There seems to be no clear relation between cerebellar development and verbal fluency skills. Not one single brain area is responsible for atypical language development, but several brain areas and their connections are essential. For future research it is recommended to relate brain areas to oral language skills on a microstructural level in preterm children. We also recommend to use language tests in which it is possible to distinguish between several language domains, such as perceptive and expressive language.

Neurological Injury and Cerebral Blood Flow in Single Ventricles Throughout Staged Surgical Reconstruction

BACKGROUND

Patients with a single ventricle experience a high rate of brain injury and adverse neurodevelopmental outcome; however, the incidence of brain abnormalities throughout surgical reconstruction and their relationship with cerebral blood flow, oxygen delivery, and carbon dioxide reactivity remain unknown.

METHODS

Patients with a single ventricle were studied with magnetic resonance imaging scans immediately prior to bidirectional Glenn (pre-BDG), before Fontan (BDG), and then 3 to 9 months after Fontan reconstruction.

RESULTS

One hundred sixty-eight consecutive subjects recruited into the project underwent 235 scans: 63 pre-BDG (mean age, 4.8±1.7 months), 118 BDG (2.9±1.4 years), and 54 after Fontan (2.4±1.0 years). Nonacute ischemic white matter changes on T2-weighted imaging, focal tissue loss, and ventriculomegaly were all more commonly detected in BDG and Fontan compared with pre-BDG patients (P<0.05). BDG patients had significantly higher cerebral blood flow than did Fontan patients. The odds of discovering brain injury with adjustment for surgical stage as well as ≥2 coexisting lesions within a patient decreased (63%-75% and 44%, respectively) with increasing amount of cerebral blood flow (P<0.05). In general, there was no association of oxygen delivery (except for ventriculomegaly in the BDG group) or carbon dioxide reactivity with neurological injury.

CONCLUSIONS

Significant brain abnormalities are commonly present in patients with a single ventricle, and detection of these lesions increases as children progress through staged surgical reconstruction, with multiple coexisting lesions more common earlier than later. In addition, this study demonstrated that BDG patients had greater cerebral blood flow than did Fontan patients and that an inverse association exists of various indexes of cerebral blood flow with these brain lesions. However, CO₂ reactivity and oxygen delivery (with 1 exception) were not associated with brain lesion development.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT02135081.

Psychiatric diagnoses, emotional-behavioral symptoms and functional outcomes in adolescents born preterm with very low birth weights

Children born preterm with very low birth weight (VLBW; birth weight ≤1,500 g) run risks of neurodevelopmental disorders. Studies of adolescent outcome are relatively few. In this follow-up survey, we examined the emotional-behavioral symptoms, psychiatric diagnoses and functional status in a geographically-based birth cohort of VLBW adolescents (average 13.4 years) as registered in a level III center of a recently developed Asian country. Psychiatric interviews were conducted. Parents were asked to fill out the Child Behavioral Checklist and the Current Status Survey. Results revealed that neonatal survival rate was 75.7% (112/148). In the follow-up, 26.2% of the adolescents required individualized educational plan; 52.5% were with at least one neuropsychiatric diagnosis (e.g. cerebral palsy 24.6%, intellectual disabilities 21.3%, attention deficit/hyperactivity disorder 19.7%), and 32.8% of the participants were disabled. Logistic regression found that neonatal sepsis and grade III/IV intraventricular hemorrhage were most predictive of a disabled status in adolescence.

Behaviour problems and cortisol levels in very-low-birth-weight children

Abstract Background. There are still diverging results concerning the behaviour of children with very-low-birth-weight (VLBW) and they have been questioned to display different levels of stress hormone than normal-birth-weight (NBW) children. Aims. This study examined behaviour and the stress hormone cortisol in children with VLBW at the ages of 7 and 9 years compared with children with NBW. Results. Fifty-one VLBW and 50 NBW children were studied with the Child Behavior Checklist. Cortisol rhythm was measured through saliva samples three times a day for 2 days. VLBW children displayed more behavioural problems than NBW children, specifically social and attention problems, although still within normal ranges. They showed lower cortisol levels both at 7 and 9 years of age. No strong association between behaviour and cortisol levels was shown. Conclusion. VLBW children display more behaviour problems compared with NBW children but both groups score are within the normal range. Down-regulation of their hypothalamic-pituitary-adrenal (HPA) function in terms of lower cortisol levels is also noted.

Very low birthweight: dysregulated gestation versus evolutionary adaptation

Much medical literature attributes persistently high rates of very low birthweight (VLBW) to "dysregulated" gestation. We offer the alternative view that natural selection conserved well-regulated, though nonconscious, decisional biology that protects the reproductive fitness of women by spontaneously aborting gestations that would otherwise yield frail infants, particularly small males. Modern obstetric practice, however, converts some fraction of these erstwhile spontaneous abortions into live births of very small infants. We further propose that the nonconscious decisional biology of gestation exhibits preferences also seen in consciously made decisions. We hypothesize that the incidence of VLBW among male infants should vary with the population's self-reported intentions to assume financial risk. We apply time-series modeling to monthly birth counts by sex and weight from the Swedish Medical Birth Registry between January 1993 and December 2010. We gauge risk aversion with monthly data from the Micro Index of the Swedish Consumer Tendency Survey (MISCT). Consistent with our argument that nonconscious decisional biology shares risk aversion with conscious decisions, we find that the incidence of VLBW among male infants in Sweden varies with the population's self-reported intentions to assume financial risk. We find increases above expected odds of a very low weight infant among males born 1 month after increases above expected levels of self-reported risk aversion in the Swedish population. We offer this finding as support for the argument that persistently high rates of VLBW arise, at least in part, from a combination of medical interventions and mechanisms conserved by natural selection to protect reproductive fitness.

Relation of neural structure to persistently low academic achievement: a longitudinal study of children with differing birth weights

OBJECTIVE

This study examined the relation of cerebral tissue reductions associated with VLBW to patterns of growth in core academic domains.

METHOD

Children born <750 g, 750 to 1,499 g, or >2,500 g completed measures of calculation, mathematical problem solving, and word decoding at time points spanning middle childhood and adolescence. K. A. Espy, H. Fang, D. Charak, N. M. Minich, and H. G. Taylor (2009, Growth mixture modeling of academic achievement in children of varying birth weight risk, Neuropsychology, Vol. 23, pp. 460-474) used growth mixture modeling to identify two growth trajectories (clusters) for each academic domain: an average achievement trajectory and a persistently low trajectory. In this study, 97 of the same participants underwent magnetic resonance imaging (MRI) in late adolescence, and cerebral tissue volumes were used to predict the probability of low growth cluster membership for each domain.

RESULTS

Adjusting for whole brain volume (wbv), each 1-cm(3) reduction in caudate volume was associated with a 1.7- to 2.1-fold increase in the odds of low cluster membership for each domain. Each 1-mm(2) decrease in corpus callosum surface area increased these odds approximately 1.02-fold. Reduced cerebellar white matter volume was associated specifically with low calculation and decoding growth, and reduced cerebral white matter volume was associated with low calculation growth. Findings were similar when analyses were confined to the VLBW groups.

CONCLUSIONS

Reduced volume of structures involved in connectivity, executive attention, and motor control may contribute to heterogeneous academic trajectories among children with VLBW.

Low birth weight and intelligence in adolescence and early adulthood: a meta-analysis

BACKGROUND

Research has demonstrated an association between low birth weight (LBW; <2500 g) and adverse intelligence quotient (IQ) outcomes in childhood and early adolescence. We systematically evaluated whether this association persists into late adolescence and early adulthood and also assessed the influence of age of IQ assessment on effect size.

METHODS

During Stage 1 (meta-analysis of data on adolescents/adults), we searched for relevant articles in PsychINFO, PubMed, Ovid, CINAHL, ProQuest and ERIC until February 2011 (no lower limit). Studies which assessed full-scale IQ among LBW individuals (<2500 g), aged 13 years and older, with a normal birth weight (NBW; ≥2500 g) comparison group were eligible. A random-effects meta-analysis provided a pooled estimate of the difference in IQ scores between LBW and NBW individuals. Publication bias was assessed using Rosenthal's classic fail-safe N and Duval and Tweedie's Trim and Fill. During Stage 2, we added data from the Kerr-Wilson et al. meta-analysis (which included data from children; in Meta-analysis of the association between preterm delivery and intelligence. Journal Public Health 2011;33:1-8) to our sample from Stage 1 and conducted a meta-regression to evaluate the effect of age of IQ assessment.

RESULTS

Using a total of 15 studies in Stage 1, it was demonstrated that NBW individuals scored an average of 7.63 IQ points higher than LBW individuals, CI = 5.95-9.31. After adjusting for publication bias, NBW samples demonstrated an IQ of 4.98 points higher than LBW samples, CI = 3.20-6.77. Furthermore, age at IQ assessment was a significant moderator of the association between birth weight and IQ, in that the effect size decreased from childhood into young adulthood.

CONCLUSIONS

Cognitive impairments associated with LBW persist into adolescence and early adulthood; however, the influence of LBW on IQ decreases from childhood to young adulthood. These conclusions must be interpreted with caution due to unmeasured variables and possible influence from publication bias.

Follow-up studies of very low birthweight children in Sweden

Follow-up studies are essential to our knowledge of outcome in very low birthweight (VLBW) or extremely preterm (EPT) infants because those children have a greater risk for developing neurosensory disabilities and behavioural and educational problems and have decreased probability for an optimal transition into adulthood compared to term controls. Outcome data are of interest not only to healthcare professionals but also to parents, schoolteachers and society. The aim of this review is to describe the follow-up studies of seven populations of VLBW or EPT infants performed in Sweden and published between 1995 and 2009.

CONCLUSION

 The time has come to implement evident data from these Swedish follow-up studies into clinical practice and to perform regular and specific follow-up examinations during childhood for all VLBW and EPT children. These assessments, specially designed for high-risk infants, should consider the potential outcomes for neurological, visual, auditory function and cognitive function as well as behaviour and growth, from birth to school-start.

Adolescents born extremely preterm: behavioral outcomes and quality of life

Fifty-two extremely premature born and 54 full-term controls were assessed regarding behavioral outcomes, risk-taking and self-perceived quality of life. Behavioral outcomes were assessed with the Achenbach Youth Self Report; risk-taking was estimated regarding alcohol and nicotine use; self-perceived quality of life and future expectations were rated; and attention and hyperactivity problems were surveyed retrospectively with the Wender Utah Rating Scale. The prematurely born reported fewer problems than full-term born on the externalizing scale (delinquent behavior and aggressive behaviour); and they reported less alcohol consumption. No difference was observed between the two groups concerning nicotine use, views about quality of life and expectations for the future or in the retrospective assessment of attention and hyper-activity problems. Conclusively, the prematurely born adolescents described a quality of life and future expectations comparable to full-term born controls. They also reported fewer behavioral problems and less risk-taking behavior.

Dental fear and anxiety and oral health behaviour in 12- to 14-year-olds born preterm

BACKGROUND

An enhanced frequency of cognitive and behavioural disturbances has been reported in preterm children. It is not known if this affects their perceptions of or behaviour in the dental care situation.

HYPOTHESIS

The hypotheses were that preterm (PT) children aged 12-14 years more often exhibit dental fear and anxiety (DFA) than full-term controls (C), while no differences were expected regarding oral health behaviour.

METHODS

One hundred and nine PT and 108 C children took part in the present questionnaire study. DFA was assessed using the Children's Fear Survey Schedule - Dental Subscale (CFSS-DS). In addition the questionnaire covered items including satisfaction with received dental care, oral health behaviour and medical health.

RESULTS

The children's CFSS-DS scores revealed no differences between the PT and C groups. Regarding oral health behaviour there were no differences, except that PT children more often used dental floss and extra fluoride supplements. PT children reported more medical health problems than C children.

CONCLUSIONS

Preterm (PT) children 12- to 14-years-old, as well as C of same age group, seem to be satisfied with their dental care and display low prevalence of DFA. Still, a higher frequency of medical health problems in the PT children suggests that these children should be regarded as potential risk patients for oral health problems.

Most very low birth weight subjects do well as adults

AIM

To study health, quality of life, educational level and occupation in very low birth weight (VLBW) children in early adulthood and the relationship of the findings to neonatal risk factors and later handicap.

METHODS

This is a prospective long-term follow-up study of a regional cohort of 20-year-old VLBW subjects (n = 77) of all surviving VLBW children (n = 86) and 69/86 term controls born in 1987-1988 in the south-east of Sweden. Postal questionnaires were used: 1. A study-specific form, 2. Medical Outcomes Study, Short Form (SF-36), 3. Sense of Coherence.

RESULTS

VLBW subjects did not differ significantly from their controls in self-perceived health, use of tobacco, education, occupation and way of living, or scoring on SF-36 and Sense of Coherence. Sixteen had cerebral palsy, attention deficit hyperactivity disorder or isolated mental retardation, and these subjects differed significantly from controls on SF-36 in physical functioning and physical health score, but not on Sense of Coherence. VLBW subjects were significantly lighter and shorter than their controls. Extremely low birth weight (ELBW), bronchopulmonary dysplasia and intraventricular haemorrhage were significantly associated with poorer scores on physical function.

CONCLUSION

The 20-year old VLBW subjects reported perceived health and managed transition to adulthood similar to controls. Handicapped subjects had poorer self-perceived physical function. ELBW and severe neonatal complications were associated with poorer self-perceived physical health.

Predictors of neurodevelopmental outcome for preterm infants with brain injury: MRI, medical and environmental factors

This multi-center correlational prospective study examined early neonatal predictors of neurodevelopment in 59 premature infants (mean birth weight=1713.8+/-1242.5 g; mean gestational age=31.2+/-3.6 weeks) suspected to have sustained brain injury at birth. The mental and motor development of the infants selected from five university-affiliated hospitals was assessed at baseline (59 infants), 12 (55 infants), and 18 months (46 infants) using Bayley II scales. Factors correlating with Bayley II scores at 12 and 18 months included head circumference, results of neurological and magnetic resonance imaging (MRI) examination at baseline, environmental factors such as mother-infant interactions and levels of parental stress, and infant medical factors such as Apgar scores at 5 min and length of hospital stay. Multiple regression analyses distinguished the most significant predictors of mental and motor development. The best predictors of mental and motor development at 18 months were head circumference, neurological examinations, and MRI results. These findings suggest that in infants suspected of brain injury at birth, neurological assessments and head circumference measurements are just as predictive of developmental outcome at 18 months as MRI, and this is especially relevant in developing countries or other locations where MRI is not possible. The presence of this information may offer the potential of early tailored interventions to improve the mental and motor development of children in developing countries or other facilities where MRI is unavailable.