Positive screening for autism in ex-preterm infants: prevalence and risk factors

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.

Infants born late/moderately preterm are at increased risk for a positive autism screen at 2 years of age

OBJECTIVES

To assess the prevalence of positive screens using the Modified Checklist for Autism in Toddlers (M-CHAT) questionnaire and follow-up interview in late and moderately preterm (LMPT; 32-36 weeks) infants and term-born controls.

STUDY DESIGN

Population-based prospective cohort study of 1130 LMPT and 1255 term-born infants. Parents completed the M-CHAT questionnaire at 2-years corrected age. Parents of infants with positive questionnaire screens were followed up with a telephone interview to clarify failed items. The M-CHAT questionnaire was re-scored, and infants were classified as true or false positives. Neurosensory, cognitive, and behavioral outcomes were assessed using parent report.

RESULTS

Parents of 634 (57%) LMPT and 761 (62%) term-born infants completed the M-CHAT questionnaire. LMPT infants had significantly higher risk of a positive questionnaire screen compared with controls (14.5% vs 9.2%; relative risk [RR] 1.58; 95% CI 1.18, 2.11). After follow-up, significantly more LMPT infants than controls had a true positive screen (2.4% vs 0.5%; RR 4.52; 1.51, 13.56). This remained significant after excluding infants with neurosensory impairments (2.0% vs 0.5%; RR 3.67; 1.19, 11.3).

CONCLUSIONS

LMPT infants are at significantly increased risk for positive autistic screen. An M-CHAT follow-up interview is essential as screening for autism spectrum disorders is especially confounded in preterm populations. Infants with false positive screens are at risk for cognitive and behavioral problems.

Thalamic alterations in preterm neonates and their relation to ventral striatum disturbances revealed by a combined shape and pose analysis

Finding the neuroanatomical correlates of prematurity is vital to understanding which structures are affected, and to designing efficient prevention and treatment strategies. Converging results reveal that thalamic abnormalities are important indicators of prematurity. However, little is known about the localization of the abnormalities within the subnuclei of the thalamus, or on the association of altered thalamic development with other deep gray matter disturbances. Here, we aim to investigate the effect of prematurity on the thalamus and the putamen in the neonatal brain, and further investigate the associated abnormalities between these two structures. Using brain structural magnetic resonance imaging, we perform a novel combined shape and pose analysis of the thalamus and putamen between 17 preterm (41.12 ± 5.08 weeks) and 19 term-born (45.51 ± 5.40 weeks) neonates at term equivalent age. We also perform a set of correlation analyses between the thalamus and the putamen, based on the surface and pose results. We locate significant alterations on specific surface regions such as the anterior and ventral anterior (VA) thalamic nuclei, and significant relative pose changes of the left thalamus and the right putamen. In addition, we detect significant association between the thalamus and the putamen for both surface and pose parameters. The regions that are significantly associated include the VA, and the anterior and inferior putamen. We detect statistically significant surface deformations and pose changes on the thalamus and putamen, and for the first time, demonstrate the feasibility of using relative pose parameters as indicators for prematurity in neonates. Our methods show that regional abnormalities of the thalamus are associated with alterations of the putamen, possibly due to disturbed development of shared pre-frontal connectivity. More specifically, the significantly correlated regions in these two structures point to frontal-subcortical pathways including the dorsolateral prefrontal-subcortical circuit, the lateral orbitofrontal-subcortical circuit, the motor circuit, and the oculomotor circuit. These findings reveal new insight into potential subcortical structural covariates for poor neurodevelopmental outcomes in the preterm population.

Phenotypic differences in individuals with autism spectrum disorder born preterm and at term gestation

The objective of the study was to characterize the phenotype of males and females with autism spectrum disorder born preterm versus those born at term. Descriptive statistical analyses identified differences between male and female autism spectrum disorder subjects born preterm compared to term for several phenotypic characteristics and comorbidities. Of the 115 (13.0% of 883) born preterm, a greater percentage of males had sleep apnea (13.8% vs. 2.5%, p < 0.0001), seizure disorders (17.0% vs. 8.5%, p = 0.01), and attention-deficit/hyperactivity disorder (14.9% vs. 6.6%, p = 0.005). Females born preterm were more likely to be nonverbal (22.2% vs. 4.6%, p = 0.001). In summary, phenotypic differences were observed, especially among males. The results may have implications for understanding the underpinnings of a subset of individuals with autism spectrum disorder and contribute to the development of focused treatments for autism spectrum disorder among children born preterm.

Social perception in children born at very low birthweight and its relationship with social/behavioral outcomes

BACKGROUND

Research has shown that children born very prematurely are at substantially elevated risk for social and behavioral difficulties similar to those seen in full-term children with autism spectrum disorders (ASDs).

METHODS

To gain insight into core deficits that may underlie these difficulties, in this study, we assessed the social perceptual skills of 8- to 11-year-old children born at very low birthweight (VLBW) (<1,500 g) and age-matched, full-term controls, using the Child and Adolescent Social Perception Measure. We also assessed social and behavioral outcomes with two parent-report measures used in ASD screening.

RESULTS

Children in the preterm group had normal range estimated verbal IQ. However, we found that they were impaired in their ability to use nonverbal cues from moving faces and bodies, and situational cues, to correctly identify the emotions of characters depicted in videotaped social interactions. Their performance on this task was related to the number of 'autistic-like' traits they displayed.

CONCLUSIONS

This research highlights links between social perceptual deficits and poor social and behavioral outcomes in children born very prematurely. The results also suggest that even those who have escaped major intellectual/language problems are at risk for social and behavioral problems that can be of clinical concern.

Gaze Following Is Accelerated in Healthy Preterm Infants

Gaze following is an essential human communication cue that orients the attention of two interacting people to the same external object. This capability is robustly observed after 7 months of age in full-term infants. Do healthy preterm infants benefit from their early exposure to face-to-face interactions with other humans to acquire this capacity sooner than full-term infants of the same chronological age, despite their immature brains? In two different experiments, we demonstrated that 7-month-old preterm infants performed like 7-month-old full-term infants (with whom they shared the same chronological age) and not like 4-month-old full-term infants (with whom they shared the same postmenstrual age). The duration of exposure to visual experience thus appears to have a greater impact on the development of early gaze following than does postmenstrual age.

Local and global aspects of biological motion perception in children born at very low birth weight

Biological motion perception can be assessed using a variety of tasks. In the present study, 8- to 11-year-old children born prematurely at very low birth weight (<1500 g) and matched, full-term controls completed tasks that required the extraction of local motion cues, the ability to perceptually group these cues to extract information about body structure, and the ability to carry out higher order processes required for action recognition and person identification. Preterm children exhibited difficulties in all 4 aspects of biological motion perception. However, intercorrelations between test scores were weak in both full-term and preterm children--a finding that supports the view that these processes are relatively independent. Preterm children also displayed more autistic-like traits than full-term peers. In preterm (but not full-term) children, these traits were negatively correlated with performance in the task requiring structure-from-motion processing, r(30) = -.36, p < .05), but positively correlated with the ability to extract identity, r(30) = .45, p < .05). These findings extend previous reports of vulnerability in systems involved in processing dynamic cues in preterm children and suggest that a core deficit in social perception/cognition may contribute to the development of the social and behavioral difficulties even in members of this population who are functioning within the normal range intellectually. The results could inform the development of screening, diagnostic, and intervention tools.

Social attribution skills of children born preterm at very low birth weight

Children born prematurely at very low birth weight (<1500 g) are at increased risk for impairments affecting social functioning, including autism spectrum disorders (e.g., Johnson et al., 2010). In the current study, we used the Happé-Frith animated triangles task (Abell, Happé, & Frith, 2000) to study social attribution skills in this population. In this task, typical viewers attribute intentionality and mental states to shapes, based on characteristics of their movements. Participants included 34 preterm children and 36 full-term controls, aged 8-11 years. Groups were comparable in terms of age at test, gender, handedness, and socioeconomic status; they also performed similarly on tests of selective attention/processing speed and verbal intelligence. Relative to full-term peers, preterm children's descriptions of the animations were less appropriate overall; they also overattributed intentionality/mental states to randomly moving shapes and underattributed intentionality/mental states to shapes that seemed to be interacting socially. Impairments in the ability to infer the putative mental states of triangles from movement cues alone were most evident in children displaying more "autistic-like" traits, and this may reflect atypical development of and/or functioning in, or atypical connections between, parts of the social brain.

Participation and enjoyment of leisure activities in adolescents born at ≤ 29 week gestation

BACKGROUND AND OBJECTIVES

Motor, cognitive, social and behavioral problems have been found to persist in adolescents born extremely preterm. Leisure participation has been associated with health benefits; however, few studies have explored leisure participation in this population. The aim of this study was to describe leisure participation in adolescents born at ≤29week gestation. Secondary aims were to identify potential differences in participation related to sex, age, motor competence, and cognitive ability, and between adolescents born preterm and their siblings born at term.

METHODS

This cross-sectional study included 128 adolescents (mean age: 16.0years; 67 females) with a mean gestational age of 26.5weeks. All participants, as well as 22 siblings born at term, completed the Children's Assessment of Participation and Enjoyment.

RESULTS

Participation levels were highest in social and recreational activities, and lowest in active-physical and skill-based activities. Boys participated in more active-physical activities (p=0.01) and more often (p<0.001) than girls, whereas girls had higher participation levels in social and self-improvement activities (p<0.05) than boys. Older adolescents engaged in more social activities (p=0.01) and more frequently (p=0.002) than younger adolescents. Overall, participants with poor motor and cognitive skills had lower participation levels in active-physical and social activities. Adolescents born preterm participated in fewer recreational activities compared to term-born siblings (p=0.013).

CONCLUSIONS

Engagement in active-physical and skill-based leisure activities needs to be promoted in boys, and especially in girls with a history of prematurity. Activities should be adapted to sex and individual skill level in order to promote participation.

Distinct regions of the cerebellum show gray matter decreases in autism, ADHD, and developmental dyslexia

Differences in cerebellar structure have been identified in autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD), and developmental dyslexia. However, it is not clear if different cerebellar regions are involved in each disorder, and thus whether cerebellar anatomical differences reflect a generic developmental vulnerability or disorder-specific characteristics. To clarify this, we conducted an anatomic likelihood estimate (ALE) meta-analysis on voxel-based morphometry (VBM) studies which compared ASD (17 studies), ADHD (10 studies), and dyslexic (10 studies) participants with age-matched typically-developing (TD) controls. A second ALE analysis included studies in which the cerebellum was a region of interest (ROI). There were no regions of significantly increased gray matter (GM) in the cerebellum in ASD, ADHD, or dyslexia. Data from ASD studies revealed reduced GM in the inferior cerebellar vermis (lobule IX), left lobule VIIIB, and right Crus I. In ADHD, significantly decreased GM was found bilaterally in lobule IX, whereas participants with developmental dyslexia showed GM decreases in left lobule VI. There was no overlap between the cerebellar clusters identified in each disorder. We evaluated the functional significance of the regions revealed in both whole-brain and cerebellar ROI ALE analyses using Buckner and colleagues' 7-network functional connectivity map available in the SUIT cerebellar atlas. The cerebellar regions identified in ASD showed functional connectivity with frontoparietal, default mode, somatomotor, and limbic networks; in ADHD, the clusters were part of dorsal and ventral attention networks; and in dyslexia, the clusters involved ventral attention, frontoparietal, and default mode networks. The results suggest that different cerebellar regions are affected in ASD, ADHD, and dyslexia, and these cerebellar regions participate in functional networks that are consistent with the characteristic symptoms of each disorder.

Feasibility and validity of early screening for identifying infants with poor social-communication development in a well-baby clinic system

This study examined the feasibility and validity of implementing an autism spectrum disorders (ASD) screening for 12-month-old infants.

METHOD

Parents of 583 infants, 12months of age attending well baby clinics (WBCs), completed the First Year Inventory-Lite (FYI-L). Ten infants who failed the FYI-L and a subset of 12 infants who passed the identified FYI-L were evaluated using the Autism Observation Scale for Infants (AOSI) and the Mullen Scales of Early Learning. Information regarding social-communication development ≥24months of age was extracted from medical records of 153 of the 583 infants.

RESULTS

Mean response rate across clinics was 26.63%. Infants at risk compared to controls showed significantly higher scores on the AOSI, lower composite scores on the MSEL, and a higher rate of referral for a developmental evaluation. At 24months, 95% of infants who were negatively screened had no social-communication problems on their medical records; 60% of those who were screened positive had documented problems on medical records.

CONCLUSION

ASD screening using the FYI-L at 12months in a healthcare setting identifies infants with poor social-communication development, yet parents had low compliance with screening.

Growing up after extremely preterm birth: lifespan mental health outcomes

There is growing interest in the long-term mental health sequelae of extremely preterm birth. In this paper we review literature relating to mental health outcomes across the lifespan. Studies conducted in the preschool years, school age and adolescence, and adulthood show continuity in outcomes and point to an increased risk for inattention, socio-communicative problems and emotional difficulties in individuals born extremely preterm. Both behavioural and neuroimaging studies also provide evidence of a neurodevelopmental origin for mental health disorders in this population. Here we summarise contemporary evidence and highlight key methodological considerations for carrying out and interpreting studies in this field.

Prevalence and neonatal factors associated with autism spectrum disorders in preterm infants

OBJECTIVES

To determine the prevalence of autism spectrum disorders (ASD) across gestational age, examine the risk of ASD by gestational age controlling for other risk factors, and identify potential risk factors in the neonatal intensive care unit.

STUDY DESIGN

A retrospective cohort of infants born at ≥ 24 weeks between January 1, 2000, and December 31, 2007 at 11 Kaiser Permanente Northern California hospitals (n = 195,021). ASD cases were defined by a diagnosis made at a Kaiser Permanente ASD evaluation center, by a clinical specialist, or by a pediatrician. Cox proportional hazards regression models were used to evaluate the association between gestational age and ASD as well as potential risk factors in the neonatal intensive care unit and ASD.

RESULTS

The prevalence of ASD in infants <37 weeks was 1.78% compared with 1.22% in infants born ≥ 37 weeks (P < .001). Compared with term infants, infants born at 24-26 weeks had an adjusted hazard ratio (HR) for a diagnosis of ASD of 2.7 (95% CI 1.5-5.0). Infants born at 27-33 weeks (adjusted HR 1.4, 95% CI 1.1-1.8) and 34-36 weeks (adjusted HR 1.3, 95% CI 1.1-1.4) were also at increased risk. High frequency ventilation and intracranial hemorrhage were associated with ASD in infants < 34 weeks.

CONCLUSIONS

ASD was ~ 3 times more prevalent in infants <27 weeks compared with term infants. Each week of shorter gestation was associated with an increased risk of ASD. High frequency ventilation and intracranial hemorrhage were associated with ASD among infants <34 weeks.

Evaluation of early childhood social-communication difficulties in children born preterm using the Quantitative Checklist for Autism in Toddlers

OBJECTIVES

To characterize early childhood social-communication skills and autistic traits in children born very preterm using the Quantitative Checklist for Autism in Toddlers (Q-CHAT) and explore neonatal and sociodemographic factors associated with Q-CHAT scores.

STUDY DESIGN

Parents of children born before 30 weeks gestation and enrolled in a study evaluating routinely collected neurodevelopmental data between the post-menstrual ages of 20 and 28 months were invited to complete the Q-CHAT questionnaire. Children with severe neurosensory disabilities and cerebral palsy were excluded. Participants received neurodevelopmental assessments using the Bayley Scales of Infant and Toddler Development, 3rd edition (Bayley-III). Q-CHAT scores of this preterm cohort were compared with published general population scores. The association between Bayley-III cognitive and language scores and neonatal and sociodemographic factors with Q-CHAT scores were examined.

RESULTS

Q-CHAT questionnaires were completed from 141 participants. At a mean post-menstrual age of 24 months, the Q-CHAT scores of the preterm cohort (mean 33.7, SD 8.3) were significantly higher than published general population scores (mean 26.7; SD 7.8), indicating greater social-communication difficulty and autistic behavior. Preterm children received higher scores, particularly in the categories of restricted, repetitive, stereotyped behavior, communication, and sensory abnormalities. Lower Bayley-III language scores and non-white ethnicity were associated with higher Q-CHAT scores.

CONCLUSIONS

Preterm children display greater social-communication difficulty and autistic behavior than the general population in early childhood as assessed by the Q-CHAT. The implications for longer-term outcome will be important to assess.

Screening for autism in preterm children with extremely low and very low birth weight

BACKGROUND

Studies of children with very low birth weight (VLBW, 1,000-1,500 g) and extremely low birth weight (ELBW, less than 1,000 g) indicate that this population seems to be at increased risk of autism spectrum disorder (ASD).

METHODS

Parents of 101 VLBW and ELBW children (age 2 years, corrected for prematurity) agreed to participate in the study and signed informed consents; however, parents of only 75 children (44 boys, 31 girls) completed the screening questionnaires. The screening battery included the Modified Checklist for Autism in Toddlers (M-CHAT), Communication and Symbolic Behavior Scales Developmental Profile Infant-Toddler Checklist (CSBS-DP-ITC), and the Infant/Toddler Sensory Profile (ITSP). Children with disabilities were excluded. All children who screened positive on any of the screening tools were subsequently invited for a detailed assessment.

RESULTS

Thirty-two children (42.7%) screened positive on at least one of the screening questionnaires. The screening tool with the most positive results was the CSBS-DP-ITC (26 positive screens), followed by the M-CHAT (19 positive screens) and the ITSP (11 positive screens). Of the 32 children who tested positive, 19 participated in the detailed follow-up assessment. A diagnosis of ASD was confirmed in eight of the 19 children. ASD prevalence, calculated from those 19 children and those with negative screening results (43 children), yielded a prevalence of 12.9% in the sample. The difference in frequency of positive screens between the tests was significant (P=0.011). In pair comparisons, ITSP was found to be significantly less positive than CSBS-DP-ITC (P=0.032). No significant differences were found between the M-CHAT and CSBS-DP-ITC or between the M-CHAT and ITSP.

CONCLUSION

The results strongly support the hypothesis of an increased prevalence of autism in children with a birth weight less than 1,500 g.

Future directions for research in autism spectrum disorders

This article suggests future directions for research aimed at improving our understanding of the etiology and pathophysiology of autism spectrum disorder (ASD) as well as pharmacologic and psychosocial interventions for ASD across the lifespan. The past few years have witnessed unprecedented transformations in the understanding of ASD neurobiology, genetics, early identification, and early intervention. However, recent increases in ASD prevalence estimates highlight the urgent need for continued efforts to translate novel ASD discoveries into effective interventions for all individuals with ASD. In this article we highlight promising areas for ongoing and new research expected to quicken the pace of scientific discovery and ultimately the translation of research findings into accessible and empirically supported interventions for those with ASD. We highlight emerging research in the following domains as particularly promising and pressing: (a) preclinical models, (b) experimental therapeutics, (c) early identification and intervention, (d) psychiatric comorbidities and the Research Domain Criteria initiative, (e) ecological momentary assessment, (f) neurotechnologies, and (g) the needs of adults with ASD. Increased research emphasis in these areas has the potential to hasten the translation of knowledge on the etiological mechanisms of ASD to psychosocial and biological interventions to reduce the burden of ASD on affected individuals and their families.

Effects of intra-amniotic lipopolysaccharide and maternal betamethasone on brain inflammation in fetal sheep

Rationale

Chorioamnionitis and antenatal glucocorticoids are common exposures for preterm infants and can affect the fetal brain, contributing to cognitive and motor deficits in preterm infants. The effects of antenatal glucocorticoids on the brain in the setting of chorioamnionitis are unknown. We hypothesized that antenatal glucocorticoids would modulate inflammation in the brain and prevent hippocampal and white matter injury after intra-amniotic lipopolysaccharide (LPS) exposure.

Methods

Time-mated ewes received saline (control), an intra-amniotic injection of 10 mg LPS at 106d GA or 113d GA, maternal intra-muscular betamethasone (0.5 mg/kg maternal weight) alone at 113d GA, betamethasone at 106d GA before LPS or betamethasone at 113d GA after LPS. Animals were delivered at 120d GA (term=150d). Brain structure volumes were measured on T2-weighted MRI images. The subcortical white matter (SCWM), periventricular white matter (PVWM) and hippocampus were analyzed for microglia, astrocytes, apoptosis, proliferation, myelin and pre-synaptic vesicles.

Results

LPS and/or betamethasone exposure at different time-points during gestation did not alter brain structure volumes on MRI. Betamethasone alone did not alter any of the measurements. Intra-amniotic LPS at 106d or 113d GA induced inflammation as indicated by increased microglial and astrocyte recruitment which was paralleled by increased apoptosis and hypomyelination in the SCWM and decreased synaptophysin density in the hippocampus. Betamethasone before the LPS exposure at 113d GA prevented microglial activation and the decrease in synaptophysin. Betamethasone after LPS exposure increased microglial infiltration and apoptosis.

Conclusion

Intra-uterine LPS exposure for 7d or 14d before delivery induced inflammation and injury in the fetal white matter and hippocampus. Antenatal glucocorticoids aggravated the inflammatory changes in the brain caused by pre-existing intra-amniotic inflammation. Antenatal glucocorticoids prior to LPS reduced the effects of intra-uterine inflammation on the brain. The timing of glucocorticoid administration in the setting of chorioamnionitis can alter outcomes for the fetal brain.

Preterm birth and adolescent social functioning-alterations in emotion-processing brain areas

OBJECTIVE

To investigate the relationship between preterm birth, adolescent, and adult psychosocial outcomes, and alterations in gray matter volume.

STUDY DESIGN

Individuals (n = 73) born at <33 weeks of gestation (very preterm) and 49 controls completed the Child Behavior Checklist (CBCL) at age 15 years to identify 'social immaturity' (SI) cases. Voxel-based morphometry was used to investigate gray matter volumes according to CBCL-SI 'caseness.' The Clinical Interview Schedule-Revised (CIS-R) was administered at age 19 years.

RESULTS

Very preterm adolescents were almost 4 times more likely to reach CBCL-SI 'caseness' compared with controls. Ex-preterm SI 'cases' had increased gray matter volume in the fusiform gyrus bilaterally (Talairach coordinates: x = 60, y = -27, z = -30; Z = 3.78; x = -61, y = -35, z = -27; Z = 3.56, after correction for multiple comparisons) compared with ex-preterm SI 'noncases.' Left fusiform volume displayed a stronger correlation with ipsilateral orbitofrontal cortex in SI 'cases' (x = -15, y = 22, z = -26; Z = 3.64). CIS-R total scores were slightly higher in ex-preterm individuals compared with controls. In the whole sample, SI 'cases' in midadolescence also had higher CIS-R scores in adulthood compared with 'noncases' (SI 'cases': mean = 5.7, 95% CI = 4.0-7.4; SI 'noncases': mean = 2.7, 95% CI = 1.1-4.3; F = 6.4, df = 74; P = .013).

CONCLUSIONS

Ex-preterm adolescents had increased socialization problems in adolescence, which were associated with volumetric alterations in an emotion-processing brain network. Atypical social development is linked to an increased vulnerability to psychiatric disorder.

Neuropathologic studies of the encephalopathy of prematurity in the late preterm infant

It has been widely suggested that brain damage in survivors of late preterm deliveries is similar to that in early preterm infants, only less severe. This report addresses this concept through reanalysis of published neuropathologic data obtained according to late preterm in comparison with early preterm ages. Findings suggest that the spectrum of brain injury in the late preterm infant, as determined in an autopsy population, is similar to that found in early preterm infants, with potential differential susceptibility for different neuronal, glial, and vascular indices. Further research is needed to more clearly define developmental cellular susceptibilities in preterm populations.

Autism and EMF? Plausibility of a pathophysiological link part II

Autism spectrum conditions (ASCs) are defined behaviorally, but they also involve multileveled disturbances of underlying biology that find striking parallels in the physiological impacts of electromagnetic frequency and radiofrequency radiation exposures (EMF/RFR). Part I (Vol 776) of this paper reviewed the critical contributions pathophysiology may make to the etiology, pathogenesis and ongoing generation of behaviors currently defined as being core features of ASCs. We reviewed pathophysiological damage to core cellular processes that are associated both with ASCs and with biological effects of EMF/RFR exposures that contribute to chronically disrupted homeostasis. Many studies of people with ASCs have identified oxidative stress and evidence of free radical damage, cellular stress proteins, and deficiencies of antioxidants such as glutathione. Elevated intracellular calcium in ASCs may be due to genetics or may be downstream of inflammation or environmental exposures. Cell membrane lipids may be peroxidized, mitochondria may be dysfunctional, and various kinds of immune system disturbances are common. Brain oxidative stress and inflammation as well as measures consistent with blood-brain barrier and brain perfusion compromise have been documented. Part II of this paper documents how behaviors in ASCs may emerge from alterations of electrophysiological oscillatory synchronization, how EMF/RFR could contribute to these by de-tuning the organism, and policy implications of these vulnerabilities. It details evidence for mitochondrial dysfunction, immune system dysregulation, neuroinflammation and brain blood flow alterations, altered electrophysiology, disruption of electromagnetic signaling, synchrony, and sensory processing, de-tuning of the brain and organism, with autistic behaviors as emergent properties emanating from this pathophysiology. Changes in brain and autonomic nervous system electrophysiological function and sensory processing predominate, seizures are common, and sleep disruption is close to universal. All of these phenomena also occur with EMF/RFR exposure that can add to system overload ('allostatic load') in ASCs by increasing risk, and can worsen challenging biological problems and symptoms; conversely, reducing exposure might ameliorate symptoms of ASCs by reducing obstruction of physiological repair. Various vital but vulnerable mechanisms such as calcium channels may be disrupted by environmental agents, various genes associated with autism or the interaction of both. With dramatic increases in reported ASCs that are coincident in time with the deployment of wireless technologies, we need aggressive investigation of potential ASC-EMF/RFR links. The evidence is sufficient to warrant new public exposure standards benchmarked to low-intensity (non-thermal) exposure levels now known to be biologically disruptive, and strong, interim precautionary practices are advocated.

Understanding neurodevelopmental outcomes of prematurity: education priorities for NICU parents

NICU nurses have an important role to play in many aspects of parent education. This article stresses the need for an increased focus on teaching parents about the central role that self-regulation will play in their infant's neurobehavioral development not only during the early infancy period but throughout all of childhood and adolescence. Suggestions are made about how to conceptualize the relation between cognition and emotions in humans and how to help parents understand that continued vigilance concerning potential problems in attention and self-regulation will be necessary.

Toward better recognition of early predictors for autism spectrum disorders

BACKGROUND

Identification and diagnosis of autism spectrum disorders is essentially based on behavioral presentation and developmental history. The current average age at diagnosis is older than 3 years.

METHODS

Over the past 15 years, there has been increasing documentation of the early signs of autism spectrum disorders through both individual retrospective parental reports and screening studies. Recent longitudinal studies have focused on early medical and behavioral features of children regarded at risk, namely younger siblings of children with autism spectrum disorders or children who required neonatal intensive care, with a later diagnosis of autism spectrum disorders.

RESULTS

Potentially useful early neurological signs and developmental predictors for autism spectrum disorders could be identified, with a typical profile that evolved with age.

CONCLUSIONS

Assessment of early social attention and communication skills with adapted scales in children before the age of 18 months in very large community-based settings may lead to high positive predictive values.

Higher prevalence of autism in Taiwanese children born prematurely: a nationwide population-based study

The reported prevalence of autism in preterm and full-term children varies partially because of small sample sizes. Moreover, little is known about the specific factors that contribute to the risk of autism in preterm children. We aimed to compare the prevalence of autism in preterm and full-term children and to identify neonatal risk factors for autism in preterm children using a large national health system database. We analyzed data from 1078 early preterm (<28 weeks of gestation or birth weight<1000 g), 28,947 later preterm (28-36 weeks), and 1,104,071 full-term (≥ 37 weeks) children who were 8-11 years old in 2009. The descending order of prevalence was early preterm (2.2%), later preterm (1.3%), and full-term (0.6%). The prevalence of autism was approximately 2-4 times higher in preterm children than in children born at full-term. The male-female ratio (4:1) in preterm and full-term children was not significantly different. Most of the children were first diagnosed with autism between 3 and 6 years old. Preterm children with autism were not diagnosed earlier than were full-term children. Regression analysis showed that male gender, a very low birth weight, and neonatal cerebral dysfunction were risk factors for autism in the preterm group. We conclude that autism is more prevalent in preterm children. Preventing extremely preterm birth and significant early brain insults may be helpful in reducing the risk of autism in preterm children.

Neuropsychological investigation of motor impairments in autism

It is unclear how standardized neuropsychological measures of motor function relate to brain volumes of motor regions in autism spectrum disorder (ASD). An all-male sample composed of 59 ASD and 30 controls (ages 5-33 years) completed three measures of motor function: strength of grip (SOG), finger tapping test (FTT), and grooved pegboard test (GPT). Likewise, all participants underwent magnetic resonance imaging with region of interest (ROI) volumes obtained to include the following regions: motor cortex (precentral gyrus), somatosensory cortex (postcentral gyrus), thalamus, basal ganglia, cerebellum, and caudal middle frontal gyrus. These traditional neuropsychological measures of motor function are assumed to differ in motor complexity, with GPT requiring the most followed by FTT and SOG. Performance by ASD participants on the GPT and FTT differed significantly from that of controls, with the largest effect size differences observed on the more complex GPT task. Differences on the SOG task between the two groups were nonsignificant. Since more complex motor tasks tap more complex networks, poorer GPT performance by those with ASD may reflect less efficient motor networks. There was no gross pathology observed in classic motor areas of the brain in ASD, as ROI volumes did not differ, but FTT was negatively related to motor cortex volume in ASD. The results suggest a hierarchical motor disruption in ASD, with difficulties evident only in more complex tasks as well as a potential anomalous size-function relation in motor cortex in ASD.

Children born prematurely have atypical sensory profiles

OBJECTIVE

To determine if children born prematurely exhibit atypical responses to normally occurring sensory stimuli, as measured by the Sensory Profile.

STUDY DESIGN

This is a cross-sectional study of children born at 32 weeks gestation, followed at 1 to 8 years of age. The Sensory Profile questionnaire was completed by each child's primary caregiver. The overall Sensory Profile was considered atypical if any quadrant or section score was >2 s.d. from the mean of the Sensory Profile validation group. Bivariate analyses were performed to determine associations between risk factors for adverse neurodevelopment and overall atypical Sensory Profiles. A section or quadrant was considered atypical if its score was >2 s.d. from the mean. A test of proportions was used to compute observed versus expected scores for each section and quadrant (Sensory Profile scores were based on a normal distribution so one would expect approximately 95% of participants to score within 2 s.d. of the mean).

RESULT

Of our 107 participants, 39% had an atypical score in at least one section or quadrant. No specific perinatal or neonatal risk factors were associated with atypical overall Sensory Profiles (P0.05 for all). Children born prematurely were at risk of having atypical scores in the auditory, tactile and vestibular processing sections, and in the four Sensory Profile quadrants (P<0.05).

CONCLUSION

Children born prematurely exhibit atypical sensory behaviors on the Sensory Profile. Further investigation to understand the underlying neural mechanisms and to develop effective interventions are critical to support neurodevelopment for these children.

Autism spectrum disorder in children born preterm-role of exposure to perinatal inflammation

Autism Spectrum Disorder (ASD) is the collective term for neurodevelopmental disorders characterized by qualitative impairments in social interaction, communication, and a restricted range of activities and interests. Many countries, including Australia, have reported a dramatic increase in the number of diagnoses over the past three decades, with current prevalence of ASD at 1 in every 110 individuals (~1%). The potential role for an immune-mediated mechanism in ASD has been implicated by several studies, and some evidence suggests a potential link between prenatal infection-driven inflammation and subsequent development of ASD. Furthermore, a modest number of contemporary studies have reported a markedly increased prevalence of ASD in children born preterm, who are at highest risk of exposure to perinatal inflammation. However, the mechanisms that underpin the susceptibility to infection-driven inflammation during pregnancy and risk of preterm birth, and how these intersect with the subsequent development of ASD in the offspring, is not understood. This review aims to summarize and discuss the potential mechanisms and evidence for the role of prenatal infection on the central nervous system, and how it may increase the susceptibility for ASD pathogenesis in children born preterm.

Autism spectrum disorder is associated with ventricular enlargement in a low birth weight population

OBJECTIVE

To determine the relation of neonatal cranial ultrasound abnormalities to autism spectrum disorders (ASD) in low birth weight (LBW) adult survivors, a population at increased ASD risk.

STUDY DESIGN

This is a secondary analysis of a prospectively-followed regional birth cohort of 1105 LBW infants systematically screened for perinatal brain injury with cranial ultrasound in the first week of life and later assessed for ASD using a two-stage process [screening at age 16 years (n = 623) followed by diagnostic assessment at age 21 years of a systematically selected subgroup of those screened (n = 189)]; 14 cases of ASD were identified. For this analysis, cranial ultrasound abnormalities were defined as ventricular enlargement (indicative of diffuse white matter injury), parenchymal lesions (indicative of focal white matter injury), and isolated germinal matrix/intraventricular hemorrhage.

RESULTS

Compared with no cranial ultrasound abnormalities, any type of white matter injury (ventricular enlargement and/or parenchymal lesion) tripled the risk for screening positively for ASD [3.0 (2.2, 4.1)]. However, the risk of being diagnosed with ASD depended on type of white matter injury. With ventricular enlargement, the risk of ASD diagnosis was almost seven-fold that of no cranial ultrasound abnormality [6.7 (2.3, 19.7)], and no elevated risk was found for parenchymal lesion without ventricular enlargement [1.8 (0.2, 13.6)]. Isolated germinal matrix/intraventricular hemorrhage did not increase risk for a positive ASD screen or diagnosis.

CONCLUSION

In LBW neonates, cranial ultrasound evidence of ventricular enlargement is a strong and significant risk factor for subsequent development of rigorously-diagnosed ASD.

The impact of chorioamnionitis on neurodevelopmental outcomes at 3, 8 and 18 years in low-birthweight preterm infants

OBJECTIVE

To assess the long-term cognitive, behavioral and academic status of preterm children exposed to clinical chorioamnionitis.

STUDY DESIGN

In total, 985 infants (<37 weeks and 2500 g at birth) were recruited in a multisite interventional research program. Of these, 43 case-infants were identified based on documented diagnosis of maternal clinical chorioamnionitis. Infants with chorioamnionitis were compared with the remainder of the cohort after controlling for maternal and infant variables. All infants underwent cognitive, behavioral and academic achievement assessments at 3, 8 and 18 years. Standardized cognitive and academic achievement scores were cutoff at 2 s.d.'s below the mean, behavioral scores were cutoff at a T-score >70 and examined with χ(2) statistics. Mean scores were evaluated using preliminary bivariate analysis and were followed by multiple regression models predicting child outcomes.

RESULT

Overall, children with chorioamnionitis did not have lower scores on any assessment at any age. Children without chorioamnionitis performed significantly lower at 8 years on the Woodcock-Johnson reading subscore and the mean score of the Peabody Picture Vocabulary Test (PPVT). No significant difference persisted to 18-year follow-up. In logistic regression, chorioamnionitis independently predicted higher PPVT scores at 8 years, but not lower performance scores on the Woodcock-Johnson reading subscore.

CONCLUSION

Clinical chorioamnionitis was not associated with adverse neurodevelopmental outcomes in this group of preterm infants <37 weeks and 2500 g.

Limitations on the developing preterm brain: impact of periventricular white matter lesions on brain connectivity and cognition

Brain lesions to the white matter in peritrigonal regions, periventricular leukomalacia, in children who were born prematurely represent an important model for studying limitations on brain development. The lesional pattern is of early origin and bilateral, that constrains the compensatory potential of the brain. We suggest that (i) topography and severity of periventricular lesions may have a long-term predictive value for cognitive and social capabilities in preterm birth survivors; and (ii) periventricular lesions may impact cognitive and social functions by affecting brain connectivity, and thereby, the dissociable neural networks underpinning these functions. A further pathway to explore is the relationship between cerebral palsy and cognitive outcome. Restrictions caused by motor disability may affect active exploration of surrounding and social participation that may in turn differentially impinge on cognitive development and social cognition. As an outline for future research, we underscore sex differences, as the sex of a preterm newborn may shape the mechanisms by which the developing brain is affected.

Localization of a major susceptibility locus influencing preterm birth

Preterm birth (PTB) is a complex trait, but little is known regarding its major genetic determinants. The objective of this study is to localize genes that influence susceptibility to PTB in Mexican Americans (MAs), a minority population in the USA, using predominantly microfilmed birth certificate-based data obtained from the San Antonio Family Birth Weight Study. Only 1302 singleton births from 288 families with information on PTB and significant covariates were considered for genetic analysis. PTB is defined as a childbirth that occurs at <37 completed weeks of gestation, and the prevalence of PTB in this sample was 6.4%. An ∼10 cM genetic map was used to conduct a genome-wide linkage analysis using the program SOLAR. The heritability of PTB was high (h(2) ± SE: 0.75 ± 0.20) and significant (P = 4.5 × 10(-5)), after adjusting for the significant effects of birthweight and birth order. We found significant evidence for linkage of PTB (LOD = 3.6; nominal P = 2.3 × 10(-5); empirical P = 1.0 × 10(-5)) on chromosome 18q between markers D18S1364 and D18S541. Several other chromosomal regions (2q, 9p, 16q and 20q) were also potentially linked with PTB. A strong positional candidate gene in the 18q linked region is SERPINB2 or PAI-2, a member of the plasminogen activator system that is associated with various reproductive processes. In conclusion, to our knowledge, perhaps for the first time in MAs or US populations, we have localized a major susceptibility locus for PTB on chromosome 18q21.33-q23.

The effect of gestational age on symptom severity in children with autism spectrum disorder

Between 2006 and 2010, two research-validated instruments, Social Communication Questionnaire (SCQ) and Social Responsiveness Scale (SRS) were filled out online by 4,188 mothers of Autism Spectrum Disorder (ASD) children, aged 4-21, as part of voluntary parental participation in a large web-based registry. Univariate and multivariate linear regression analysis (adjusted for child's sex, ability to verbalize, categorical IQ score, and fetal growth rate) demonstrated significantly higher SCQ and SRS scores for ASD children of both preterm (<37 weeks) and post-term (>42 weeks) gestational age (GA) compared to ASD children of normal GA, thus indicating that both preterm and post-term children manifest increased ASD symptomatology. Normal GA at birth appears to mitigate the severity of autistic social impairment in ASD children.

Behavioural outcomes and psychopathology during adolescence

Preterm birth is associated with a high risk of residual neurodevelopmental disability and cognitive impairment. These problems are closely associated with psychiatric disorders and thus it is unsurprising that preterm birth also confers high risk for poor long term mental health. The risk associated with preterm birth is not a general one, but appears to be specific to symptoms and disorders associated with anxiety, inattention and social and communication problems, and manifest in a significantly higher prevalence of emotional disorders, ADHD and Autism. Adolescence is a key period for mental health and studies have shown that problems evident in childhood persist over this time and are more stable amongst preterm individuals than term-born peers. There is also modest evidence for an increased prevalence of psychotic symptoms in preterm adolescents. The high prevalence of psychiatric disorders, present in around 25% of preterm adolescents, requires long term screening and intervention.

Preterm birth: neuropsychological profiles and atypical developmental pathways

Preterm birth is characterized by multiple interacting atypical constraints affecting different aspects of neuropsychological development. In the first years of life, perceptual, motor, and communicative-linguistic abilities, as well as attention, processing speed, and memory are affected by preterm birth resulting in cascading effects on later development. From school age to adolescence, a catch-up of simpler competencies (i.e., receptive lexicon) along with a more selective effect on more complex competencies (i.e., complex linguistic functions, math, motor, and executive functions) are observed, as well as a relevant incidence of behavioral outcomes. A wide heterogeneity in preterm children's neuropsychological profiles is described depending on the interaction among the degree of neonatal immaturity, medical complications, neurological damages/alterations, environmental and social factors. Severe neuromotor and sensory damages are not frequent, while low severity impairments are common among preterm children. It is argued that developmental pathways of preterm children are atypical, and not merely delayed, and are characterized by different developmental patterns and relationships among competencies.

The consequences of chorioamnionitis: preterm birth and effects on development

Preterm birth is a major cause of perinatal mortality and long-term morbidity. Chorioamnionitis is a common cause of preterm birth. Clinical chorioamnionitis, characterised by maternal fever, leukocytosis, tachycardia, uterine tenderness, and preterm rupture of membranes, is less common than subclinical/histologic chorioamnionitis, which is asymptomatic and defined by inflammation of the chorion, amnion, and placenta. Chorioamnionitis is often associated with a fetal inflammatory response. The fetal inflammatory response syndrome (FIRS) is defined by increased systemic inflammatory cytokine concentrations, funisitis, and fetal vasculitis. Clinical and epidemiological studies have demonstrated that FIRS leads to poor cardiorespiratory, neurological, and renal outcomes. These observations are further supported by experimental studies that have improved our understanding of the mechanisms responsible for these outcomes. This paper outlines clinical and experimental studies that have improved our current understanding of the mechanisms responsible for chorioamnionitis-induced preterm birth and explores the cellular and physiological mechanisms underlying poor cardiorespiratory, neural, retinal, and renal outcomes observed in preterm infants exposed to chorioamnionitis.

Genome-wide analysis of DNA methylation in human amnion

The amnion is a specialized tissue in contact with the amniotic fluid, which is in a constantly changing state. To investigate the importance of epigenetic events in this tissue in the physiology and pathophysiology of pregnancy, we performed genome-wide DNA methylation profiling of human amnion from term (with and without labor) and preterm deliveries. Using the Illumina Infinium HumanMethylation27 BeadChip, we identified genes exhibiting differential methylation associated with normal labor and preterm birth. Functional analysis of the differentially methylated genes revealed biologically relevant enriched gene sets. Bisulfite sequencing analysis of the promoter region of the oxytocin receptor (OXTR) gene detected two CpG dinucleotides showing significant methylation differences among the three groups of samples. Hypermethylation of the CpG island of the solute carrier family 30 member 3 (SLC30A3) gene in preterm amnion was confirmed by methylation-specific PCR. This work provides preliminary evidence that DNA methylation changes in the amnion may be at least partially involved in the physiological process of labor and the etiology of preterm birth and suggests that DNA methylation profiles, in combination with other biological data, may provide valuable insight into the mechanisms underlying normal and pathological pregnancies.

Gestational age at birth and risk of autism spectrum disorders in Alberta, Canada

OBJECTIVE

To examine the association between autism spectrum disorders (ASD) and each completed week of gestation using a graphical method of presenting results at all possible categorizations of gestational age (GA).

STUDY DESIGN

The risk of ASD in a total of 218110 singleton live births with complete data from Alberta, Canada between 1998 and 2004 was examined through linkage to health insurance records. The relative risk of developing ASD according to the 21 dichotomizations of shorter gestation (GA ≤ 23 weeks vs >23 weeks to ≤ 43 weeks vs >43 weeks, in 1-week increments) was calculated using log-binomial regression and adjusted for fetal sex, socioeconomic status, and birth year.

RESULTS

We observed a gradual increased risk of ASD with shorter gestation. Cutoffs only between 29 and 40 weeks clearly denoted an elevated risk of developing ASD compared with longer gestation, and the risk increased with earlier GA cutoff. The results were not affected by sex or measures of fetal growth.

CONCLUSION

Our data confirm the role of shortened gestation in ASD risk. We warn against the use of prespecified or a data-driven GA cutoff, however; instead, we recommend systematically examining all plausible cutoffs for GA to avoid overstating the homogeneity of risk in children on either side of a given cutoff, as well as to increase the comparability of studies.

Maternal conditions and perinatal characteristics associated with autism spectrum disorder and intellectual disability

Background

As well as being highly comorbid conditions, autism spectrum disorders (ASD) and intellectual disability (ID) share a number of clinically-relevant phenomena. This raises questions about similarities and overlap in diagnosis and aetiological pathways that may exist for both conditions.

Aims

To examine maternal conditions and perinatal factors for children diagnosed with an ASD, with or without ID, and children with ID of unknown cause, compared with unaffected children.

Methods

The study population comprised all live singleton births in Western Australia (WA) between January 1984 and December 1999 (N = 383,153). Univariate and multivariate multinomial logistic regression models were applied using a blocked modelling approach to assess the effect of maternal conditions, sociodemographic factors, labour and delivery characteristics and neonatal outcomes.

Results

In univariate analyses mild-moderate ID was associated with pregnancy hypertension, asthma, urinary tract infection, some types of ante-partum haemorrhage, any type of preterm birth, elective C-sections, breech presentation, poor fetal growth and need for resuscitation at birth, with all factors showing an increased risk. Severe ID was positively associated with poor fetal growth and need for resuscitation, as well as any labour or delivery complication. In the multivariate analysis no maternal conditions or perinatal factors were associated with an increased risk of ASD without ID. However, pregnancy hypertension and small head circumference were associated with a reduced risk (OR = 0.64, 95% CI: 0.43, 0.94; OR = 0.58, 95% CI: 0.34, 0.96, respectively). For ASD with ID, threatened abortion before 20 weeks gestation and poor fetal growth were associated with an increased risk.

Conclusion

Findings show that indicators of a poor intrauterine environment are associated with an elevated risk of ID, while for ASD, and particularly ASD without ID, the associations are much weaker. As such, these findings highlight the importance of accounting for the absence or presence of ID when examining ASD, if we are to improve our understanding of the causal pathways associated with these conditions.

Autism spectrum disorder and the cerebellum

The cerebellum has been long known for its importance in motor learning and coordination. Recently, anatomical, clinical, and neuroimaging studies strongly suggest that the cerebellum supports cognitive functions, including language and executive functions, as well as affective regulation. Furthermore, the cerebellum has emerged as one of the key brain regions affected in autism. Here, we discuss our current understanding of the role of the cerebellum in autism, including evidence from genetic, molecular, clinical, behavioral, and neuroimaging studies. Cerebellar findings in autism suggest developmental differences at multiple levels of neural structure and function, indicating that the cerebellum is an important player in the complex neural underpinnings of autism spectrum disorder, with behavioral implications beyond the motor domain.

TLR-4-dependent and -independent mechanisms of fetal brain injury in the setting of preterm birth

In this study, we sought to assess how essential activation of toll-like receptor 4 (TLR-4) is to fetal brain injury from intrauterine inflammation. Both wild-type and TLR-4 mutant fetal central nervous system cells were exposed to inflammation using lipopolysaccharide in vivo or in vitro. Inflammation could not induce neuronal injury in the absence of glial cells, in either wild-type or TLR-4 mutant neurons. However, injured neurons could induce injury in other neurons regardless of TLR-4 competency. Our results indicate that initiation of neuronal injury is a TLR-4-dependent event, while propagation is a TLR-4-independent event.

White matter injury following fetal inflammatory response syndrome induced by chorioamnionitis and fetal sepsis: lessons from experimental ovine models

Chorioamnionitis and fetal sepsis can induce a fetal inflammatory response syndrome (FIRS) which is closely related to the development of white matter injury in the fetal brain. Large epidemiological studies support the link between FIRS and fetal brain injury with a clear association between the presence of in utero inflammation and neurodevelopmental complications such as cerebral palsy, autism and cognitive impairments later in life. Translational animal models of chorioamnionitis and fetal sepsis are essential in understanding the underlying pathophysiological mechanisms of fetal brain injury after exposure to intra-uterine inflammation. Concerning this aspect, ovine models have high translational value since neurodevelopment in sheep closely resembles the human situation. In this article, we will review clinical and experimental evidence for the link between FIRS and white matter injury in the fetal brain. With respect to experimental findings, we will particularly focus on the lessons learned from ovine models of chorioamnionitis and fetal sepsis. We also highlight two key players implied in the pathophysiology of white matter injury after in utero exposure to inflammation.

Injury to the premature cerebellum: outcome is related to remote cortical development

Cerebellar injury is an important complication of preterm birth with far-reaching neuropsychiatric sequelae. We have previously shown a significant association between isolated injury to the premature cerebellum and subsequent impairment of regional volumetric growth in the contralateral cerebrum. In the current study, we examine the relationship between these remote regional impairments of cerebral volumetric growth and domain-specific functional deficits in these children. In 40 ex-preterm infants with isolated cerebellar injury, we performed neurodevelopmental evaluations and quantitative magnetic resonance imaging (MRI) studies at a mean age of 34 months. We measured cortical gray matter volumes in 8 parcellated regions of each cerebral hemisphere, as well as right and left cerebellar volumes. We show highly significant associations between early signs of autism and dorsolateral prefrontal cortex volume (P < 0.001); gross motor scores and sensorimotor cortical volumes (P < 0.001); and cognitive and expressive language scores and premotor and mid-temporal cortical volumes (P < 0.001). By multivariate analyses, each unit increase in the corresponding regional cerebral volume was associated with lower odds of abnormal outcome score, adjusted for age at MRI and contralateral cerebellar volume. This is the first report linking secondary impairment of remote cerebral cortical growth and functional disabilities in survivors of prematurity-related cerebellar brain injury.

An overview of risk factors for poor neurodevelopmental outcome associated with prematurity

BACKGROUND

Preterm birth is a major cause of neonatal mortality and morbidity. While advances in medical care have improved the survival of preterm infants, neurodevelopmental problems persist in this population. This article aims to review factors associated with their neurodevelopmental outcomes.

DATA SOURCES

English language studies of neurodevelopmental outcomes in preterm infants were retrieved from PubMed. A total of 100 related publications were included.

RESULTS

Early gestational age and birth weight are the most significant predictors of poor long-term neurological outcome. Structural changes of the brain, infection, male gender and neonatal intensive care unit course are also important factors affecting eventual outcome. Other complex biological and socio-economic factors, which extend from prenatal through postnatal periods, up through and including adulthood, also affect the trajectory of brain development in preterm infants.

CONCLUSIONS

Neurodevelopmental problems continue to affect the preterm population. There is a critical need for collaboration among geneticists, obstetricians, pediatricians, and neuroimaging and rehabilitation experts to determine early predictive factors and neuroprotective therapies to properly treat or prevent poor neurodevelopmental outcomes in these infants.

Placental regulation of maternal-fetal interactions and brain development

A variety prenatal insults are associated with the incidence of neurodevelopmental disorders such as schizophrenia, autism and cerebral palsy. While the precise mechanisms underlying how transient gestational challenges can lead to later life dysfunctions are largely unknown, the placenta is likely to play a key role. The literal interface between maternal and fetal cells resides in the placenta, and disruptions to the maternal or intrauterine environment are necessarily conveyed to the developing embryo via the placenta. Placental cells bear the responsibility of promoting maternal tolerance of the semiallogeneic fetus and regulating selective permeability of nutrients, gases, and antibodies, while still providing physiological protection of the embryo from adversity. The placenta's critical role in modulating immune protection and the availability of nutrients and endocrine factors to the offspring implicates its involvement in autoimmunity, growth restriction and hypoxia, all factors associated with the development of neurological complications. In this review, we summarize primary maternal-fetal interactions that occur in the placenta and describe pathways by which maternal insults can impair these processes and disrupt fetal brain development. We also review emerging evidence for placental dysfunction in the prenatal programming of neurodevelopmental disorders.