Inter- and intra-modal matching in very low birth weight and small for gestational age adolescents

Thyroid hormone analogues: Promising therapeutic avenues to improve the neurodevelopmental outcomes of intrauterine growth restriction

Intrauterine growth restriction (IUGR) is a pregnancy complication impairing fetal growth and development. The compromised development is often attributed to disruptions of oxygen and nutrient supply from the placenta, resulting in a number of unfavourable physiological outcomes with impaired brain and organ growth. IUGR is associated with compromised development of both grey and white matter, predisposing the infant to adverse neurodevelopmental outcomes, including long-lasting cognitive and motor difficulties. Cerebral thyroid hormone (TH) signalling, which plays a crucial role in regulating white and grey matter development, is dysregulated in IUGR, potentially contributing to the neurodevelopmental delays associated with this condition. Notably, one of the major TH transporters, monocarboxylate transporter-8 (MCT8), is deficient in the fetal IUGR brain. Currently, no effective treatment to prevent or reverse IUGR exists. Management strategies involve close antenatal monitoring, management of maternal risk factors if present and early delivery if IUGR is found to be severe or worsening in utero. The overall goal is to determine the most appropriate time for delivery, balancing the risks of preterm birth with further fetal compromise due to IUGR. Drug candidates have shown either adverse effects or little to no benefits in this vulnerable population, urging further preclinical and clinical investigation to establish effective therapies. In this review, we discuss the major neuropathology of IUGR driven by uteroplacental insufficiency and the concomitant long-term neurobehavioural impairments in individuals born IUGR. Importantly, we review the existing clinical and preclinical literature on cerebral TH signalling deficits, particularly the impaired expression of MCT8 and their correlation with IUGR. Lastly, we discuss the current evidence on MCT8-independent TH analogues which mimic the brain actions of THs by being metabolised in a similar manner as promising, albeit underappreciated approaches to promote grey and white matter development and improve the neurobehavioural outcomes following IUGR.

Multidisciplinary and neuroimaging findings in preterm born very low birthweight individuals from birth to 28 years of age: A systematic review of a Norwegian prospective cohort study

BACKGROUND

Children born preterm with very low birthweight (VLBW) face long-lasting neurodevelopmental challenges, where multidisciplinary assessments are warranted. The International Classification of Functioning, Disability and Health (ICF) provides a framework for understanding and conceptualising these outcomes.

OBJECTIVES

We aimed to review clinical and neuroimaging findings from birth to adulthood in a Norwegian cohort of individuals born preterm with VLBW (gestational age <37 weeks, birthweight ≤1500 g) within the framework of ICF.

DATA SOURCES

We searched PubMed and Embase for articles reporting results of the Norwegian University of Science and Technology (NTNU) Low Birth Weight in a Lifetime Perspective study.

STUDY SELECTION AND DATA EXTRACTION

We included original articles reporting proportions of adverse outcomes, mean group differences, risk factors or associations between outcomes. Data were extracted according to ICF's two-level classification. Body functions and structures comprised outcomes of brain structures, cognition, mental health, vision, pain and physical health. Activities and participation comprised motor skills, general and social functioning, education, employment, and health-related quality of life.

SYNTHESIS

We performed a qualitative synthesis of included articles. Where mean (SD) was reported, we calculated group differences in SD units.

RESULTS

Fifty-eight publications were included. Within body functions and structures, increased prevalence of brain structure pathology, lower cognitive performance, mental health problems, visual and physical health impairments through childhood, adolescence and young adulthood were reported among preterm VLBW participants compared with controls. Within activities and participation, motor problems, lower general and social functioning, and lower academic attainment were found. Perinatal factors were associated with several outcomes, and longitudinal findings suggested persistent consequences of being born preterm with VLBW.

CONCLUSIONS

Being born preterm with VLBW has long-term influences on body functions and structures, activities and participation. The ICF is appropriate for assessing general domains of functioning and guiding the management of individuals born preterm with VLBW.

Sensory processing difficulties in school-age children born very preterm: An exploratory study

BACKGROUND

Very preterm birth has a detrimental impact on the developing brain, including widespread white matter brain abnormalities that threaten efficient sensory processing. Yet, sensory processing difficulties in very preterm children are scarcely studied, especially at school age.

AIMS

To investigate somatosensory registration, multisensory integration and sensory modulation.

PARTICIPANTS

57 very preterm school-age children (mean age=9.2years) were compared to 56 gender and age matched full-term children.

METHODS

Group differences on somatosensory registration tasks (Registration of Light Touch, Sensory Discrimination of Touch, Position Sense, Graphestesia), a computerized multisensory integration task, and the parent-reported Sensory Profile were investigated using t-tests and Mann-Whitney U tests.

RESULTS

In comparison to full-term children, very preterm children are less accurate on somatosensory registration tasks, including Registration of Light Touch (d=0.34), Position Sense (d=0.31) and Graphestesia (d=0.42) and show more sensory modulation difficulties (d=0.41), including both behavioral hyporesponsivity (d=0.52) and hyperresponsivity (d=0.56) to sensory stimuli. Tactile discrimination and multisensory integration efficiency were not affected in very preterm children. Aspects of sensory processing were only modestly related.

CONCLUSION

Very preterm children show sensory processing difficulties regarding somatosensory registration and sensory modulation, and preserved multisensory (audio-visual) integration. Follow-up care for very preterm children should involve screening of sensory processing difficulties at least up to school age.

Effects of induced placental and fetal growth restriction, size at birth and early neonatal growth on behavioural and brain structural lateralization in sheep

Poor perinatal growth in humans results in asymmetrical grey matter loss in fetuses and infants and increased functional and behavioural asymmetry, but specific contributions of pre- and postnatal growth are unclear. We therefore compared strength and direction of lateralization in obstacle avoidance and maze exit preference tasks in offspring of placentally restricted (PR: 10M, 13F) and control (CON: 23M, 17F) sheep pregnancies at 18 and 40 weeks of age, and examined gross brain structure of the prefrontal cortex at 52 weeks of age (PR: 14M, 18F; CON: 23M, 25F). PR did not affect lateralization direction, but 40-week-old PR females had greater lateralization strength than CON (P = .021). Behavioural lateralization measures were not correlated with perinatal growth. PR did not alter brain morphology. In males, cross-sectional areas of the prefrontal cortex and left hemisphere correlated positively with skull width at birth, and white matter area correlated positively with neonatal growth rate of the skull (all P < .05). These studies reinforce the need to include progeny of both sexes in future studies of neurodevelopmental programming, and suggest that restricting in utero growth has relatively mild effects on gross brain structural or behavioural lateralization in sheep.

Being born small for gestational age reduces white matter integrity in adulthood: a prospective cohort study

BACKGROUND

Being born small for gestational age (SGA) (birth weight <10th percentile) is connected to decreased white matter (WM) integrity in newborns and increased prevalence of psychiatric symptoms in adulthood. The aims of this study were to investigate whether being born SGA at term affects WM integrity in young adulthood and to explore possible relationships between fractional anisotropy (FA) and pre- and perinatal factors and cognitive and psychiatric outcomes in adulthood in SGA and controls.

METHODS

Diffusion tensor imaging and tract-based spatial statistics were conducted to test for voxelwise differences in FA in SGAs (n = 46) and controls (n = 57) at 18-22 y.

RESULTS

As compared with controls SGAs had reduced FA in ventral association tracts and internal/external capsules. In the SGAs, no relationship was found between FA and intrauterine head growth in the third trimester, although total intelligence quotient was negatively correlated to FA. In controls, a positive correlation was found between FA and brain growth in the third trimester and maternal smoking. No relationship was found between FA and psychiatric measures in SGAs or controls.

CONCLUSION

These results demonstrate that being born SGA leads to reduced WM integrity in adulthood, and suggest that different factors modulate the development of WM in SGA and control groups.

Neurodevelopmental delay in small babies at term: a systematic review

OBJECTIVE

Being small for gestational age (SGA) or having fetal growth restriction (FGR) may be associated with poorer neurodevelopmental outcomes compared to being appropriate for gestational age (AGA). The aim of this paper was to evaluate the existence and magnitude of decrease in neurodevelopmental scores in SGA and FGR infants born at term from a systematic review of the existing literature.

METHODS

Studies of neurodevelopment in SGA/FGR babies were identified from a search of the internet scientific databases. Studies that included preterm births and those that did not define absolute indices of standardized cognitive outcome were excluded. SGA was defined as birth weight below the 10(th) centile for gestation and FGR as the same birth-weight standard with abnormal umbilical artery Doppler ultrasound or evidence of abnormal placentation on pathology specimen studies. Effect size was calculated as the standardized mean difference between neurodevelopment scores of controls and SGA/FGR children.

RESULTS

There were 28 studies of SGA, with a total of 7861 SGA and 91 619 control AGA babies, and three studies of FGR, with a total of 119 FGR and 49 control AGA babies. Data synthesis showed that standardized neurodevelopmental scores in SGA babies were 0.32 SD (95% CI, 0.25-0.38) below those for normal controls, though with heterogeneity between studies (I(2) = 68.3%). Insufficient data were available for FGR babies.

CONCLUSION

The findings of the study demonstrate that among babies born at term, being SGA is associated with lower scores on neurodevelopmental outcomes compared to AGA controls. A trial designed to evaluate the effects of intervention in small fetuses born at term in order to improve the neurodevelopmental outcome is urgently needed.

Do visual impairments affect risk of motor problems in preterm and term low birth weight adolescents?

BACKGROUND

Increased prevalence of motor and visual problems has been reported in low birth weight populations, but the association between them is less studied.

AIM

To examine how visual impairments may be associated with the increased risk of motor problems in low birth weight adolescents.

METHODS

Fifty-one very low birth weight adolescents (VLBW), 56 term small for gestational age (SGA) and 75 term control adolescents, without cerebral palsy, were examined at the age of 14. Motor skills were examined by the Movement Assessment Battery for Children. Visual functions included visual acuity, contrast sensitivity, nystagmus, strabismus, stereoacuity, accommodation, convergence and visual perception (Visual-Motor Integration test). An abnormality score was calculated as the sum of visual impairments. We used odds ratio as an estimate of the relative risk of having motor problems.

RESULTS

The odds of having motor problems were 10.4 (95% CI: 2.2-49.4) in the VLBW group and 5.1 (95% CI: 1.0-25.8) in the SGA group compared with the control group. The odds of having motor problems in the VLBW group were influenced by all visual variables, and most by visual acuity, when we adjusted for these separately. The greatest reduction in OR was found when adjusting for the abnormality score (adjusted OR: 6.8; 95% CI: 1.3-34.5). In the SGA group the odds of having motor problems were relatively unaffected by the visual variables and the abnormality score.

CONCLUSIONS

Visual impairments influence motor problems in VLBW adolescents, whereas motor problems in SGA adolescents seem to be unaffected by visual impairments.