Preterm Individuals Research Articles

Preterm Birth and Adolescent Bone Mineral Content

The purpose of this study was to determine the influence of preterm low birth weight on bone mineral content in adolescence. In 2007 to 2008, data on adolescents were obtained for study, including 16 females and 25 males who were born preterm (≤37 weeks' gestation) between October 1, 1989, and December 31, 1995, with a birth weight of less than 1850 g. Preterm low-birth-weight individuals were age- and sex-matched to full-term (>37 weeks) normal-birth-weight (>2500 g) controls. Total body, hip, and spine bone mineral content (BMC) was assessed using dual energy X-ray absorptiometry. Male preterm individuals had less BMC at the proximal femur in adolescence compared with controls ( p < 0.05). However, once adjusted for age, maturity, height, weight, physical activity, and diet, there were no differences between groups ( p < 0.05) in any bone parameters. These findings suggest that preterm birth and low birth weight did not influence bone accrual in these individuals at adolescence.

Structural Correlates of Preterm Birth in the Adolescent Brain

The Stockholm Neonatal Project involves a prospective, cross-sectional, population-based, cohort monitored for 12 to 17 years after birth; it was started with the aim of investigating the long-term structural correlates of preterm birth and comparing findings with reports on similar cohorts. High-resolution anatomic and diffusion tensor imaging data measuring diffusion in 30 directions were collected by using a 1.5-T MRI scanner. A total of 143 adolescents (12.18-17.7 years of age) participated in the study, including 74 formerly preterm infants with birth weights of <or=1500 g (range: 645-1486 g) and 69 term control subjects. The 2 groups were well matched with respect to demographic and socioeconomic data. The anatomic MRI data were used for calculation of total brain volumes and voxelwise comparison of gray matter (GM) volumes. The diffusion tensor imaging data were used for voxelwise comparison of white matter (WM) microstructural integrity. The formerly preterm individuals possessed 8.8% smaller GM volume and 9.4% smaller WM volume. The GM and WM volumes of individuals depended on gestational age and birth weight. The reduction in GM could be attributed bilaterally to the temporal lobes, central, prefrontal, orbitofrontal, and parietal cortices, caudate nuclei, hippocampi, and thalami. Lower fractional anisotropy was observed in the posterior corpus callosum, fornix, and external capsules. Although preterm birth was found to be a risk factor regarding long-term structural brain development, the outcome was milder than in previous reports. This may be attributable to differences in social structure and neonatal care practices.

Very Preterm Birth, Cerebellar Development and Neuropsychological Outcome in Adolescence

Cerebellar volumes were measured on structural MRI at adolescence and adulthood in 65 preterm individuals (born before 33 weeks’ gestation), and a term-born comparison group, in a study at King’s College, Great Ormond Street Hospital, and University College, London; and Seoul National University College of Medicine, Korea.

Cognitive maturation in preterm and term born adolescents

Background:Adolescence is a critical period of brain structural reorganisation and maturation of cognitive abilities. This relatively late developmental reorganisation may be altered in individuals who were born preterm.Methods:We carried out...

Vermis and lateral lobes of the cerebellum in adolescents born very preterm

Adolescents born before 33 weeks' gestation have reduced cerebellar volume compared with term-born controls, and this is related to their cognitive performance. We wished to determine whether this relationship is regionally specific. We measured midline and lateral cerebellar volumes in magnetic resonance imaging scans from 67 very preterm adolescents and 50 term-born controls at 14-15 years. Volumes of vermis and lateral lobes were reduced in the preterm group, after controlling for whole-brain volume. Lateral cerebellar volume decrease was associated with reduced cerebral white matter volume, and with reduced executive, visuo-spatial and language function. Vermis volume was less strongly related to cognitive function. Volume decrement of the lateral lobes, rather than the vermis, is associated with neuropsychological dysfunction in very preterm individuals.

Hyperactivity in adolescents born very preterm is associated with decreased caudate volume

Several studies have associated preterm birth with impaired behavioral functioning and attention problems. In addition, preterm individuals have an increased risk of brain injury in the neonatal period. Such early lesions have the potential to disrupt subsequent neurodevelopment. This study explored behavioral functioning, particularly externalizing behavior, in a group of adolescents who were born very preterm and its relationship with volume of the caudate, a brain region particularly vulnerable to damage in the preterm neonate. We studied 72 adolescents born before 33 weeks and 50 age- and gender-matched full-term control subjects. Behavioral assessment included the Rutter Behavioural Scale and a social adjustment scale. Bilateral caudate volumes were quantified by stereologic methods. Preterm adolescents scored significantly higher than control subjects on the Rutter hyperactivity score, and boys scored higher than girls. In preterm boys only, left caudate volume was negatively correlated with hyperactivity score (r = -.43, p = .018) and social adjustment score in childhood (r = -.40, p = .028). Our data suggest that boys born very preterm are more likely to experience nonclinical behavioral problems in adolescence compared with full-term control subjects. Our results indicate that behavioral problems in this group might be associated with reductions in volume of the left caudate nucleus.

Corpus Callosum Size and Verbal Intelligence

Quantitative MRI measurements of the sagittal surface area of the corpus callosum (CC) in 72 preterm individuals tested at adolescence (14-15 years) were compared with verbal skills on neuropsychological tests in a study at the Institute of Psychiatry, De Crespigny Park, London, UK.

Corpus callosum size and very preterm birth: relationship to neuropsychological outcome.

Thinning of the corpus callosum (CC) is often observed in individuals who were born very preterm. Damage to the CC during neurodevelopment may be associated with poor neuropsychological performance. This study aimed to explore any evidence of CC pathology in adolescents aged 14-15 years who were born very preterm, and to investigate the relationship between CC areas and verbal skills. Seventy-two individuals born before 33 weeks of gestation and 51 age- and sex-matched full-term controls received structural MRI and neuropsychological assessment. Total CC area in very preterm adolescents was 7.5% smaller than in controls, after adjusting for total white matter volume (P = 0.015). The absolute size of callosal subregions differed between preterm and full-term adolescents: preterm individuals had a 14.7% decrease in posterior (P < 0.0001) and an 11.6% decrease in mid-posterior CC quarters (P = 0.029). Preterm individuals who had experienced periventricular haemorrhage and ventricular dilatation in the neonatal period showed the greatest decrease in CC area. In very preterm boys only, verbal IQ and verbal fluency scores were positively associated with total mid-sagittal CC size and mid-posterior surface area. These results suggest that very preterm birth adversely affects the development of the CC, particularly its posterior quarter, and this impairs verbal skills in boys.

Motor, cognitive, and behavioural disorders in children born very preterm

Children born preterm have been shown to exhibit poor motor function and behaviour that is associated with school failure in the presence of average intelligence. A geographically determined cohort of two‐hundred and eighty preterm children (151 males, 129 females) born before 32 weeks’gestation and attending mainstream schools were examined at 7 to 8 years of age together with 210 (112 males, 98 females) age‐ and sex‐matched control participants were tested for motor, cognitive, and behavioural problems. Tests applied were the Movement Assessment Battery for Children (MABC), Clinical Observations of Motor and Postural Skills (COMPS), Developmental Test of Visual‐Motor Integration (VMI), Wechsler Intelligence Scale for Children, and Connors’Teacher Rating Scale for attention‐deficit‐hyper‐activity disorder (ADHD). Control children scored significantly better than the preterm group on all motor, cognitive, and behavioural measures. The lowest birthweight and most preterm individuals tended to score the lowest. Motor impairment was diagnosed in 86 (30.7%) of the preterm group and 14 (6.7%) of the control children using the MABC; 97 (42.7%) and 18 (10.2%) using the COMPS; and 68 (24.3%) and 17 (8.1%) respectively using the VMI. Each test of motor function identified different children with disability, although 23 preterm children were identified as having motor disability by all three tests. Preterm children were more likely to have signs of inattention and impulsivity and have a diagnosis of ADHD. Minor motor disabilities persist in survivors of preterm birth despite improvements in care and are not confined to the smallest or most preterm infants. They may exist independently of cognitive and behavioural deficits, although they often co‐exist. The condition is heterogeneous and may require more than one test to identify all children with potential learning problems.

Motor, cognitive, and behavioural disorders in children born very preterm

Children born preterm have been shown to exhibit poor motor function and behaviour that is associated with school failure in the presence of average intelligence. A geographically determined cohort of two-hundred and eighty preterm children (151 males, 129 females) born before 32 weeks' gestation and attending mainstream schools were examined at 7 to 8 years of age together with 210 (112 males, 98 females) age- and sex-matched control participants were tested for motor, cognitive, and behavioural problems. Tests applied were the Movement Assessment Battery for Children (MABC), Clinical Observations of Motor and Postural Skills (COMPS), Developmental Test of Visual-Motor Integration (VMI), Wechsler Intelligence Scale for Children, and Connors' Teacher Rating Scale for attention-deficit-hyperactivity disorder (ADHD). Control children scored significantly better than the preterm group on all motor, cognitive, and behavioural measures. The lowest birthweight and most preterm individuals tended to score the lowest. Motor impairment was diagnosed in 86 (30.7%) of the preterm group and 14 (6.7%) of the control children using the MABC; 97 (42.7%) and 18 (10.2%) using the COMPS; and 68 (24.3%) and 17 (8.1%) respectively using the VMI. Each test of motor function identified different children with disability, although 23 preterm children were identified as having motor disability by all three tests. Preterm children were more likely to have signs of inattention and impulsivity and have a diagnosis of ADHD. Minor motor disabilities persist in survivors of preterm birth despite improvements in care and are not confined to the smallest or most preterm infants. They may exist independently of cognitive and behavioural deficits, although they often co-exist. The condition is heterogeneous and may require more than one test to identify all children with potential learning problems.

Bone mineralization in preterm infants.

In preterm neonates a large skeletal mineral deficit builds up between birth and 40 wk postconception. During the phase of catch-up growth between 40 and 60 wk postconception there is a catch-up in peripheral skeletal mineralization, so that by the age of 1 y the skeletal mineral content is similar in preterm and term infants, despite the former being smaller, a finding that has been replicated for lumbar spinal mineralization. Later follow-up studies suggest that this catch-up persists and mineralization remains appropriate for body size. However, given the continuing abnormal growth experience of former preterm individuals, it would still be important to examine their bone mineralization in early adulthood. A number of interventions can improve perinatal bone mineralization, but few studies examine their long-term effectiveness. One such study has suggested that a relatively poor mineral diet in this period is, counterintuitively, associated with a later advantage in skeletal mineralization. If this finding is repeatable, then it could result in a major change in nutrition strategy in the neonatal period.

AMINO ACIDS DO NOT SUPPRESS PROTEOLYSIS IN PRETERM NEONATES. • 1413

We have recently demonstrated dose dependent suppression of proteolysis with graded amino acid (aa) infusion in healthy term neonates (Am J Physiol, 1997). Rates of proteolysis are higher in preterm individuals, perhaps related to a greater need for aa supply for tissue remodeling and rapid growth. We hypothesized that preterm neonates would be resistant to suppression of proteolysis in response to aa infusion. To assess this, we measured the endogenous rates of appearance (Ra) of the essential aa's leucine (LEU) and phenylalanine (PHE) (reflecting proteolysis), LEU oxidation (LEU OX) and phenylalanine hydroxylation (PHE OH) (reflecting irreversible losses), and utilization of LEU and PHE for protein synthesis (PS) in 7 clinically stable preterm infants (32±0.5 wks gestation, 1.5±0.1 kg birth wt, 1.4±0.1 kg study wt, 6±1 days of age) during a basal glucose infusion (6mg/kg/min) and in response to a graded infusion of aa's (Aminosyn PF-1.2 & 2.5gm/kg/day).