Short adult stature and overweight are associated with poor intellectual performance in subjects born preterm

Long-Term Neurodevelopmental Outcomes after Moderate and Late Preterm Birth: A Systematic Review

OBJECTIVE

To systematically review and perform meta-analyses on the long-term neurodevelopmental outcomes of adults born moderate and late preterm (MLPT) in relation to cognitive functioning and psychiatric disorders.

STUDY DESIGN

A search was conducted to identify any studies that involved prematurity in adulthood. From these studies, reports that included a group of MLPT adults and included description of cognitive and/or mental health domains (including specific long-term outcomes) were selected.

RESULTS

In total, 155 publications were identified, but only 16 papers met the inclusion criteria. A small effect size (g = 0.38) was found in MLPT to demonstrate poorer intellectual performance compared with those born at term. Moreover, MLPT adults exhibited greater odds for any psychiatric (OR 1.14), substance use (OR 1.16), mood (OR 1.06), and psychotic disorders (OR 1.40).

CONCLUSIONS

Despite inconsistency due to the methodologic differences between the selected studies, MLPT showed minor long-term effects into adulthood. However, more studies are needed, because prematurity seems to confer some vulnerability to biological and environmental factors that enhance susceptibility to adverse neurodevelopment outcomes.

Brain structure mediates the association between height and cognitive ability

Height and general cognitive ability are positively associated, but the underlying mechanisms of this relationship are not well understood. Both height and general cognitive ability are positively associated with brain size. Still, the neural substrate of the height-cognitive ability association is unclear. We used a sample of 515 middle-aged male twins with structural magnetic resonance imaging data to investigate whether the association between height and cognitive ability is mediated by cortical size. In addition to cortical volume, we used genetically, ontogenetically and phylogenetically distinct cortical metrics of total cortical surface area and mean cortical thickness. Height was positively associated with general cognitive ability and total cortical volume and cortical surface area, but not with mean cortical thickness. Mediation models indicated that the well-replicated height-general cognitive ability association is accounted for by individual differences in total cortical volume and cortical surface area (highly heritable metrics related to global brain size), and that the genetic association between cortical surface area and general cognitive ability underlies the phenotypic height-general cognitive ability relationship.

Short Stature: Is It a Psychosocial Problem and Does Changing Height Matter?

Some proponents of recombinant human growth hormone (rhGH) treatment in growth hormone-sufficient children cite height, as an isolated physical characteristic, as being associated with psychosocial morbidity. Others question the reliability of the evidence underpinning the quality-of-life rationale for treatment as well as the bioethics of rhGH treatment. The following questions are addressed: (1) Is short stature an obstacle to positive psychosocial adjustment? and (2) Does increasing height with rhGH treatment make a difference to the person's psychosocial adaptation and quality of life? Three clinical case examples are used to illustrate the complexities associated with decision-making surrounding rhGH use.

Protocol of the PSYCHOTSH study: association between neonatal thyroid stimulating hormone concentration and intellectual, psychomotor and psychosocial development at 4-5 year of age: a retrospective cohort study

Background

Several European countries, including Belgium, still suffer from mild iodine deficiency. Thyroid stimulating hormone (TSH) concentration in whole blood measured at birth has been proposed as an indicator of maternal iodine status during the last trimester of pregnancy. It has been shown that mild iodine deficiency during pregnancy may affect the neurodevelopment of the offspring. In several studies, elevated TSH levels at birth were associated with suboptimal cognitive and psychomotor outcomes among young children. This paper describes the protocol of the PSYCHOTSH study aiming to assess the association between neonatal TSH levels and intellectual, psychomotor and psychosocial development of 4–5 year old children. The results could lead to a reassessment of the recommended cut-off levels of 5 > mU/L used for monitoring iodine status of the population.

Methods

In total, 380 Belgian 4–5 year old preschool children from Brussels and Wallonia with a neonatal blood spot TSH concentration between 0 and 15 mU/L are included in the study. For each sex and TSH-interval (0–1, 1–2, 2–3, 3–4, 4–5, 5–6, 6–7, 7–8, 8–9 and 9–15 mU/L), 19 newborns were randomly selected from all newborns screened by the neonatal screening centre in Brussels in 2008–2009. Infants with congenital hypothyroidism, low birth weight and prematurity were excluded from the study. Neonatal TSH concentration was measured by the Autodelphia method in dried blood spots, collected by heel stick on filter paper 3 to 5 days after birth. Cognitive abilities and psychomotor development are assessed using the Wechsler Preschool and Primary Scale of Intelligence - third edition - and the Charlop-Atwell Scale of Motor coordination. Psychosocial development is measured using the Child Behaviour Check List for age 1½ to 5 years old. In addition, several socioeconomic, parental and child confounding factors are assessed.

Conclusions

This study aims to clarify the effect of mild iodine deficiency during pregnancy on the neurodevelopment of the offspring. Therefore, the results may have important implications for future public health recommendations, policies and practices in food supplementation. In addition, the results may have implications for the use of neonatal TSH screening results for monitoring the population iodine status and may lead to the definition of new TSH cut-offs for determination of the severity of iodine status and for practical use in data reporting by neonatal screening centres.

Mild iodine deficiency in pregnancy in Europe and its consequences for cognitive and psychomotor development of children: a review

Despite the introduction of salt iodization programmes as national measures to control iodine deficiency, several European countries are still suffering from mild iodine deficiency (MID). In iodine sufficient or mildly iodine deficient areas, iodine deficiency during pregnancy frequently appears in case the maternal thyroid gland cannot meet the demand for increasing production of thyroid hormones (TH) and its effect may be damaging for the neurodevelopment of the foetus. MID during pregnancy may lead to hypothyroxinaemia in the mother and/or elevated thyroid-stimulating hormone (TSH) levels in the foetus, and these conditions have been found to be related to mild and subclinical cognitive and psychomotor deficits in neonates, infants and children. The consequences depend upon the timing and severity of the hypothyroxinaemia. However, it needs to be noted that it is difficult to establish a direct link between maternal iodine deficiency and maternal hypothyroxinaemia, as well as between maternal iodine deficiency and elevated neonatal TSH levels at birth. Finally, some studies suggest that iodine supplementation from the first trimester until the end of pregnancy may decrease the risk of cognitive and psychomotor developmental delay in the offspring.

[Growth of preterm-born children]

Children born prematurely might experience a period of growth restriction just after birth. Catch-up growth begins during the first months of life and can be slow and progressive. These children may remain shorter and thinner throughout infancy and childhood compared to children born at term. In some cases, complete catch-up growth occurs only during adolescence. However, some children do not completely recover growth, and adults born prematurely are at increased risk of short stature. Impaired growth is more frequent in those born preterm and small for gestational age. Factors such as target height, birth weight, gestational age, neonatal morbidities and maternal education interfere in growth potential. Special attention should be given to children born preterm during the whole growth period.