Head Growth and Intelligence from Birth to Adulthood in Very Preterm and Term Born Individuals

Abstract

Objectives: The aim of this study was to investigate the effects of infant and toddler head growth on intelligence scores from early childhood to adulthood in very preterm (<32 weeks gestational age; VP) and/or very low birth weight (<1500 g; VLBW) and term born individuals. Methods: 203 VP/VLBW and 198 term comparisons were studied from birth to adulthood as part of the prospective geographically defined Bavarian Longitudinal Study (BLS). Head circumference was assessed at birth; 5, 20 months; and 4 years of age. Intelligence was assessed with standardized tests in childhood (6 and 8 years: K-ABC) and at 26 years (Wechsler Adult Intelligence Scale, WAIS). Structural equation modeling (SEM) was used to model the effect of head growth on IQ. Results: On average, VP/VLBW had lower head circumference at birth (27.61 cm vs. 35.11 cm, mean difference 7.49, 95% confidence interval [7.09–7.90]) and lower adult intelligence scores (88.98 vs. 102.54, mean difference 13.56 [10.59–16.53]) than term born comparison individuals. Head circumference at birth (e.g., total effect β=.48; p<.001 for adult IQ) and head growth in childhood predicted intelligence development from age 6 to 26 years in both VP/VLBW and term born individuals (70% of variance in adult IQ explained by full model). Effects of gestation and birth weight on intelligence were fully mediated by head circumference and growth. Conclusions: This longitudinal investigation from birth to adulthood indicates head growth as a proxy of brain development and intelligence. Repeated early head circumference assessment adds valuable information when screening for long-term neurocognitive risk. (JINS, 2019, 25, 48#x2013;56)

Small for gestational age—cognitive performance from infancy to adulthood: an observational study

“…Future research should investigate how references differ on birthweight centiles as well as the binary SGA versus AGA cut‐offs used here, as the relationship between birthweight centile and IQ is probably continuous 25 . Additionally, other anthropological measurements, such as head circumference, may provide better utility in predicting long‐term cognitive outcomes 26 …”

Decreased cortical thickness mediates the relationship between premature birth and cognitive performance in adulthood

“…This is necessary when analyzing structures that scale with head size, such as volume and surface area; however, CTh of a given area does not correlate with TIV (Barnes et al, 2010; Pakkenberg & Gundersen, 1997). Furthermore, head circumference and growth, measures closely related to TIV, have been identified to predict intelligence development and thus can be considered a marker of general developmental impairment after premature birth (Jaekel, Sorg, Baeuml, Bartmann, & Wolke, 2019). Since the purpose of our study is to determine whether developmental impairment after premature birth leads to alterations in CTh, adding TIV would eliminate important variance.…”

Small for Gestational Age-Cognitive Performance From Infancy to Adulthood: An Observational Study

“…11 Future research should investigate how references differ on birthweight percentiles as well as the binary SGA vs AGA cut-offs used here, as the relationship between birthweight percentile and IQ is likely continuous 25 . Additionally, other anthropological measurements, such as head circumference, may provide better utility in predicting long term cognitive outcomes 26 .…”