Cortical surface area and IQ in very-low-birth-weight (VLBW) young adults

Abstract

Introduction: Quantitative MRI measurements have revealed abnormalities in cortical development in children born preterm with very-low-birth-weight (VLBW). These children also have increased risk of cognitive deficits that persist into adulthood. The aim of this study was to investigate cortical surface area in VLBW young adults at age 19 compared with controls and to see whether surface area change was associated with cognitive function in the VLBW group.

Methods: Thirty-eight VLBW (BW ≤ 1500 g) and 59 control participants were included in the study. Cognitive function was assessed by Wechsler Adult Intelligence Scale (WAIS)-III. The MRI scanning was performed at 1.5 T, and for the morphometric analyses of cortical surface area the FreeSurfer software was used.

Results: Reduction in cortical surface area was seen in ventrolateral prefrontal, temporal and parietal regions in the VLBW group. Intelligence quotient (IQ) scores were reduced and correlated with surface area reduction in superior and inferior frontal gyri, and in medial temporal and occipital regions in the VLBW group. Brodmann areas (BAs) included in the group differences and in the IQ correlation in the VLBW group were located to the inferior frontal gyrus (BA 11, 12, 44, 45, 47), isthmus (BA 25), the superior parietal (BA 7), the inferior temporal (BA 20) and the parahippocampal gyri (BA 28, 34, 35, 36, 37). The IQ indices that made the largest contribution to the associations between IQ and surface areal change in the VLBW group were the Working Memory and the Processing Speed indices.

Conclusions: Our study indicates that permanent deviations in cortical surface area still present in adulthood may explain the increased prevalence of cognitive impairments in preterm born VLBW individuals.

Keywords: Brodmann areas; Cortical surface area; IQ; MRI; Very-low-birth-weight; Working memory.