Brain development, gender and IQ in children

Abstract

Normal brain development during childhood is a complex and dynamic process for which detailed scientific information is lacking. MRI techniques, combined with methods for advanced image analysis, offer the potential to begin to construct a quantitative map of normal paediatric brain development in vivo. In this study we utilize volumetric analysis of high resolution brain images obtained from MRI to describe cerebral development and morphology in 85 normal children and adolescents ranging in age from 5 to 17 years. The results show that total cerebral volume is 10% larger in boys compared with girls. However, both boys and girls show little change in total cerebral volume after the age of 5 years. Increased cortical grey matter is the primary contributor to larger brain volume in boys, thus supporting the hypothesis that gender associated differences in brain size are related to differences in cortical neuronal density. Prominent, age-related changes in grey matter, white matter and CSF volumes are evident during childhood and appear to reflect ongoing maturation and remodelling of the CNS. Both boys and girls show a similar pattern of cerebral asymmetry; a rightward prominence of cortical and subcortical grey matter and a leftward prominence of CSF is observed. IQ is positively correlated with total cerebral volume in children, in particular, with the volume of cortical grey matter in the prefrontal region of the brain. Subcortical grey matter also contributes to the variance in IQ, although to a lesser extent than cortical grey volume. Quantitative knowledge of the developing human brain will play an increasingly greater role in improving sensitivity and specificity in the interpretation of brain abnormalities in patients within the clinical environment, as well as in groups of children with suspected brain dysfunction in the research setting.

Development of cortical and subcortical brain structures in childhood and adolescence: a structural MRI study

“…We also found evidence for subtle increases in brain volume, with a 9.5% difference between the youngest and oldest participants studied here. This finding is consistent with some studies in the literature (Jernigan et al 1991, Pfefferbaum et al 1996, but not with others (Reiss et al 1996). The cerebellum shows a comparable volume increase over the age range studied.…”

Course of intelligence deficits in early onset, first episode schizophrenia: a controlled, 5-year longitudinal study

“…In healthy children and adolescents, FSIQ is associated with whole-brain gray matter volume [42,57] and with left and right parietal, frontal, temporal lobe, and cingulate gray matter volumes [57]. In COS patients, an abnormal total, frontal, temporal, and parietal gray matter reduction has been demonstrated during adolescence without significant change in mean FSIQ [17].…”

Anatomical changes in the emerging adult brain: A voxel‐based morphometry study

“…Further, gray matter volume has been shown to have a quadratic developmental trajectory, with volume increasing during childhood, peaking during adolescence, and then decreasing once more during late adolescence and young adulthood [Gogtay et al, 2004;Reiss et al, 1996;Sowell et al, 2001]. The gray volume peak of each region differs temporally, with frontal and temporal lobes having the latest apex points [Giedd et al, 1999;Gogtay et al, 2004;Reiss et al, 1996]. Spatially, the dorsal, medial, and lateral areas of prefrontal cortex and posterior areas of temporal cortex have been shown to develop last, with the perisylvian region of the posterior temporal lobe having a characteristic late maturational pattern [Gogtay et al, 2004;Sowell et al, 2001].…”

“…Such a design also introduces an unknown amount of individual variation into the results [see Sowell et al, 2001]. Other studies have used a longitudinal design but investigated only gross volumetric changes in large predefined lobar regions [Giedd et al, 1999;Reiss et al, 1996]. Although this increases temporal specificity, this method of analysis precludes the possibility of knowing specifically where changes are occurring within the large volume.…”