Relation between general cognitive ability and gray to white matter intensity ratio across the cortex

Many studies have shown the associations between general cognitive ability and aspects of brain structure. For instance, IQ has been associated, among other things, with total brain volume, gray matter density, cortical... [ view full abstract ]

Many studies have shown the associations between general cognitive ability and aspects of brain structure. For instance, IQ has been associated, among other things, with total brain volume, gray matter density, cortical thickness, corpus callosum thickness and area, shape of the basal ganglia, as well as various indices of cortical folding complexity and white matter integrity. Here, we explore the association between cognitive ability and gray to white matter intensity ratio. This measure is thought to be in part influenced by myelination of the lower layers of the cortex and, in children, to reflect cortical maturation. We report associations between full scale IQ derived from the Wechsler Abbreviated Scale of Intelligence (WASI) and gray to white matter intensity ratio adjusted for age, gender, and scanner in a large sample of healthy children and adolescents (ages 6-18, n= 203) representative of the US population. Significant positive associations were shown between WASI IQ and gray to white matter intensity ratio in most multimodal association areas. Results are consistent with a distributed model of intelligence.