Effects of Genetic and Environmental Factors on Cingulate Cortical Thickness on Brain Magnetic Resonance Imaging: A Normal Twin Study in East Asia

Twins have been studied to estimate the magnitudes of genetic and environmental effects on human phenotypes. The aim was to evaluate the genetic and environmental contributions to the cortical thickness of the cingulate region using brain magnetic resonance imaging of normal twins.

Three-dimensional T1-weighted brain imaging at 3T of 43 monozygotic pairs and 18 dizygotic pairs was performed. Cortical thickness was measured for each of the six regions of the cingulum. Twin analysis with a model involving the phenotype variance components of additive genetic effects (A), common environmental effects (C), and unique environmental effects (E) was performed to assess the magnitude of each genetic and environmental effect on cortical thickness.

The AE model including A and E factors was adopted in the twin analysis for most of the regions. The magnitude of the genetic effects was mostly high and varied in each region; the genetic effects were strong in both sides of the anterior cingulate region, and the environmental effects were slightly strong in both sides of the posterior and marginal cingulate regions.

Cortical thickness was affected mainly by genetic factors in the cingulate region.