Bivariate heritability of total and regional brain volumes: the Framingham Study.

Heritability and genetic and environmental correlations of total and regional brain volumes were estimated from a large, generally healthy, community-based sample, to determine if there are common elements to the genetic influence of brain volumes and white matter hyperintensity (WMH) volume. There were 1538 Framingham Heart Study participants with brain volume measures from quantitative magnetic resonance imaging who were free of stroke and other neurologic disorders that might influence brain volumes and who were members of families with at least 2 Framingham Heart Study participants. Heritability was estimated using variance component methodology and adjusting for the components of the Framingham stroke risk profile. Genetic and environmental correlations between traits were obtained from bivariate analysis. Heritability estimates ranging from 0.46 to 0.60 were observed for total brain, WMH, hippocampal, temporal lobe, and lateral ventricular volumes. Moderate, yet significant, heritability was observed for the other measures. Bivariate analyses demonstrated that relationships between brain volume measures, except for WMH, reflected both moderate to strong shared genetic and shared environmental influences. This study confirms strong genetic effects on brain and WMH volumes. These data extend current knowledge by showing that these 2 different types of magnetic resonance imaging measures do not share underlying genetic or environmental influences.