Heritability of brain volumes in older adults: the Older Australian Twins Study.

The relative contributions of genetic and environmental factors to brain structure change throughout the lifespan. Brain structures have been reported to be highly heritable in middle-aged individuals and younger; however, the influence of genes on brain structure is less studied in older adults. We performed a magnetic resonance imaging study of 236 older twins, with a mean age of 71.4 ± 5.7 years, to examine the heritability of 53 brain global and lobar volumetric measures. Total brain volume (63%) and other volumetric measures were moderately to highly heritable in late life, and these genetic influences tended to decrease with age, suggesting a greater influence of environmental factors as age advanced. Genetic influences were higher in men and on the left hemisphere compared with the right. In multivariate models, common genetic factors were observed for global and lobar total and gray matter volumes. This study examined the genetic contribution to 53 brain global and lobar volumetric measures in older twins for the first time, and the influence of age, sex, and laterality on these genetic contributions, which are useful information for a better understanding of the process of brain aging and helping individuals to have a healthy aging.