Genetic and environmental architecture of processing speed across midlife.

Processing Speed (PS) is an important domain in cognitive aging that is characterized by multiple related but nonidentical abilities. Few studies have directly investigated the relationships among PS measures, and none have used genetically informed methods. In this study, we examined the relationship between measures of PS at up to two time points during middle age.We examined data from 1,262 middle-aged men when the sample was at a mean age of...