Search for a common cause factor amongst cognitive, speed and biological variables using narrow age cohorts

Abstract

Background: Cross-sectional studies have demonstrated that age-related effects on many cognitive and biological functioning variables are shared. A number of theories postulate that these associations arise from a common causal mechanism responsible for change across a wide range of functions. However, it has been claimed that the finding of shared variance among variables in these studies may be spurious because most studies have been cross-sectional and based on age-heterogeneous samples. Objective: To examine evidence for changes with age in variance shared by cognitive variables using a narrow-age cohort design. Methods: Three samples of adults with age ranges 20-24 years (n = 2,404), 40..