Examination of the Common Cause Account in a Population-Based Longitudinal Study with Narrow Age Cohort Design

Abstract

Background: The common cause account suggests that there is a third factor causing aging effects in both sensory and cognitive functioning, hypothesized to be the integrity of the central nervous system [Lindenberger and Baltes; Psychol Aging 1994;9:339–355]. Importantly, the common cause account was developed based on cross-sectional data, which are especially biased by cohort effects. However, cohort effects can be controlled for in narrow age cohort (NAC) designs and by longitudinal examination. Findings from the few longitudinal studies that have studied the relation between age-related changes in sensory and cognitive functions are complex and give only partial support to the common cause account. Objective: The present paper examines the common cause account within a longitudinal setting. Method: Our study is unique in the sense that it tests the common cause account within a longitudinal NAC design using data from the Betula project. The participants (n = 1,057) were in the age range of 45–90 years. Results: The findings indicate that the relationship between sensory and memory functioning in both a longitudinal age-heterogeneous and a longitudinal NAC design are much weaker than that detected by an age-heterogeneous cross-sectional design. Conclusion: The demonstrated weak age-associated sensory-cognitive link raises questions regarding the explanatory value of the common cause account and related theoretical accounts for accounting for age-related cognitive changes.