Is there a common underlying mechanism for age-related decline in cortical thickness?

The aim of this study was to derive a causal model of age-related grey matter atrophy across the cortex on the basis of cortical thickness measures using surface reconstruction of structural magnetic resonance images. Using confirmatory factor analysis, it was shown that the observed interregional correlations matrix between thickness measures could most accurately be accounted for by a single common age-related mechanism. This common factor did not predict cortical thickness directly, but exerted differential effects on individual region through independent lobe-specific systems. This model reconciles two seemingly mutually exclusive hypotheses, namely, the existence of different decay functions being caused by the same underlying mechanism.