Longitudinal Changes in Grey Matter Correspond to Changes in Cognition Across the Lifespan: Implications for Theories of Cognition

Background: Interpretations of brain and cognitive reserve were tested by assessing the parallel, longitudinal relationship between grey matter atrophy and cognitive decline in an adult lifespan sample. Method: Cognitive battery and structural MRI images were assessed in 463 healthy participants of age 20-89. Participants were assessed up to 3 times over up to 10 years. Change-over-time in cortical grey mater, subcortical grey matter, and general cognitive ability were modeled via latent growth curve modeling, and covariance of these latent change scores were assessed via parallel-process latent change modeling. Result: Latent change in general cognition was found to significantly covary with latent change in both cortical grey matter. Cortical grey matter volume, subcortical grey matter volume, and cognition at baseline were found to significantly relate to longitudinal cognitive decline, such that individuals with higher volume and better cognitive performance experienced less decline over the observation period. Conclusion: Individual differences in cognitive and grey matter decline are demonstrably related. Both cognitive and grey matter resources at baseline reserve to differentiate longitudinal patterns of cognitive decline. Grey matter volume appears to provide a good estimate of what some refer to as "brain reserve" and the latent cognition factor estimated "cognitive reserve." Overall, these latent measures may be parsimoniously viewed as measures of neoro-cognitive resource that do not require invoking the construct of "reserve" to explain individual differences in brain structure and cognition.