Longitudinal Patterns of Brain Changes in a Community Sample in Relation to Aging and Cognitive Status

Abstract

Background: Aging and Alzheimer's disease (AD) are characterized by widespread cortical and subcortical atrophy. Though atrophy patterns between aging and AD overlap considerably, regional differences between these two conditions may exist. Few studies, however, have investigated these patterns in large community samples.

Objective: Elaborate longitudinal changes in brain morphometry in relation to aging and cognitive status in a well-characterized community cohort.

Methods: Clinical and neuroimaging data were compiled from 72 participants from the Cardiovascular Health Study-Cognition Study, a community cohort of healthy aging and probable AD participants. Two time points were identified for each participant with a mean follow-up time of 5.36 years. MRI post-processing, morphometric measurements, and statistical analyses were performed using FreeSurfer, Version 7.1.1.

Results: Cortical volume was significantly decreased in the bilateral superior frontal, bilateral inferior parietal, and left superior parietal regions, among others. Cortical thickness was significantly reduced in the bilateral superior frontal and left inferior parietal regions, among others. Overall gray and white matter volumes and hippocampal subfields also demonstrated significant reductions. Cortical volume atrophy trajectories between cognitively stable and cognitively declined participants were significantly different in the right postcentral region.

Conclusion: Observed volume reductions were consistent with previous studies investigating morphometric brain changes. Patterns of brain atrophy between AD and aging may be different in magnitude but exhibit widespread spatial overlap. These findings help characterize patterns of brain atrophy that may reflect the general population. Larger studies may more definitively establish population norms of aging and AD-related neuroimaging changes.

Keywords: Aging; Alzheimer’s disease; cognition; cognitive dysfunction; neuroimaging.

Fig. 1.

Longitudinal Changes in Cortical Volume. Regional differences in cortical volume, controlling for age, gender, BMI, eTIV, baseline cognition, and cognitive decline. Significant clusters include on the left hemisphere: superior frontal (A), superior parietal (B, C), inferior parietal (D), lateral occipital (E), medial orbitofrontal (F), and insular cortex (G), and on the right: superior frontal (H), lateral occipital (I), caudal middle frontal (J), and inferior parietal (K) regions. Quantitative data listed in Table 2.

Fig. 2.

Longitudinal Changes in Cortical Thickness. Regional differences in cortical thickness, controlling for age, gender, BMI, baseline cognition, and cognitive decline. Significant clusters include on the left hemisphere: superior frontal (A), inferior parietal (B), and fusiform region (C), and on the right: postcentral (D) and superior frontal (E) regions. Significant reductions in cortical volume were observed in all these clusters, except in the fusiform region, where cortical volume was increased. Quantitative data listed in Table 3.