Original Research ARTICLE
Lagged Coupled Changes between White Matter Microstructure and Processing Speed in Healthy Aging: A Longitudinal Investigation
- 1University Research Priority Program "Dynamics of Healthy Aging", University of Zurich, Switzerland
- 2University Research Priority Program "Dynamics of Healthy Aging" / Division of Gerontopsychology, University of Zurich, Switzerland
- 3University Research Priority Program "Dynamics of Healthy Aging" / Division of Neuropsychology, University of Zurich, Switzerland
Age-related differences in white matter (WM) integrity have been linked to lower performance in tasks of processing speed in healthy older individuals. However, only few studies have examined this link in a longitudinal setting. These investigations have been limited to the correlation of simultaneous changes in WM integrity and processing speed. Still little is known about the nature of age-related changes in WM integrity, i.e., regionally distinct vs. global changes. In the present study, we addressed these open questions by exploring whether previous changes in WM integrity were related to subsequent changes in processing speed (a) 1 year later, or (b) 2 years later. Furthermore, we investigated whether age-related changes in WM integrity were regionally specific or global. We used data from four occasions (covering 4 years) of the Longitudinal Healthy Aging Brain (LHAB) database project (N = 232; age range at baseline = 64 - 86). As a measure of WM integrity, we used mean fractional anisotropy (FA) in 10 major WM tracts averaged across hemispheres. Processing speed was measured with four cognitive tasks. Statistical analyses were conducted with bivariate latent change score (LCS) models. We found, for the first time, evidence for lagged couplings between preceding changes in FA and subsequent changes in processing speed 2 years, but not 1 year later in some of the WM tracts (anterior thalamic radiation, superior longitudinal fasciculus). Our results supported the notion that FA changes were different between regional WM tracts rather than globally shared, with some tracts showing mean declines in FA, and others remaining relatively stable across 4 years.
Keywords: white matter microstructure, processing speed, Longitudinal, Coupled changes, healthy aging, latent change score model, structural equation modeling (SEM), fractional anisotropy
Received: 05 Dec 2018;
Accepted: 16 Oct 2019.
Copyright: © 2019 Oschwald, Mérillat, Liem, Röcke, Martin and Jäncke. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Ms. Jessica Oschwald, University of Zurich, University Research Priority Program "Dynamics of Healthy Aging", Zürich, CH-8006, Zürich, Switzerland, firstname.lastname@example.org