Moderating Effect of Cortical Thickness on BOLD Signal Variability Age-Related Changes

Daiana R Pur; Roy A Eagleson; Anik de Ribaupierre; Nathalie Mella; Sandrine de Ribaupierre

doi:10.3389/fnagi.2019.00046

Moderating Effect of Cortical Thickness on BOLD Signal Variability Age-Related Changes

Front Aging Neurosci. 2019 Mar 12:11:46. doi: 10.3389/fnagi.2019.00046. eCollection 2019.

Authors

Daiana R Pur¹, Roy A Eagleson^{1

2}, Anik de Ribaupierre³, Nathalie Mella³, Sandrine de Ribaupierre^{1

4}

Affiliations

¹ School of Biomedical Engineering, Western University, London, ON, Canada.
² Department of Electrical and Computer Engineering, Western University, London, ON, Canada.
³ Department of Psychology, University of Geneva, Geneva, Switzerland.
⁴ Department of Clinical Neurological Sciences, Schulich School of Medicine, Western University, London, ON, Canada.

Abstract

The time course of neuroanatomical structural and functional measures across the lifespan is commonly reported in association with aging. Blood oxygen-level dependent signal variability, estimated using the standard deviation of the signal, or "BOLD_SD," is an emerging metric of variability in neural processing, and has been shown to be positively correlated with cognitive flexibility. Generally, BOLD_SD is reported to decrease with aging, and is thought to reflect age-related cognitive decline. Additionally, it is well established that normative aging is associated with structural changes in brain regions, and that these predict functional decline in various cognitive domains. Nevertheless, the interaction between alterations in cortical morphology and BOLD_SD changes has not been modeled quantitatively. The objective of the current study was to investigate the influence of cortical morphology metrics [i.e., cortical thickness (CT), gray matter (GM) volume, and cortical area (CA)] on age-related BOLD_SD changes by treating these cortical morphology metrics as possible physiological confounds using linear mixed models. We studied these metrics in 28 healthy older subjects scanned twice at approximately 2.5 years interval. Results show that BOLD_SD is confounded by cortical morphology metrics. Respectively, changes in CT but not GM volume nor CA, show a significant interaction with BOLD_SD alterations. Our study highlights that CT changes should be considered when evaluating BOLD_SD alternations in the lifespan.

Keywords: BOLD fMRI; aging; biomarker; cortical morphology; cortical thickness; neural processing; signal variability; structural alterations.