AUTHOR=Scarapicchia Vanessa , Mazerolle Erin L. , Fisk John D. , Ritchie Lesley J. , Gawryluk Jodie R. 

TITLE=Resting State BOLD Variability in Alzheimer’s Disease: A Marker of Cognitive Decline or Cerebrovascular Status?

JOURNAL=Frontiers in Aging Neuroscience

VOLUME=10

YEAR=2018

URL=https://www.frontiersin.org/journals/aging-neuroscience/articles/10.3389/fnagi.2018.00039

DOI=10.3389/fnagi.2018.00039

ISSN=1663-4365

ABSTRACT=<p><bold>Background:</bold> Alzheimer’s disease (AD) is a neurodegenerative disorder that may benefit from early diagnosis and intervention. Therefore, there is a need to identify early biomarkers of AD using non-invasive techniques such as functional magnetic resonance imaging (fMRI). Recently, novel approaches to the analysis of resting-state fMRI data have been developed that focus on the moment-to-moment variability in the blood oxygen level dependent (BOLD) signal. The objective of the current study was to investigate BOLD variability as a novel early biomarker of AD and its associated psychophysiological correlates.</p><p><bold>Method:</bold> Data were obtained from the Alzheimer’s Disease Neuroimaging Initiative (ADNI) 2 database from 19 participants with AD and 19 similarly aged controls. For each participant, a map of BOLD signal variability (SD<sub>BOLD</sub>) was computed as the standard deviation of the BOLD timeseries at each voxel. Group comparisons were performed to examine global differences in resting state SD<sub>BOLD</sub> in AD versus healthy controls. Correlations were then examined between participant SD<sub>BOLD</sub> maps and (1) ADNI-derived composite scores of memory and executive function and (2) neuroimaging markers of cerebrovascular status.</p><p><bold>Results:</bold> Between-group comparisons revealed significant (<italic>p</italic> &lt; 0.05) increases in SD<sub>BOLD</sub> in patients with AD relative to healthy controls in right-lateralized frontal regions. Lower memory scores and higher WMH burden were associated with greater SD<sub>BOLD</sub> in the healthy control group (<italic>p</italic> &lt; 0.1), but not individuals with AD.</p><p><bold>Conclusion:</bold> The current study provides proof of concept of a novel resting state fMRI analysis technique that is non-invasive, easily accessible, and clinically compatible. To further explore the potential of SDBOLD as a biomarker of AD, additional studies in larger, longitudinal samples are needed to better understand the changes in SDBOLD that characterize earlier stages of disease progression and their underlying psychophysiological correlates.</p>