Both Aß and tau pathology appear to be associated with default mode network integrity before clinical onset of Alzheimer disease (AD), according to a study by Liang Wang, M.D., and colleagues at Washington University in St. Louis, Missouri.
Accumulation of Aß and tau proteins, the pathologic hallmarks of AD, starts years before clinical onset. Pathophysiological abnormalities in the preclinical phase of AD may be detected using cerebrospinal fluid (CSF) or neuroimaging biomarkers, according to the study background.
A total of 207 older adults with normal cognition participated in the cross-sectional group study. Researchers examined the relationship between default mode network integrity and cerebrospinal fluid biomarkers of Alzheimer disease pathology in cognitively normal older individuals using resting-state functional connectivity magnetic resonance imaging.
According to the study results, decreased cerebrospinal fluid Aß42 and increased cerebrospinal fluid phosphorylated tau181 were independently associated with reduced default mode network integrity, with the most prominent decreases in functional connectivity observed between the posterior cingulate and medial temporal regions (regions of the brain associated with memory). Observed reductions in functional connectivity were unattributable to age or structural atrophy in the posterior cingulate and medial temporal areas.
(JAMA Neurol. Published online August 19, 2013. doi:10.1001/.jamaneurol.2013.3253. Available pre-embargo to the media at http://media.
Editor's Note: Authors made conflict of interest disclosures. The study was supported by grants from the National Institute of Neurological Disorders and Stroke, National Institute of Mental Health, National Institute on Aging, and numerous other funding sources. Please see the articles for additional information, including other authors, author contributions and affiliations, financial disclosures, funding and support, etc.