Ratio of Aβ42/P-tau181p in CSF is associated with aberrant default mode network in AD.

The default mode network (DMN) is particularly relevant to Alzheimer's disease (AD) since its structures are vulnerable to deposition of amyloid. Decreased levels of β-amyloid1-42 (Aβ42) and increased total tau protein (T-tau) and tau phosphorylated at position threonine 181 (P-tau181p) in cerebrospinal fluid (CSF) have been established as valid biomarkers for the diagnosis and prognosis of AD. However, the relationship between CSF biomarkers and change in the DMN is still unknown. In this study we investigated the correlation between the functional connectivity within the DMN and the ratio of Aβ42/P-tau181p in the CSF. We found that the ratio of Aβ42/P-tau181p was moderately positively correlated with the functional connectivity within the DMN in the left precuneus/cuneus. This finding implicates that the brain functional connectivity within DMN is affected by pathological changes at early stage in AD. This may provide a better understanding of AD pathology progression and improve AD diagnosis.