CSF Aβ but not p-Tau differentiates aMCI from SCI.

Aim: Individuals with amnestic mild cognitive impairment (aMCI) are at a high risk to develop Alzheimer's disease (AD). We compared CSF levels of biomarkers of amyloidosis (Aβ) and neurodegeneration (p-Tau) in individuals with aMCI and with subjective cognitive impairment (SCI) in order to ascertain diagnostic accuracy and predict the odds ratio associated with aMCI.

Methods: We collected CSF of individuals clinically diagnosed with aMCI (33) and SCI (12) of a memory clinic of Southern Brazil. Levels of Aβ and p-Tau were measured by immunoenzymatic assay. Participants also underwent neuropsychological testing including the verbal memory test subscore of the Consortium to Establish a Registry for Alzheimer's Disease (VM-CERAD).

Results: CSF concentration of Aβ was significantly lower (p: .007) and p-Tau/Aβ ratio higher (p: .014) in aMCI individuals than in SCI. However, isolate p-Tau levels were not associated with aMCI (p: .166). There was a statistically significant association between Aβ and p-Tau (R: 0.177; β: -4.43; p: .017). ROC AUC of CSF Aβ was 0.768 and of the p-Tau/Aβ ratio equals 0.742. Individuals with Aβ < 823 pg/mL levels were 6.0 times more likely to be diagnosed with aMCI (p: .019), with a 68.9% accuracy. Those with p-Tau/Aβ ratio > 0.071 were at 4.6 increased odds to have aMCI (p: .043), with a 64.5% accuracy. VM-CERAD was significantly lower in aMCI than among SCI (p: .041).

Conclusion: CSF Aβ, but not p-Tau level was significantly associated with aMCI.