An inflammatory and trophic disconnect biomarker profile revealed in Down syndrome plasma: Relation to cognitive decline and longitudinal evaluation

INTRODUCTION: Given that Alzheimer's pathology develops silently over decades in Down syndrome (DS), prognostic biomarkers of dementia are a major need. METHODS: We investigated the plasma levels of Aβ, proNGF, tPA, neuroserpin, metallo-proteases and inflammatory molecules in 31 individuals with DS (with and without dementia) and in 31 healthy controls. We examined associations between biomarkers and cognitive decline. RESULTS: Aβ40 and Aβ42 were elevated in DS plasma compared to controls, even in DS individuals without dementia. Plasma Aβ correlated with the rate of cognitive decline across 2 years. ProNGF, MMP-1, MMP-3, MMP-9 activity, TNF-α, IL-6, and IL-10 were higher in DS plasma, even at AD-asymptomatic stages. Declining plasma Aβ42 and increasing proNGF levels correlated with cognitive decline. A combined measure of Aβ and inflammatory molecules was a strong predictor of prospective cognitive deterioration. CONCLUSIONS: Our findings support the combination of plasma and cognitive assessments for the identification of DS individuals at risk of dementia.