Spinal Fluid Markers Predict Progression to Alzheimer Disease

A neurotoxic fragment of the amyloid-β (Aβ) protein, Aβ_1–42, and tau protein have long been incriminated as central players in the pathology of Alzheimer disease (AD). In a widely publicized study, investigators studied spinal fluid from 102 patients with well-characterized AD, 200 patients with mild cognitive impairment (MCI; a common precursor to AD), and 114 people with no measurable cognitive impairment. All participants were approximately the same age (median, 75).

Concentrations of Aβ_1–42 and tau proteins created an “AD signature” that was found in 90% of patients with AD, 72% of patients with MCI, and 36% of healthy participants. Healthy participants who exhibited the “AD signature” were much more likely than the population at large t…