Cerebrospinal fluid markers for prediction of Alzheimer's disease.

A major diagnostic challenge when people seek advice for cognitive dysfunction is to differentiate between mild cognitive impairment (MCI) and incipient Alzheimer's disease (AD). We show that a combination of three cerebrospinal fluid biochemical markers, total-tau, phospho-tau and beta-amyloid(1-42), can detect incipient AD among patients fulfilling the criteria for MCI with a sensitivity of 68% (95% CI 45-86%) and a specificity of 97% (95% CI 83-100%). The usefulness of these markers is further emphasized by the finding of a positive predictive value of 94% and a negative predictive value of 81%.