[Patients with mild cognitive impairment and a reduced CSF Aβ₁₋₄₂ protein progress rapidly to Alzheimer's disease].

Introduction: Some studies have shown that CSF amyloid-beta 1-42 (Aβ₁₋₄₂), total tau (T-tau) and tau phosphorylated at threonine 181 (P-tau(181p)) proteins are useful diagnostic markers for distinguishing between clinically stable mild cognitive impairment (MCI) patients and those who will develop Alzheimeŕs disease (AD). Our objective was to test the ability of this technique to discriminate in our cohort of MCI patients, according to the clinical outcome, one year after the lumbar puncture.

Material And Methods: A total of 36 MCI patients were included from the local hospital memory clinic. Using INNO-BIA Alzbio-3 reagents from Innogenetics, we measured CSF Aβ₁₋₄₂, T-tau and P-tau(181p) proteins, and calculated the T-tau/Aβ₁₋₄₂ y P-tau(181p)/Aβ₁₋₄₂ ratios. This project was approved by the local ethics committee.

Results: One year after the lumbar puncture, 14 MCI patients (38%) developed AD. These patients had lower Aβ₁₋₄₂ protein levels (285.3 vs 377 ng/ml, P<.02) and higher P-tau(181p)/Aβ₁₋₄₂ ratio (0,25 vs 0,16, p<.02) than the clinically stable patients.

Conclusions: Our MCI patients with lower Aβ₁₋₄₂ protein levels and an increased P-tau(181p) /Aβ₁₋₄₂ ratio progressed quickly to AD. These results may help to identify those MCI patients with a poorer prognosis.