[Biomarkers for early diagnosis of Alzheimer's disease: current update and future directions]

The increased prevalence of the sporadic form of Alzheimer's disease (AD) has become a significant health issue in the elderly population. The need for early diagnosis is imperative because this, along with the development of novel therapeutic treatments, would permit the rapid and perhaps more efficient treatment of these debilitating disorders early on.

Over the last decade, the potential use of certain biomarkers in the cerebrospinal fluid (CSF), and more recently, in the plasma has been investigated. Among the candidates studied includes the neurotoxic amyloid beta peptide and the Tau protein. However, although these two proteins have been clearly shown to be directly related to the pathophysiology of this disorder, it has proven difficult to establish a clear relationship between plasma or CSF levels of Abeta and Tau and the incidence and severity of AD in patients. This is due in part to differences in methodologies related to the detection sensitivity, as well as the variations in the biological data and consequent interpretation of the biochemical and biological data. Peripheral cells, in particular platelets and skin fibroblasts, could be an alternative solution as peripheral biological markers for the early diagnosis of AD. These cells are easily accessible from patients. Furthermore, they would provide a means not only to validate potential therapeutic strategies, but also to study the mechanisms involved in the development of AD, including APP processing.

A combined strategy using both a fundamental mechanistic and an analytical approach of patient peripheral cells will allow the identification of new biological markers for AD, and hence permit immediate therapeutic strategies to be implemented.