CSF markers for pathogenic processes in Alzheimer's disease: diagnostic implications and use in clinical neurochemistry.

In view of current (acetylcholine esterase (AChE) inhibitors) and future (e.g. gamma-secretase inhibitors) therapeutic compounds for treatment of Alzheimer's disease (AD), the development and evaluation of cerebrospinal fluid (CSF) biomarkers for AD has become a rapidly growing research field. Diagnostic biomarkers for AD would be especially valuable as aids to diagnosis early in the course of the disease, when correct diagnosis is difficult, and when therapeutic compounds have the greatest potential for being effective. This paper reviews CSF biomarkers for AD, with emphasis on their role in the clinical diagnosis. The two most studied biochemical markers, CSF-tau and CSF-Abeta42, have high sensitivity to identify AD, but the specificity against other dementias is lower. The addition of phosphorylated tau (P-Tau) seems to increase the specificity for the diagnosis of AD, since normal levels are found in both frontotemporal and Lewy body dementia, and in cerebrovascular disease. These CSF markers may be useful as diagnostic aids, especially to discriminate early or incipient AD from age-associated memory impairment, depression, and some secondary dementias.