Cerebrospinal fluid biomarkers for Alzheimer's disease

Alzheimer's disease (AD), Lewy-body disease (LBD) and Frontotemporal Dementia (FTD) are the major causes of memory impairment and dementia. As new therapeutic agents are under testing for the different diseases, there is an ultimate need for an early differential diagnosis. Biomarkers can serve as early diagnostic indicators or as markers of preclinical pathological changes. Therefore, diagnostic markers in the cerebrospinal fluid (CSF) have become a rapidly growing research field, since CSF is in direct contact with the central nervous system (CNS) and is supposed to reflect the brain environment.So far, three CSF biomarkers, the 42 amino acid form of ß-amyloid (Aß), total tau and phosphotau, have been validated in a number of studies. These CSF markers have high sensitivity to differentiate early and incipient AD from normal aging, depression, alcohol dementia and Parkinson's disease, but lower specificity against other dementias, such as FTD and LBD.This chapter reviews CSF biomarkers for AD, with emphasis on their role in the clinical diagnosis.