Decreased-Amyloid 1-42 and Increased Tau Levels in Cerebrospinal Fluid of Patients With Alzheimer Disease

WHILE THE EXACT BIOLOGIcal cascade associated with Alzheimer disease (AD) is only partially understood, many potential biomarkers of this disease process are known. Two of the most obvious candidates are -amyloid1-42 and tau proteins, as they are intimately related to the pathognomonic features of amyloid plaques and neurofibrillary tangles in the AD brain. Multiple previous studies have reported decreases in cerebrospinal fluid (CSF) measures of -amyloid. Similarly, CSF measures of tau have routinely showed considerable elevations of this peptide in AD cases worldwide. Some authors have reported that these 2 measures alone can accurately differentiate clinically diagnosed AD cases from controls more than 85% of the time. Studies of CSF in AD patients have used widely varying methods and nomenclature for assessing and describAuthor Affiliations are listed at the end of this article. Corresponding Author and Reprints: Trey Sunderland, MD, Geriatric Psychiatry Branch, National Institute of Mental Health, 9000 Rockville Pike, Bethesda, MD 20892 (e-mail: trey@helix.nih.gov). Context Alzheimer disease (AD) is characterized by pathological results at autopsy of amyloid plaques and tau-associated neurofibrillary tangles, but the clinical diagnosis of AD is determined on the basis of medical history, cognitive symptoms, and exclusionary criteria. The search for antemortem biomarkers is intense and has focused on cerebrospinal fluid (CSF) -amyloid1-42 and tau proteins. Objectives To compare CSF -amyloid and tau levels in a new population of AD patients and controls. To perform a meta-analysis of studies of CSF -amyloid and tau levels in AD patients and controls.