Donald J. Johannessen Lenox Hill Hospital
Richard C. Mohs Mount Sinai School of Medicine; Bronx Veterans Administration Medical Center
Brian A. Lawlor Mount Sinai School of Medicine; Bronx Veterans Administration Medical Center
Larry D. Altstiel Mount Sinai School of Medicine
The development of an early marker, or preclinical diagnostic test, for Alzheimer's disease (AD) would be important for several reasons. AD is the most common dementing illness of later life ( Katzman, 1986). Several problems hamper efforts to identify the cause of and treatments for AD. The diagnosis of AD can be made with certainty only when clinical and neuropathologic data obtained by autopsy or brain biopsy are available. Clinically, the diagnosis is made by determining that a patient has symptoms consistent with AD and then eliminating other causes of dementia, arriving at a clinical diagnosis of probable AD ( McKhann et al., 1984).
In all likelihood, symptoms of AD are evident only long after pathophysiologic changes characteristic of the disease have started. By a marker of AD, we mean some measure that reflects the pathophysiologic processes of AD. By an early marker, we mean a marker that can be used prior to the time when a clinical diagnosis of probable AD can be made. The accuracy of this clinical diagnosis varies. In many series, the autopsy confirmation rate is about 80% ( Joachim, Morris, & Selkoe, 1988; Sulkava, Hattia, Paetau, Wikstrom, & Palo, 1983). Rates can be higher for well-characterized late onset patients ( Morris, McKeel, Fulling, Torack, & Berg, 1988). Younger subjects and those with mild