C. P. Kaiser

Measuring amyloid-beta (Abeta) protein levels in cerebrospinal fluid (CSF) and using positron emission tomography (PET) to image amyloid in the brain might become the best diagnostic test for presymptomatic Alzheimer disease (AD), according to a study published online in December 2005 and appearing in the March issue of Annals of Neurology.

Often, a clinical diagnosis of AD comes too late for an individual to benefit from treatment. Clinicians can assign the diagnosis of mild cognitive impairment (MCI) to patients with memory complaints, but they cannot state emphatically which of these individuals will progress to AD. Typically, about 10% to 15% of persons diagnosed with MCI convert to AD within a year, while 30% to 40% do not convert--at least not for another 6 to 8 years.