An anonymous reader writes "A test that can confirm or rule out Alzheimer's disease at an early stage has been shown effective by US pathologists. 'With this test, we can reliably detect and track the progression of Alzheimer's disease,' said lead researcher Leslie Shaw with the University of Pennsylvania's Alzheimer's Disease Neuroimaging Initiative in Philadelphia. ... The new test is detailed in the journal Annals of Neurology. It measures the cerebral-spinal fluid concentration of two biochemicals associated with the disease — amyloid beta42 peptide and tau protein."