The number of elderly patients seeking clinical treatment for memory problems 
will rise sharply in coming years as our population ages. These patients present 
a challenge for diagnosis and prognosis since cognitive problems in older 
patients can arise from many etiologies, some of which are curable. With the 
development of clinically available biomarkers for detecting Alzheimer's disease 
pathology in living patients, evaluation of cognitively impaired elderly 
patients is about to undergo a major paradigm shift. This article describes the 
two classes of biomarkers available for assessing Alzheimer's disease risk: 
those that indicate presence of amyloid pathology and those that provide 
evidence of neuronal injury and neurodegeneration. We argue that, currently, 
incorporation of biomarkers of neurodegeneration can help in patient prognosis 
whereas tests for amyloid, if used in isolation, have potential for harm. 
Amyloid tests are clinically useful only when evidence suggests progressive 
cognitive decline or neurodegeneration.