Use of Alzheimer Disease Biomarkers:  Potentially Yes for Clinical Trials but Not Yet for Clinical Practice

Research in Alzheimer disease (AD) is rapidly moving toward the point of the earliest possible identification of the underlying disease processes. These include the accumulation of Aβ plaques, tau tangles, and neuron as well as synaptic loss, and it is likely that these do not all occur contemporaneously. Many investigators contend that, by the time the clinical symptoms appear, sufficient AD pathology and neurodegeneration have occurred, which if irreversible, may reduce the efficacy of disease-modifying therapy for clinically manifest AD.¹ As such, efforts are under way to try to identify the onset of these pathological processes that culminate in clinically manifest AD dementia. However, to accomplish this, the underlying pathology must be detected, possibly through the use of neuroimaging and chemical biomarker measures. In this issue of JAMA, Mattsson and colleagues² report their evaluation of the utility of cerebrospinal fluid (CSF) markers for AD in a large multicenter study.