Plasma Biomarkers Associated With the Apolipoprotein E Genotype and Alzheimer Disease

Abstract

Alzheimer disease (AD) is a progressive neurodegenerative disorder estimated to affect 27 million individuals worldwide, with numbers doubling every 20 years.¹ Although current diagnostic standards require the manifestation of dementia before diagnosis, neuropathologic features of AD occur well before the onset of dementia.² Studies^3-5 examining patients with prodromal AD that has progressed to dementia have identified a symptomatic predementia stage characterized by deficits in episodic memory and executive function. In addition, results of longitudinal natural history studies^3,4,6 examining biomarker changes have led to a general recognition that predementia stages of AD can be identified using cerebrospinal fluid (CSF) Aβ42 and t-tau/p-tau profiles, positron emission tomography (PET) amyloid imaging, and volumetric magnetic resonance imaging biomarker data. Furthermore, CSF studies and PET can help to confirm AD pathologic changes in patients diagnosed as having dementia of the Alzheimer type. As a result, revisions to the current diagnostic criteria are under consideration that incorporate CSF testing and imaging as aids in the diagnosis of and risk assessment for AD.^7-9