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Introduction It has been proposed that the signal distribution on tau positron emission tomography (PET) images could be used to define pathologic stages similar to those seen in neuropathology. Methods Three topographic staging schemes for tau PET, two sampling the temporal and occipital subregions only and one sampling cortical gray matter across the major brain lobes, were evaluated on flortaucipir F 18 PET images in a test-retest scenario and from Alzheimer's Disease Neuroimaging Initiative 2. Results All three schemes estimated stages that were significantly associated with amyloid status and when dichotomized to tau positive or negative were 90% to 94% concordant in the populations identified. However, the schemes with fewer regions and simpler decision rules yielded more robust performance in terms of fewer unclassified scans and increased test-retest reproducibility of assigned stage. Discussion Tau PET staging schemes could be useful tools to concisely index the regional involvement of tau pathology in living subjects. Simpler schemes may be more robust.

Digital technology is transforming the development of drugs for Alzheimer's disease and was the topic of the Alzheimer's Association's Research Roundtable on its May 23-24, 2017 meeting. Research indicates that wearable devices and unobtrusive passive sensors that enable the collection of frequent or continuous, objective, and multidimensional data during daily activities may capture subtle changes in cognition and functional capacity long before the onset of dementia. The potential to exploit these technologies to improve clinical trials as both recruitment and retention tools as well as for potential end points was discussed. The implications for the collection and use of large amounts of data, lessons learned from other related disease areas, ethical concerns raised by these new technologies, and regulatory issues were also covered in the meeting. Finally, the challenges and opportunities of these new technologies for future use were discussed.

Alzheimer disease (AD), the most common form of dementia, is a neurodegenerative disorder characterized by neuronal and synaptic loss. Despite its high prevalence and great cost to society, there is no definitive premortem test for AD (1)(2). The diagnosis of probable or possible AD is based on a history of insidious onset and progressive impairment of memory as well as loss of other cognitive functions (3). The most important clinical task is the exclusion of reversible causes of dementia, most commonly vascular dementia. It is of little comfort to treating physicians and family members that postmortem examination of the brain by the pathologist is the only reliable diagnostic test for AD. Typically, microscopic examination of stained sections of brain taken from cortical and limbic brain regions reveals the hallmark changes of AD, namely, accumulation of intracellular neurofibrillary tangles and extracellular amyloid plaques. Neurofibrillary tangles are composed mainly of abnormally hyperphosphorylated tau protein (P-TAU). The extracellular amyloid plaques are composed of the 40- and 42-amino acid-long β-amyloid peptides [Aβ(1–40) and Aβ(1–42)]. Several neuropathologic subtypes of AD have been described, depending principally on the cortical regions most affected by neuronal loss, and the rates …