Novel olfactory-based approach to measure risks of Alzheimer's disease and related dementias in diverse populations

Univ Of North Carolina Chapel Hill, Chapel Hill NC

Investigators

Abstract

Abstract The global burden of Alzheimer’s Disease (AD) and related dementias (ADRD) is projected to rise dramatically in the coming years. Memory is a key marker of cognitive deficits but its measurement in global studies of population aging is difficult. Word-based measurements of memory are challenging to interpret in populations where literacy is low, literacy inequality is high or multiple languages are in common use. These concerns are likely less important for olfactory-based assessments based on neurobiology. The entorhinal cortex is a key center for olfactory memory, linking the hippocampus with the olfactory bulb, and is among the first areas affected by AD neuropathological hallmarks, particularly neurofibrillary tangles. This project will rigorously evaluate the value-added of an olfactory-based approach to measuring memory function and adapt the protocol to facilitate its inclusion in population-based surveys across the globe, which will support production of comparable measurements across contexts. The Percepts of Odor Episodic Memory (POEM) is a recently developed protocol that measures olfactory memory and has been shown to be predictive of ADRD among older adults. We are fielding POEM in the Study of the Tsunami Aftermath and Recovery (STAR), a population- representative longitudinal survey of respondents who were living along the coast of Aceh, Indonesia, at the time of the 2004 Indian Ocean tsunami. We also collect a comprehensive battery of word- and drawing-based memory assessments as part of the Harmonized Cognitive Assessment Protocol (HCAP). Leveraging the design of STAR, and the fact that among those living in similar coastal communities, exposure to the tsunami can be treated as random, this project will provide new evidence on the long-term effects of exposure to the stresses of the disaster on memory function and cognitive aging. We will investigate the relationships among the array of memory measures and each of their relationships with age, sex and education as well as with exposure to the stressors of the tsunami. To place these results in context, we will analyze HCAP data from the U.S., England, India and Mexico to contrast the relationships with socioeconomic and demographic characteristics across places with different levels of literacy and language heterogeneity in an effort to identify generalizable findings within and across settings. Finally, we will field an Evaluation and Adaption Study (EASy) of POEM to develop a protocol that can be fielded at low cost in any field setting and provide measures of memory that are comparable across settings. EASy will evaluate how variation in assessment length and the number, order, type, range and familiarity of scents affects measurement in order to reduce the time-burden of the assessments and build a well-documented, ready-to-adopt protocol that is simple to implement in other field settings. Together, these data will afford the development of a robust olfactory memory test that can deployed across variable global populations at risk for ADRD.