Actigraphy Data Reduction Protocol for the Memory and Aging Project
A sedentary lifestyle may present a risk for the onset and development of age-related cognitive impairment in older adults. This problem is compounded with the growing aging population in the United States. The Vanderbilt Memory & Aging Project (MAP) established a longitudinal cohort of older adults to examine the effect of vascular health on the brain as aging occurs. The MAP cohort includes 335 participants age 60-92 years, including 168 with mild cognitive impairment (MCI, 41% female, 73±8 years) and 167 sex-, race-, and age- matched controls with normal cognition (NC, 72±7 years, 41% female). As an optional part of the study, 227 participants were fitted with an ActiGraph GT9X Link accelerometer worn on the wrist for 10 days during their 18 month follow up visit. Quality control and data reduction practices for actigraphy data are imperative to capture accurate data and exclude inaccurate or irrelevant data in order to produce the most reliable outcomes. The current project aims to develop a protocol for actigraph data reduction and quality control for the MAP. Data reduction factors include how to define non-wear time, valid days of wear, spurious data, and how to calculate the minimum number of valid days to be used for analysis. An effective data reduction protocol will maximize data quality for the MAP study and prepare it for multiple analyses, such as the comparison between physical activity and neuropsychological testing. The developed protocol also supplements the growing body of knowledge about actigraphy data treatment protocols.