Measurement of Sitting Time in Older Adults With and Without Alzheimer's Disease.

Time spent being sedentary is associated with poorer cognitive function and risk of developing Alzheimer's disease (AD). The present study aimed to compare patterns of sitting in a free living environment among older adults with and without early stage AD who were similar in physical limitations, body mass, and cardiorespiratory capacity. We also compared estimates of sitting patterns between two different monitors (postural and non-postural) with different body placements (thigh-worn vs. hip-worn). Comparing older adults without cognitive impairment to those with early AD, we found that although there was no difference in the total amount of daily sitting time (p = .522), the AD group tended to have longer durations of sitting than those without AD. Inclinometry data from the hip-worn ActiGraph GT3X+ consistently underestimated time spent sitting compared to the thigh worn monitor (hours per day, proportion of waking hours, number of sitting bouts greater than 30 minutes, and duration of sitting bouts). Our results have implications for prevention strategies to reduce sedentary time, which is predominantly sitting, in persons with cognitive impairment and highlight the importance of monitor selection and placement for the accurate assessment of sitting patterns in this population.