Intra-Individual Variability of Physical Activity in Older Adults With and Without Mild Alzheimer's Disease.
Physical activity shows promise for protection against cognitive decline in older adults with and without Alzheimer's disease (AD). To better understand barriers to adoption of physical activity in this population, a clear understanding of daily and weekly activity patterns is needed. Most accelerometry studies report average physical activity over an entire wear period without considering the potential importance of the variability of physical activity. This study evaluated individual differences in the amount and intra-individual variability of physical activity and determined whether these differences could be predicted by AD status, day of wear, age, gender, education, and cardiorespiratory capacity. Physical activity was measured via accelerometry (Actigraph GT3X+) over one week in 86 older adults with and without AD (n = 33 and n = 53, respectively). Mixed-effects location-scale models were estimated to evaluate and predict individual differences in the amount and intra-individual variability of physical activity. Results indicated that compared to controls, participants with AD averaged 21% less activity, but averaged non-significantly greater intra-individual variability. Women and men averaged similar amounts of physical activity, but women were significantly less variable. The amount of physical activity differed significantly across days of wear. Increased cardiorespiratory capacity was associated with greater average amounts of physical activity. Investigation of individual differences in the amount and intra-individual variability of physical activity provided insight into differences by AD status, days of monitor wear, gender, and cardiovascular capacity. All individuals regardless of AD status were equally consistent in their physical activity, which may have been due to a highly sedentary sample and/or the early disease stage of those participants with AD. These results highlight the value of considering individual differences in both the amount and intra-individual variability of physical activity.
Department of Clinical Psychology, KU Alzheimer's Disease Center, University of Kansas, Lawrence, Kansas, United States of America.
Amber
http://orcid.org/0000-0002-8385-1091
A
Watts
Department of Medicine, Creighton University, Omaha, Nebraska, United States of America.
Ryan W
RW
Walters
Research Design and Analysis Unit, Schiefelbusch Institute for Lifespan Studies, University of Kansas, Lawrence, Kansas, United States of America.
Lesa
L
Hoffman
Department of Educational Psychology, University of Kansas, Lawrence, Kansas, United States of America.
Jonathan
J
Templin
D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000453:epidemiology / Q000503:physiopathology*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D009043:Motor Activity