Physical frailty could lead to rapid cognitive decline in aged, Chicago researchers have confirmed.
They chose approximately 40 retirement communities across the Chicago metropolitan area as their setting, and more than 750 older persons without cognitive impairment were enrolled.
Physical frailty, based on four components (grip strength, timed walk, body composition, and fatigue), was assessed at baseline, and cognitive function was assessed annually. Proportional hazards models adjusted for age, sex, and education were used to examine the association between physical frailty and the risk of incident mild cognitive impairment (MCI).
During up to 12 years of annual follow-up, 305 of 761 (40%) persons developed MCI. In a proportional hazards model adjusted for age, sex, and education, physical frailty was associated with a high risk of incident MCI, such that each one-unit increase in physical frailty was associated with a 63% increase in the risk of MCI. This association persisted in analyses that required MCI to persist for at least 1 year and after controlling for depressive symptoms, disability, vascular risk factors, and vascular diseases. Furthermore, a higher level of physical frailty was associated with a faster rate of decline in global cognition and five cognitive systems (episodic memory, semantic memory, working memory, perceptual speed, and visuospatial abilities).
The researchers led by Patricia Boyle, Rush Alzheimer's Disease Center, concluded, "Physical frailty is associated with risk of MCI and a rapid rate of cognitive decline in aging." The findings have been published in the Journal of the American Geriatric Society.
A previous study has shown that physical frailty among older adults can be an early indicator of the presence of abnormal brain plaque and tangles, all characteristics of Alzheimer's disease pathology.
The Alzheimer''s disease pathology was associated with physical frailty in older persons both with and without dementia," said study author Aron S. Buchman, MD, with Rush University Alzheimer''s Disease Center in Chicago and member of the American Academy of Neurology.
"The level of frailty was approximately two times higher in a person with a high level of AD pathology compared with a person with a low level of AD pathology," Buchman added.
Previous study on the same group while they were alive showed that people who are physically frail with no cognitive impairment appeared to be at higher risk of developing Alzheimer''s disease as compared to those who were less frail.
"Together both of these studies suggest that frailty can be an early indicator of Alzheimer''s disease pathology and may appear before memory loss," said Buchman.