Previous studies have suggested that frailty, a common but poorly understood condition in older people, may predict the development of dementia. In this study, Rush University researchers examined 165 physically frail older adults before and after their deaths to investigate this connection. First, participants' frailty was evaluated by measuring their grip strength, timed walk, body composition, and fatigue. After death (at a mean age of 88.1 years), their brains were autopsied for evidence of AD, cerebral infarcts, and Lewy body disease.
Regression analyses controlling for age, chronic diseases, medications, and other factors showed an association between levels of frailty and of AD pathology but no association between frailty and cerebral infarcts or Lewy body disease. A higher level of AD pathology was associated with a higher level of frailty. The link was similar in people with and without dementia.
The researchers speculate that AD pathology may contribute to frailty by affecting parts of the brain that control movement. Or, AD and frailty may share a common cause. "These different mechanisms are not mutually exclusive and underscore the need for further studies of the relationship between AD and frailty," they conclude.
Buchman, A.S., et al. Physical frailty in older persons is associated with Alzheimer disease pathology. Neurology. 2008. 71:499-504.