Physical Frailty Could Predict Alzheimer's Disease
WEDNESDAY Aug. 13, 2008 -- Physical frailty among the elderly may be linked to early Alzheimer's disease, regardless of whether or not patients develop dementia, new research reveals.
The finding, based on brain autopsies of deceased elderly patients, raises the notion that motor impairment in the elderly is an early symptom of Alzheimer's -- one that appears before mental decline.
It could also turn out to be that frailty and Alzheimer's are not directly linked but stem from a common origin, researchers say.
"What we know is that if you see a very frail person next to somebody not so frail, the very frail person is more likely to have Alzheimer's pathology in their brain when they die," said study lead author Dr. Aron S. Buchman, an associate professor in the department of neurological sciences at Rush University Medical Center in Chicago.
"This is important as we try to wrap our heads around the biology of aging," he added. "Because it turns out that as you get older Alzheimer's pathology, signs of its development are really ubiquitous, even if that doesn't mean that you actually have dementia. So, this finding could alter the way most medical and non-medical people conceptualize Alzheimer's -- as a disease simply of impaired memory and cognition -- while expanding our view of what it actually means to become frail."
Buchman and his colleagues were expected to publish their findings in the Aug. 12 issue of Neurology.
Prior studies have indicated that about 7 percent of men and women over the age of 65 are frail, meaning they display a significant loss of strength, energy, and agility. That figure rises to 45 percent among people over the age of 85, the researchers said.
In the new study, the Chicago group looked for the presence of the microscopic protein "plaques and tangles" typically associated with Alzheimer's disease in the autopsied brains of 165 male and female study participants.
The autopsies were conducted on Rush patients who had participated in a larger aging and chronic disease study, launched with support from the U.S. National Institute on Aging in 1997. At the time of their deaths, the participants were an average of 88 years old.
While alive, all of the participants had been subject to annual clinical evaluations to assess four markers of frailty: grip strength, time it took to walk eight feet, body mass index (a measure of obesity), and fatigue.
According to the team, patients whose brains showed high levels of Alzheimer's development had been about twice as physically frail as those with low levels of Alzheimer's progression. This was true regardless of whether the patient had experienced dementia or not.
A little more than one-third of the patients had displayed signs of dementia or memory loss prior to their death, the authors noted.
The findings also held up regardless of a patient's physical activity level or disease history.
According to Buchman's group, one previous study that focused on the same group of patients while they were still alive revealed that among those with no cognitive impairment, frailer patients had a higher risk for developing Alzheimer's than those who were less frail.
"So now, we put all this together, and it raises the possibility that Alzheimer's is much more of a public health issue than previously thought, if it turns out that being weak is a sign of its onset," said Buchman. "But, if so, we also now have a clue as to how we can possibly intervene, perhaps by treating motor dysfunction years before people develop dementia, so that they won't develop dementia as early."
Dr. Laurel Coleman, an Augusta, Maine-based geriatrician and member of the Alzheimer's Association's National Board, described the study as "well-done" and "incredibly provocative."
"This study really ties together two very common syndromes in aging --cognitive processes and motor skills -- in ways I have not seen them connected before," she noted. "So, I think this is very important and relevant, because it raises the question of whether frailty could be an early manifestation of Alzheimer's disease. The study doesn't necessarily answer the question, and this is something they now have to go about proving. But already, for me, that idea is a whole new thought that will push me to look at my patients with new eyes."
For more on the warning signs of Alzheimer's, visit the Alzheimer's Association.
Posted: August 2008