FRIDAY, Jan. 18, 2019 (HealthDay News) -- Frailty is associated with a higher risk of both Alzheimer's disease and its crippling symptoms, a new study shows.
"By reducing an individual's physiological reserve, frailty could trigger the clinical expression of dementia when it might remain asymptomatic in someone who is not frail," said study leader Dr. Kenneth Rockwood, a professor at Dalhousie University in Halifax, Canada.
"This indicates that a 'frail brain' might be more susceptible to neurological problems like dementia as it is less able to cope with the pathological burden," he added.
The study included 456 adults in Illinois, aged 59 and older, who did not have Alzheimer's when first enrolled in the Rush Memory and Aging Project. They underwent annual assessments of their mental and physical health, and their brains were examined after they died.
By their last assessment, 53 percent of the participants had been diagnosed with possible or probable Alzheimer's disease.
For the physical assessments, the researchers created a frailty index using 41 components, including fatigue, joint and heart problems, osteoporosis, mobility and meal preparation abilities.
Overall, 8 percent of the participants had significant Alzheimer's disease-related brain changes without having been diagnosed with dementia, and 11 percent had Alzheimer's but little evidence of disease-related brain changes.
Those with higher levels of frailty were more likely to have both Alzheimer's disease-related brain changes and symptoms of dementia, while others with substantial brain changes, but who were not frail, had fewer symptoms of the disease.
After adjusting for age, sex and education, the researchers concluded that frailty and Alzheimer's disease-related brain changes independently contribute to dementia, though they could not prove that frailty caused Alzheimer's and its symptoms.
The investigators also said there was a significant association between frailty and Alzheimer's-related brain changes after they excluded activities of daily living from the frailty index and adjusted for other risk factors such as stroke, heart failure, high blood pressure and diabetes.
The study was published Jan. 17 in The Lancet Neurology journal.
"This is an enormous step in the right direction for Alzheimer's research," Rockwood said in a journal news release. "Our findings suggest that the expression of dementia symptoms results from several causes, and Alzheimer's disease-related brain changes are likely to be only one factor in a whole cascade of events that lead to clinical symptoms."
Understanding frailty could help predict and prevent dementia, Dr. Francesco Panza, from the University of Bari Aldo Moro in Italy, wrote in an accompanying editorial.
The U.S. National Institute on Aging has more about Alzheimer's disease.
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