LOS ANGELES, Nov. 10 (Xinhua) -- Seniors with weak muscles are at greater risk of developing Alzheimer's disease, a new study shows.

    Researchers at Rush University Medical Center in Chicago based their study on analysis of 970 older adults with an average age of80, who underwent a number of evaluations, including tests of cognitive function and muscle strength.

    The participants didn't have dementia at the start of the study. During an average 3.6 years of follow-up, 138 (14.2 percent) of the participants developed Alzheimer's disease. Those with the highest levels of muscle strength at the start of the study were 61 percent less likely to develop Alzheimer's than those with the weakest muscles, according to the study.

    The link between muscle strength and Alzheimer's remained even after the researchers accounted for other factors, such as body mass index and physical activity levels, the researchers noted in the study published in the Nov. issue of the Journal Archives of Neurology.

    The researchers also found that weak muscles were associated with increased risk of mild cognitive impairment, the earliest sign of cognitive decline.

    "Overall, these data show that greater muscle strength is associated with a decreased risk of developing Alzheimer's disease and mild cognitive impairment and suggest that a common pathogenesis may underlie loss of muscle strength and cognition in aging," said the study.

    Although the reason for the association between muscle strength and Alzheimer's risk isn't known, the study authors noted that there are a number of possibilities which include:

    -- Damage to the mitochondria, which produce energy for cells, may contribute to loss of both muscle strength and cognitive function; and

    -- Decreased strength could be caused by stroke or other central nervous system disorders that also may reveal subclinical Alzheimer 's disease.