Older people might be able to help ward off Alzheimer's disease and dementia with a little weightlifting, suggest the findings of a new study in the Archives of Neurology.
The study found that the greater a person's muscle strength, the lower their likelihood of either being diagnosed with Alzheimer's, or experiencing the loss of mental function that often precedes Alzheimer's.
Previous research has linked a person's weight and level of physical activity to Alzheimer's. But until now, no one has studied whether muscle strength in and of itself might be linked to dementia risk.
So Dr. Patricia A. Boyle of Rush Alzheimer's Disease Center in Chicago led a team to study 970 dementia-free men and women aged 54 to 100 years old.
They analyzed the volunteers' physical strength by measuring strength of nine muscle groups in the arms and legs in the volunteers, and also tested the strength of their breathing muscles. They then followed the volunteers for about four years, to see who developed dementia.
During the study period, 138 people developed Alzheimer's, while an additional 275 experienced mild mental difficulties. Not surprisingly, these individuals were older. But they also had worse mental function than the rest of the study participants -- and were physically weaker.
Even after the researchers adjusted for age and education level -- which can affect Alzheimer's risk -- muscle strength still had a strong influence on the risk of dementia.
People in the top 10 per cent for muscle strength were 61 per cent less likely to develop Alzheimer's than the weakest 10 per cent. People who were stronger at the beginning of the study also experienced a slower rate of mental decline.
The researchers noticed a relationship between muscle strength and milder dementia, as well. The strongest 10 per cent were at 48 per cent lower risk of mild mental difficulties than the weakest 10 per cent.
When the researchers looked at different types of muscle strength separately, they found that hand grip strength and breathing-muscle strength had the most effect on Alzheimer's risk, but arm and leg strength didn't.
The researchers don't think that weak muscles cause Alzheimer's. They suspect, instead, that there is something going in the body that causes both muscle weakness and loss of mental ability.
It's possible that damage to the mitochondria, which produce energy inside the body's cells, may contribute to both the loss of both muscle strength and the loss of cognitive function.
