FILE - Alzheimer's disease patient Isidora Tomaz, 82, sits in an armchair in her house in Lisbon, Portugal, Sept.15, 2009.
FILE - Alzheimer's disease patient Isidora Tomaz, 82, sits in an armchair in her house in Lisbon, Portugal, Sept.15, 2009.

WASHINGTON - As populations continue to age, more and more people are going to begin to experience mild cognitive impairment, a precursor to Alzheimer’s disease.  It’s predicted that by 2050, 135 million Americans are going to suffer from mild cognitive impairment, or MCI. But the results of a new study in Australia show that increased muscle strength can improve brain function in older adults.

In mild cognitive impairment, people have noticeably reduced memory but are able to lead otherwise normal lives.

In the Australian study, investigators showed that exercise in the form of progressive resistance training improved brain function in those over the age of 55.

In the study, called the Study of Mental and Resistance training or SMART, 100 adults with MCI, between the ages of 55 and 86, were divided into four groups.

One group received lessons in resistance exercise and computerized cognitive training, another group was given resistance training but got placebo computerized training. Still another group received brain training but went through a fake exercise routine and a final group was given fakes in both exercise and cognitive training.

Researchers wanted to see whether there was a positive link between muscle strengthening and brain functioning.

Resistance training included weight lifting sessions with gradually increased weights over time.   Those who were able to lift weights to an intensity of 80 percent of their peak strength had the greatest improvement in cognitive function as measured by an Alzheimer’s disease assessment scale.  The benefits endured even a year after the supervised strength training exercises stopped.

The findings were published in the Journal of American Geriatrics.

Researchers say the key is for older adults to do resistance strength training, like lifting weights, at least two times per week.

The findings confirm earlier studies this year on MRI that showed increases in the size of particular brain regions associated with improvements in cognitive training among the weight lifters.

It could be that resistance exercise may be prescribed as a way to stave off cognitive impairment once the researchers confirm a link between muscle strength training and improved cognition in older patients.