July 7 (UPI) -- Physical activity may lead to positive changes in brain tissue that help stave off cognitive decline in older adults, a study published Wednesday by the journal PLOS ONE found.
These changes are visible on magnetic resonance imaging, which means physicians can measure the effects of exercise on the aging brain, the researchers said.
Participants who led more active lifestyles as they aged showed improved cognitive function based on several measures.
In addition, MRIs performed after participants died indicated that those with more active lifestyles had evidence of less tissue damage to the white matter.
However, those who led less active lifestyles as they grew older did not perform as well on cognitive tests and had signs of white matter tissue damage on MRIs, the researchers said.
"We were able to use MRI to see that many older adults who were not very active had incurred certain types of damage to the brain [and] this damage, in turn, was often linked with poorer cognitive function," study co-author Robert Dawe told UPI in an email.
"Therefore, safely engaging in physical activity might be one way that older adults can keep their brains healthy and protect against cognitive decline," said Dawe, an assistant professor at the Rush University Alzheimer's Disease Center in Chicago.
The findings are based on MRI scans of 318 older adults performed after death, according to Dawe and his colleagues. Study participants died at an average of 91 and had agreed to donate their brains for examination.
Before their death, participants had their levels of physical activity measured over a period ranging from five to 15 years with a wearable accelerometer, which measures body movement.
In addition, participants' cognitive function was assessed annually over this same period, including tests for memory, balance and brain processing speed.
Participants who were more active based on accelerometer readings performed better on these cognitive tests over the course of the study.
Recent research has suggested that lifestyle choices -- including eating a healthier diet, consuming less alcohol and engaging in regular physical activities -- have an impact on brain health in older adults.
This study is among the first to document the brain changes linked with physical activity and show that these changes can be measured using MRI, the researchers said.
"The general public seems to be increasingly aware that lifestyle factors that are good for the heart, like physical activity, are generally good for the brain and cognition, as well," Dawe said.
"[We don't know] exactly why people with lower levels of physical activity frequently had this type of damage to the tissue, [but] many researchers suspect that decreased blood flow to the brain is to blame," he said.