PITTSBURGH — Physical activity boosts the volume of key parts of the brain used in cognitive functioning, according to new research findings that add to the literature suggesting such exertion is among the factors that can reduce likelihood of Alzheimer’s disease.

University of Pittsburgh researchers collaborated with peers from UCLA Medical Center in analyzing data from 876 adults followed long-term at four sites in the late 20th and early 21st centuries. Brain scans that had been done in 1992 and 1998 were matched with the participants’ self-reporting of wide-ranging types of physical activity and estimates of the number of calories those activities burned.

The more calories burned regularly by participants in the 30-year Cardiovascular Health Study — whether exercise, gardening, dancing or any other activity — the more likely that multiple parts of their brain showed up with greater gray matter volume when examined at an average age of 78, according to findings being published this week in the Journal of Alzheimer’s Disease.

In particular, 326 Pittsburgh participants were analyzed for their rate within five years of developing Alzheimer’s or a lesser memory decline known as mild cognitive impairment. Those who retained the most volume in the precuneus, hippocampus and orbital frontal cortex areas of the brain also retained the best cognitive functioning, reducing their likelihood of Alzheimer’s by about half.

The findings are part of a growing focus in Alzheimer’s research on lifestyle choices useful against the disease, considering no drugs have been developed to prevent it.

Neuropsychologist James T. Becker was among a team at Pitt who worked on the study led by former Pitt student Cyrus A. Raji, now a UCLA Medical Center radiologist. Becker noted that mental activity, socialization and healthy eating choices are among other lifestyle factors thought to play a role in reducing Alzheimer’s risk, though it’s been hard to parse the exact value of each compared to the others.

“Physical activity is easier to measure,” Becker said of the proliferation of studies supporting a connection between exercise and cognitive functioning, “but I don’t think anybody has come out and said this is more important than that.”

He said the new study supported earlier suggestions that significant cognitive benefits fall to the 25 percent most vigorous people rather then everyone engaging in physical activity. Even if people showed some cognitive decline among people in that top 25 percent, due to exercise “your brain is not as bad off as it might otherwise have been,” Becker said.