A small Australian study finds that grandmothers who take care of their grandchildren one day a week do better on cognitive tests than peers who mind grandkids more often, or not at all.

Researchers say the brain benefits from this form of “grandparenting” may come not just from having social engagement, but “active” engagement in those relationships.

“The key point here is they found that the socialization part was important primarily when it was associated with some kind of useful function,” said Dr. William J. Hall, a geriatrician who was not involved in the study.

“The party line on this from geriatricians like me is that some form of social engagement seems to be absolutely essential for maximizing the chances you will have good brain function for those years,” said Hall, who directs the Center for Healthy Aging at the University of Rochester Medical Center in New York.

Study authors Katherine Burn and Cassandra Szoeke, researchers at the University of Melbourne in Parkville, Australia, point out in the journal Maturitas that lifestyle and environmental factors are easy, inexpensive ways of boosting cognitive health and might even help stave off chronic illnesses like dementia and Alzheimer’s disease.

For the new study, they used data from the Women’s Healthy Ageing Project, which Szoeke directs, and which involves Australian women originally recruited for a midlife study in 1991, when they were aged 45 to 55.

The 224 women included in the new analysis were between 65 and 75 and lived in the Melbourne area. Most had grandkids, and most spent time taking care of an average of three grandchildren. Those who did care for grandchildren were about a year younger and more likely to have at least 12 years of formal education than those who didn’t.

The researchers used various tests to gauge the women’s cognitive ability, asking them to read numbers forward and backward, name as many animals, boy’s names and fruit and furniture as they could and to copy a drawing.

To test memory, the women repeated a word list and named as many words as they could beginning with different letters.

After factoring in the women’s age and education levels, the researchers found that those who were caring for grandkids one day per week did better on the cognitive tests than those who weren’t minding grandkids, or those who were caring for grandkids up to five days a week.

“We wanted to be able to guide people on a common, in fact the most popular informal childcare option prevalent in our community,” Szoeke said in an email. “The aspects of social engagement hypothesized to be responsible for the benefits on cognition (positive mood, mental stimulation, increased activity) were highly relevant to activity as a grandparent.”

But more research is needed on the benefits of social engagement to cognition in general, and especially on the role grandparenting could play in its maintenance, the authors note.

The study did not account for health or economic factors that might affect the women’s cognitive function, as well as possibly influencing whether or how often they cared for their grandchildren.

The authors acknowledge that their results suggest a connection between some amount of grandparenting and better mental function, but cannot prove cause and effect.

Hall said that he wasn’t sure if the results would apply to the United States, where the pace is faster and the quality of life less “tranquil” than in Melbourne. But he said he thought the information should prove useful to older people.

“In the field of geriatrics and gerontology, this whole idea of social engagement and what kind of social engagement goes forward is extremely hot right now,” said Hall. “This is better than treating people with pills.