(CBS) - Most grandmothers say there is no pleasure that quite compares to spending time with your offspring's little ones. And now, a new study finds grandchildren don't only add joy to grandma's golden years. The kids may also keep her mentally sharp.
The study, published in Menopause, the journal of the North American Menopause Society, finds post-menopausal women who spend time taking care of grandkids lower their risk of developing Alzheimer's disease and other cognitive disorders. However, too much time with the grandchildren -- five or more days a week -- appeared to make grandma more likely to lose her marbles.
For the study, researchers for the Women's Health Aging Project in Australia, administered three different tests to assess the cognitive abilities of 186 women, ages 57 to 68. Among the group, 120 were grandmothers. The researchers add that 9 percent of the cohort eventually withdrew from the study, claiming they were too busy caring for their family to participate.
Overall, the researchers found the grandmothers who helped with childcare at least one day per week scored highest on the tests, while the women who spent five or more days a week with their grandkids scored significantly lower.
The researchers also found the grandmothers who helped out more often felt their own children -- the parents of the grandkids -- were too demanding of their time. The researchers suggest that feeling overextended dampened the mood of those grandmothers, which impacted brain function.
There's a large body of research that finds regular social interaction can help seniors stay mentally healthier.
One study, published last year in the Proceedings of the National Academy of Sciences, found older women and men who spend too much time apart from family members had a 26 percent higher death risk during a seven year period than those who were more socially-engaged. Some research also finds staying in touch the modern way, such as through Facebook and other forms of social media, can help promote healthy aging.
"The motivation of the present study was to expand on the current literature by examining the impact of grandparenting on cognitive function," the authors write in the new study. "To our knowledge, this is the first study to examine the relationship between grandparenting and cognition."
Next, the researchers say they plan to conduct studies with larger samples of seniors that also examine how other social roles impact cognition in the aging brain.