Though there are many medical reasons why breastfeeding is widely recommended, researchers at the University of Cambridge have made an unlikely connection through a new study.

The study, published in the Journal of Alzheimer’s Disease, found that breastfeeding could be linked to a reduced risk of Alzheimer’s disease. Researchers interviewed 81 British women between ages 70 and 100, some of whom had Alzheimer’s. They found a “highly significant and consistent correlation” between the women who breast fed and their risk of Alzheimer’s.

In addition, the study found a longer breastfeeding history was linked to lowered risk for Alzheimer’s. Women who had a high ratio of pregnancy time to breastfeeding time, however, were found to have a higher Alzheimer’s risk. The link between Alzheimer’s risk and breastfeeding was found to be “far less pronounced” for women with a family history of Alzheimer’s disease.

Though the cause of the link was not determined by the study, it’s authors have floated multiple theories for why it apparently exists. One involves the hormone progesterone, which has been linked to a desensitization of the brain’s estrogen receptors. The hormone is produced in high amounts during pregnancy, but is reduced by breastfeeding. Another theory is that breastfeeding restores insulin sensitivity that is reduced by pregnancy, increasing glucose tolerance.

“Alzheimer’s is the world’s most common cognitive disorder and it already affects 35.6 million people,” said Molly Fox, lead author of the study and a professor of biological anthropology at Cambridge. “In the future, we expect it to spread most in low and middle-income countries. So it is vital that we develop low-cost, large-scale strategies to protect people against this devastating disease.”