The study, published in the Journal of Alzheimer's Disease, suggested the link might have to do with certain biological effects of breastfeeding. For example, breastfeeding restores insulin tolerance, which is significantly reduced during pregnancy, and Alzheimer's is characterized by insulin resistance in the brain, the study said.
Study leader Dr. Molly Fox of the Department of Biological Anthropology at the University of Cambridge said although the data gathered was from a very small group of just 81 British women, the researchers observed a highly significant and consistent correlation between breastfeeding and Alzheimer's risk.
Fox said the finding was so strong that any potential sampling error was unlikely.
However, the connection was much less pronounced in women who already had a history of dementia in their family.
The research team said they hoped their preliminary study would stimulate further research looking at the relationship between female reproductive history and disease risk.