If you know a loved one with Alzheimer’s disease, chances are good he or she won’t get cancer, says new research published in the journal Neurology. Turns out the reverse also is true.

Researchers studied about three-thousand people older than sixty-five, evaluating their cognitive abilities and tracking them for several years. Those with Alzheimer’s disease at the start of the study were less likely to be diagnosed with cancer by the study’s end. Similarly, people diagnosed with cancer before the study began were less likely to develop Alzheimer’s disease.

The reasons for this association are still unknown, but other scientists have found similar links between Parkinson’s disease and cancer. Some suspect neurological pathways affecting the lifecycles of cells could explain the relationship, but more study is needed to know for sure.

White participants who started the study with no cancer history were about four times more likely to have Alzheimer’s disease at the end of the study than those with a history of cancer at the study’s onset. The number of minority participants with cancer at the start of the study was too small to allow meaningful conclusions based on that information.

The negative association between Alzheimer’s disease and cancer remained significant, even when the researchers took into account factors such as smoking, obesity, exercise and demographics.

According to the Centers for Disease Control and Prevention, Alzheimer’s disease ranks sixth among the top causes of death among adult Americans, and the number of people who die from the disease yearly is growing. In contrast, rates of cancer and heart disease deaths are decreasing.