Talk with an Alzheimer’s researcher and you’ll likely hear the same lament: Finding a treatment or cure is incredibly challenging because scientists are not even certain what exactly causes the neurological disease in the first place.

In fact, researchers speak of a “web of causation” that can lead to Alzheimer’s. In addition to genetics, scientists look to so-called lifestyle elements such as blood pressure and blood sugar levels. Even the bacteria that live in our mouths are being scrutinized for their potential role in Alzheimer’s.

One element that researchers are completely certain about is that people who carry the apolipoprotein E4 gene — known as APOE4 — are at a greater risk of developing Alzheimer’s.