This precise approach “makes it possible to make drugs that only act on the cell type you care about,” reducing the unwanted side effects that most drugs have, says Margus, chief executive officer of Cerevance, a Boston-based drug development company focused on brain diseases. What’s more, it could lead to a major breakthrough in the field of dementia research. About 50 million people worldwide suffer from dementia, and still there is no treatment to stop or slow its progression.