I think about Alzheimer’s more than someone my age probably should. But I don’t think I’m alone. There is something uniquely haunting about the disease. Anyone who has watched a loved one disappear—their memories slipping and personality fading—will know how tenaciously the experience stays with you.

For decades, research has made frustratingly little progress towards a cure for Alzheimer’s. Scientists and pharmaceutical companies have mostly chased a single theory, pouring tens of billions of dollars into treatments that, at best, only slow the progression of the disease.

But now a growing number of researchers are exploring a very different idea, that viruses might trigger Alzheimer’s. The theory has exciting implications for treatment. If viruses are the cause it might be possible to treat, or even prevent, the disease using drugs we already have. For future sufferers, and people who think about Alzheimer’s as much as I do, it offers a reason for hope.