Call it good news/bad news: What looks like Alzheimer's disease might not be Alzheimer's at all. But it is a form of dementia that's been overlooked until now, Quartz reports. New research published in Brain has identified LATE, or limbic-predominant age-related TDP-43 encephalopathy, a memory-eroding disease that usually moves slower than Alzheimer's and appears only after age 80. It may also be more common than Alzheimer's for that age group and makes decline worse when the two diseases exist together, CNN reports. But their effect on the brain is quite different: "These age-related dementia diseases are frequently associated with proteinaceous glop," says lead study author Peter Nelson. "But different proteins can contribute to the glop."
The glops in Alzheimer's brains are oddly shaped amyloid plaques and clumps of proteins called tau; in LATE, they're TDP-43 proteins. Doctors don't know why they become misshapen, but they're working on it—and say the find is part of separating Alzheimer's from other forms of dementia and preventing misdiagnosis. "More than 200 different viruses can cause the common cold," Nelson tells Psych Central. "So why would we think there is just one cause of dementia?" The goal now, he says, is to develop LATE-specific treatments that might reveal why many Alzheimer's drugs have failed in clinical trials. Until then, we're grappling with a disease that "has an expanding but under-recognized impact on public health," per the study. (Read more dementia stories.)