A glimpse into the future may already be flowing through our veins. In a major breakthrough, researchers have developed a simple blood test that may one day help doctors predict how fast early-onset dementia will progress. “[It] can give us a window into how aggressively the disease is likely to behave — and that’s information that up to now, we really didn’t have,” Dr. Liron Sinvani , director of research and innovation for the Northwell Institute of Healthy Aging Institute, who was not involved in the study, told The Post. A simple blood test could offer clues into the kind of early-onset dementia a person has and the speed of its progression. angellodeco – stock.adobe.com Early signs suggest the test may also offer insight into the type of dementia a person has — something Sinvani called a “game changer” for patients and their loved ones . “When we talk about dementia, most people think of someone in their 80s and 90s, but early-onset dementia strikes people in their 50s and 60s,” she said.…