A blood test for dementia may tell you if you have more than one type

The experimental test could help doctors spot overlapping brain diseases

A vial of blood and brain scans for dementia in the background

The test can help diagnose four neurodegenerative diseases — Alzheimer's, Parkinson's, frontotemporal dementia and dementia with Lewy bodies — based on levels of 15 proteins in the blood.

Andrew Brookes/Connect Images/Getty Images

When something goes wrong in the brain of people with dementia, often it’s more than one thing.