Scientists have found a blood test-like method that can detect a specific brain problem called Lewy body pathology in people with Alzheimer’s, and it’s accurate over 96% of the time — meaning it could help doctors spot this common brain issue without needing an autopsy.

We analyzed the available evidence and found that a test using cerebrospinal fluid can detect Lewy body pathology in people with Alzheimer’s with high accuracy—over 96% of the time [1]. This test works by identifying tiny, misfolded proteins that spread in the brain, similar to how a seed grows into a plant, which is why it’s called a seed amplification assay. It’s not a blood test, but it does offer a way to detect this brain change without needing an autopsy after death. What we’ve found so far is that all the evidence reviewed supports the idea that this method is highly accurate in identifying Lewy body pathology in individuals already diagnosed with Alzheimer’s. There are no studies in our review that contradict this finding. The test appears to pick up on the presence of these abnormal proteins with very few errors, which could help doctors better understand what’s happening in a patient’s brain during life, rather than only after death. Lewy body pathology refers to clumps of a protein called alpha-synuclein that can interfere with brain function and are often found alongside the plaques and tangles typical of Alzheimer’s. When both are present, symptoms can be more complex. Knowing whether Lewy bodies are there may help tailor care, even if it doesn’t change the overall diagnosis. The evidence we’ve reviewed suggests this assay is a promising tool, but it’s still used mostly in research settings. It requires a spinal tap to collect cerebrospinal fluid, which is more involved than a blood draw. We don’t yet know how widely available or practical it is outside specialized clinics. For now, if you or someone you know has Alzheimer’s and symptoms that seem unusual—like hallucinations or movement problems—this test might offer clearer insight into what’s happening in the brain. But it’s not something most doctors order routinely yet.