A new test may be able to diagnose Alzheimer’s disease in its early stages — before any dementia symptoms surface.

Researchers today say they’ve discovered a test that’s been proven highly accurate in predicting which patients have early memory problems and other symptoms of cognitive decline that could eventually lead to Alzheimer’s, Reuters reports.

Scientists at the University of Pennsylvania School of Medicine analyzed 410 patients. The test measured the amount of certain proteins in the spinal cord. Patients with low levels of the amyloid beta-42 polypeptide protein were more likely to develop the disease — presumably because the protein was, instead, accumulating in the brain and causing plaque buildup. These plaques help destroy healthy neurons and lead to memory impairments and more.

The study also revealed that people with high levels of the tau protein in their spinal fluid were more likely to develop the disease. Lead researcher Leslie Shaw believes the high tau levels are a result of dying nerve cells. The researchers say the test proved to be 87 percent accurate.

Almost five million people in the United States suffer from the irreversible brain disease, according to statistics released by the National Institute of Health. Having an early diagnosis of Alzheimer’s and starting treatment in the early stages can help slow the decline.

The study is available in the journal Annals of Neurology.

Click here for the full Reuters report.