Forgetting the name of a loved one may be one of the first signs people notice of dementia, but it’s rarely the first warning sign your brain gives. Changes in the brain that lead to neurodegenerative diseases like Alzheimer’s and dementia start showing up decades before symptoms arrive, and the chemicals at work inside the body can often tip us off to these changes well ahead of time.

Protein biomarkers have gained significant attention in recent years as potential tools for diagnosing Alzheimer’s and other dementia disorders. A major study examined the proteome, the full set of proteins in the blood, and found that disruptions in proteins associated with metabolism, synaptic communication and the immune system were measurable as early as 20 years before diagnosis.