“Imagine a world where diagnosing Alzheimer’s disease is as simple as getting your blood tested during your annual physical,” writes philanthropist Bill Gates. He’s started a venture to fund development of novel biomarkers, which are measurable signs in the brain and body of the presence of disease proteins: amyloid, tau, and α-synuclein, among others. His dream is one shared by all Alzheimer’s and Parkinson’s researchers— to bring these brain conditions into the realm of common diseases such as heart disease and cancer that are routinely caught in the earliest stages and treated before full blown symptoms arise.
Early detection of Alzheimer’s and related diseases poses a uniquely high hurdle. Obviously, it is logistically difficult to obtain, in a living brain, information about abnormal proteins. Instead, researchers must use proxy measures called biomarkers. Ideally, these proxies should be an accurate reflection of the degree of pathology in the brain, reproducible, low cost, and tolerable for most people. No biomarker currently meets these standards. The two most common methods of colecting biomakers are cerebrospinal fluid (CSF) tests and special PET scans. However, obtaining CSF requires a spinal tap; PET scans are less invasive, but they are costly and not widely available. Compared to these tools, blood biomarker tests could be the key to early detection of Alzheimer’s because they can be scaled up for regular use in clinical settings.
