AD comes in two forms, early-onset or late-onset, and both produce a range of symptoms from mild to severe (NIA, 2019a). At first, the disease may just manifest in ways that only the person or loved ones may notice – repeating questions, getting lost, putting stuff in odd places (e.g., keys in the fridge), etc. As the disease progresses, cognitive ability gets worse. People may no longer recognize loved ones, hallucinate, and have difficulty carrying out everyday tasks. In the most severe form, the disease essentially erases the person mentally and severs the person’s control of their body. Often towards the end, they lose the ability to swallow, leading to pneumonia and death.
What exactly is happening to the brain that could ultimately erase a person? In a nutshell, the brain is shrinking – considerably. The science is not entirely clear about what is exactly happening, but the data suggests two proteins, amyloid and tau, are at the epicenter (NIA, 2019b). Proteins start to form “plaques” and “tangles,” eventually cutting off neurons from one another. Separated, the cells die, which contributes to the shrinkage and erasure.
The shrinkage does not happen instantaneously, but rather over years to decades. Current methods to diagnose AD include spinal taps, MRI or PET imaging, but may not be sensitive enough to catch early stages or to stratify patients in an optimal way to truly benefit clinical trials of promising treatments (Shi et al., 2019).
Looking at changes in our proteins might be another approach worth trying. In a study with the largest sample size known to date surveying the most proteins possible, a team of researchers went looking for new insights (Shi et al., 2019). Although their work is preliminary, proteomics appears to deliver both better understanding the biology and improvement in ways to treat AD. In their study, they identified ten molecular pathways as markedly changed in AD patients, including some already suspected. Furthermore, the inclusion of protein data improved AD vs. non-AD patient sorting over just using genetic information and age.
A test that can screen accurately for AD and do so better than current tests would be a huge step forward for diagnosing the disease, maybe even pre-symptomatically. At that point, the question becomes: If such a test existed, would you take it? The answer depends, in part, on how soon effective treatments can be found. Perhaps using these same findings will get us there faster too.
National Institute of Aging (NIA) (2019a). What Are the Signs of Alzheimer’s Disease? Retrieved on September 10, 2019 from https://www.nia.nih.gov/health/what-are-signs-alzheimers-disease.
National Institute of Aging (NIA) (2019b). Video: How Alzheimer’s Changes the Brain. Retrieved on September 17, 2019 from https://www.nia.nih.gov/health/video-how-alzheimers-changes-brain?utm_source=ADvideo&utm_medium=web&utm_campaign=rightrail.
Shi, L., Westwood, S., Baird, A. L., Winchester, L., Dobricic, V., Kilpert, F., . . . Nevado-Holgado, A. J. (2019). Discovery and validation of plasma proteomic biomarkers relating to brain amyloid burden by SOMAscan assay. Alzheimers Dement. doi:10.1016/j.jalz.2019.06.4951