For years, scientists have searched for a way to predict exactly when Alzheimer’s disease will begin causing memory loss.
A new study suggests that tiny genetic molecules circulating in the blood may finally provide that answer.
The research, published in Nature Medicine, found that circular RNAs could become one of the most useful tools yet for predicting the start of Alzheimer’s symptoms.
One of the biggest challenges in Alzheimer’s disease is that the brain begins changing long before people notice memory problems. Harmful amyloid plaques slowly accumulate over many years. Today’s blood tests can detect these plaques very early, but they cannot tell doctors whether symptoms will begin next year or twenty years later.
Researchers wanted to find a marker that changes closer to the time when the disease actually becomes noticeable. They focused on circular RNAs, unusual pieces of RNA that form closed loops instead of straight strands. These molecules appear to change more quickly than amyloid proteins and may better reflect ongoing brain activity.
The scientists analyzed blood samples from more than 1,200 volunteers. They discovered 34 circular RNAs that were strongly associated with Alzheimer’s disease. Their prediction model performed about as well as the widely used pTau217 blood test when identifying Alzheimer’s pathology.
More importantly, the circular RNA model provided much better information about the future. Elevated levels of these RNAs were linked to almost three times the risk of developing Alzheimer’s symptoms. The changes appeared roughly two to four years before cognitive decline became obvious, giving doctors a potential window for earlier intervention.
Earlier prediction could have major benefits. Many experimental Alzheimer’s treatments are believed to work best before extensive brain damage occurs. Knowing who is close to developing symptoms would help doctors begin treatment at the most appropriate time and would also improve the design of clinical trials by enrolling participants at similar disease stages.
The researchers also point out that modern drugs can remove amyloid from the brain, making some traditional biomarkers appear normal even though the disease continues. Circular RNAs may provide additional information about ongoing disease activity that current tests cannot capture.
The team is now developing clinical laboratory tests that could eventually bring this technology into hospitals. More research is still required before doctors can use these tests routinely, but the early findings are highly encouraging.
This study represents an important advance because it focuses on predicting when Alzheimer’s symptoms will begin rather than simply detecting the disease.
The large sample size and validation across independent groups strengthen confidence in the findings. Nevertheless, the work remains at the research stage, and future prospective clinical studies will be needed before circRNA blood tests become part of standard patient care.
If you care about Alzheimer’s disease, please read studies about the protective power of dietary antioxidants against Alzheimer’s, and eating habits linked to higher Alzheimer’s risk.
For more health information, please see recent studies that oral cannabis extract may help reduce Alzheimer’s symptoms, and Vitamin E may help prevent Parkinson’s disease.
Source: Washington University School of Medicine in St. Louis.
