Years of study into the Alzheimer’s biomarker named beta-amyloid have yielded few notable results for an earlier diagnosis and drug treatment. As one alternative, Alzheimer’s researchers have been chasing a lead that glucose levels in the brain may hold the key to an early biomarker of the neurodegenerative disease.
To date, changes in glucose levels have been measured with PET scans, which are expensive and carry side effects. They require scientists to inject patients with radioactive tracers. But now, researchers have made new headway in the study of glucose — this time using MRIs.
In the recent study published in Science Advances, the team monitored changes in the brain’s glucose level with an MRI imaging technique using natural sugars. Not only is MRI a less invasive method, it is more widely available in hospitals.
Using this technique, they found that glucose was cleared from the glymphatic system much slower in mice with Alzheimer’s, especially younger mice.
“At this age group, they don’t have many plaques [of beta-amyloid] in the brain. This could be an imaging biomarker to indicate that this is an early stage of Alzheimer’s disease,” said Dr. Kannie Chan Wai-yan, an author of the study and an associate professor at City University of Hong Kong’s department of biomedical engineering.
“What are the physiological processes that lead to this slow down? We have research still underway to understand more about the cause of this significant decrease,” Chan said.
The glymphatic system is still a new area of research as scientists first described it in 2012. Its name was coined by Danish neuroscientist Maiken Nedergaard in reference to the glial cells that regulate the flow of cerebrospinal fluid.
The system is like a series of pipes piggybacking on the brain’s blood vessels, allowing cerebrospinal fluid to flow through brain tissues and clearing waste from the brain, similar to the body’s lymphatic system.
The latest findings add to the wave of research in the glymphatic system since its recent discovery. Scientists found that the system was most busy when animals slept, speeding up the removal of beta-amyloid.
It also becomes dramatically less effective as the brain ages. The system may render us more vulnerable to neurodegenerative diseases, speeding up the progression of cognitive dysfunction.
Comorbidities of Alzheimer’s are also linked to the glymphatic system. Scientists found that rats with type 2 diabetes, a condition that may increase the risk of dementia by about 60 percent, are more likely to have impaired glymphatic systems. High blood pressure may also impair the system’s function, preventing the system from getting rid of molecules in the brain such as beta-amyloid.
Chan hopes to begin human clinical trials in about three years. Meanwhile, the team has forged ahead and begun a human pilot trial to fine-tune their imaging technique.
