Researchers from the University of California, Davis, have found that a small “wishbone-shaped structure” in the brain can provide early clues about potential cognitive decline before symptoms of memory loss or dementia present themselves.
The fornix is a bundle of fibers – also known as axons – in the brain that carries messages to and from the hippocampus, also playing a part in memory.
But the researchers, led by scientist Even Fletcher of the UC Davis Alzheimer’s Disease Center, discovered that the only perceivable brain differences between healthy people who develop cognitive decline and those who do not lies in changes to the fornix. The results of their study were published in JAMA Neurology.
The research involved 5 years and a group of 102 healthy people who were at an average age of 73 and who did not exhibit any symptoms of cognitive decline.
Credit: UC Regents
Magnetic resonance imaging (MRI) analysis of the participants’ brains was conducted, cataloguing the volume and integrity. Additionally, a different MRI was used to analyze the myelin, the fatty coating that protects the fibers of the fornix. The researchers describe the fibers as “the copper wiring of the brain’s circuitry,” while the myelin is like the wiring’s “plastic insulation.”
In addition to undergoing cognitive evaluations and psychological tests, the participants returned each year for updated MRIs and testing.
During the course of the study, about 20% of the participants showed symptoms for mild cognitive impairment (MCI) or Alzheimer’s disease, and two fornix characteristics were shown to predict this cognitive impairment: low fornix white matter volume and reduced axonal integrity.
“We found that if you looked at various brain factors there was one – and only one – that seemed to be predictive of whether a person would have cognitive decline, and that was the degradation of the fornix,” Fletcher says.
The study’s authors note that changes within the hippocampus present themselves during the later stages of cognitive decline, and these changes are thus the most studied for Alzheimer’s research. Studying changes to the fornix has not been closely examined until now.
Because the changes within the fornix presented themselves much earlier than changes in the hippocampus, Fletcher notes that “this could be a very early and useful maker for future incipient decline.”
In the future, Fletcher says that routine MRI examinations of the fornix could be used clinically to predict cognitive decline:
“Our findings suggest that if your fornix volume or integrity is within a certain range, you’re at an increased risk of cognitive impairment down the road. But developing the use of the fornix as a predictor in a clinical setting will take some time, in the same way that it took time for evaluation of cholesterol levels to be used to predict future heart disease.”
The key finding of the study, according to the researchers, is that white matter, rather than gray matter measures, may be promising markers for predicting cognitive decline.
Medical News Today recently reported about a video game that could combat cognitive decline.