“The loss of fMRI signal means there is less blood flow to the region, but we believe the underlying basis for this loss has to do with the fact that the structural integrity of that part of the brain is changing,” Yassa said. “One of the things we know about Alzheimer’s disease is that this region of the brain is one of the very first to exhibit a key hallmark of the disease, deposition of neurofibrillary tangles.”

In contrast, the researchers did not find age-related differences in another area of the brain connected to memory, the posteromedial entorhinal cortex. They demonstrated that this region plays a role in spatial memory, which was not significantly impaired in the older subjects.


“This suggests that the brain aging process is selective,” Yassa said. “Our findings are not a reflection of general brain aging but rather of specific neural changes that are linked to specific problems in object but not spatial memory.”

To determine whether this type of fMRI scan could eventually be used as a tool for early diagnosis, the researchers plan to expand their work to a sample of 150 older adults who will be followed over time. They will also be conducting positron emission tomography, or PET, scans to look for amyloid and tau pathology in their brains as they age.

“We hope this comprehensive imaging and cognitive testing will enable us to figure out whether the deficits we saw in the current study are indicative of what is later to come in some of these individuals,” Yassa said.

“Our results, as well as similar results from other labs, point to a need for carefully designed tasks and paradigms that can reveal different functions in key areas of the brain and different vulnerabilities to the aging process,” Reagh added.

This study was supported by the National Institutes of Health’s National Institute on Aging (grants P50AG05146, R21AG049220 and R01AG053555), a National Science Foundation Graduate Research Fellowship, and fellowships from the UCI Chancellor’s Club and the ARCS and Roche foundations.

About the University of California, Irvine: Founded in 1965, UCI is the youngest member of the prestigious Association of American Universities. The campus has produced three Nobel laureates and is known for its academic achievement, premier research, innovation and anteater mascot. Led by Chancellor Howard Gillman, UCI has more than 30,000 students and offers 192 degree programs. It’s located in one of the world’s safest and most economically vibrant communities and is Orange County’s second-largest employer, contributing $5 billion annually to the local economy.

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