When it comes to parts of your brain, bigger isn't necessarily better. Experts long believed that a bigger hippocampus meant better memory. But new research finds that the size of this seahorse-shaped structure deep in the brain doesn't always predict learning and memory abilities.
Markers of memory decline
Researchers looked at more than 330 older adults in Germany and found that a larger hippocampus is only an advantage in people who also have more white-matter circuitry intact to link the hippocampus to the rest of the brain.
"Our findings highlight the need to measure not just the size of the hippocampus but also how well it's connected to the rest of the brain when we look for physical markers of memory decline in older adults," said study lead author Andrew Bender. He's an assistant professor of epidemiology and biostatistics in Michigan State University's College of Human Medicine.
It's normal for the hippocampus to shrink as we age, but this loss is greater in people with mildly impaired thinking or Alzheimer's disease.
The researchers said this study could help lead to earlier diagnosis of such age-related memory disorders.
Mental decline in some older adults whose brain scans show a larger hippocampus could be missed if doctors don't also consider their white-matter connectivity, researchers explained.
Change in older adults' brain structure
"Our findings reinforce a growing perspective that studying age-related changes in learning and memory from a systems perspective appears far more informative in understanding different patterns of brain and cognitive declines than focusing on any single brain region," Bender said in a university news release.
His team will continue to track study participants.
"By following people over time," Bender said, "we can see if there is actually change in older adults' brain structure and whether that is linked with observable declines in learning and memory."
The study was recently published online in the journal Cerebral Cortex.
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