Researchers identified a "neural workaround" that compensates for the buildup of a destructive protein linked to Alzheimer's disease.
The findings could help explain how some older adults with beta-amyloid deposits in their brains retain normal cognitive function while others develop dementia, UC Berkeley reported.
"This study provides evidence that there is plasticity or compensation ability in the aging brain that appears to be beneficial, even in the face of beta-amyloid accumulation," said study principal investigator Dr. William Jagust, a professor with joint appointments at UC Berkeley's Helen Wills Neuroscience Institute, the School of Public Health and Lawrence Berkeley National Laboratory.
Past studies have shown a link between increased brain activity and beta-amyloid deposits, but until now it had not been linked to better mental performance.
To make their findings the researchers looked at 22 healthy young adults and 49 older adults who had no signs of mental decline. Brain scans revealed 16 older subjects had beta-amyloid deposits while the rest did not.
The team used functional magnetic resonance imaging (fMRI) to track brain activity while the subjects memorized pictures of various scenes. Afterwards the subjects were tested on their "gist memory" by asking them to confirm if written description of details of the scene were true.
"Generally, the groups performed equally well in the tasks, but it turned out that for people with beta-amyloid deposits in the brain, the more detailed and complex their memory, the more brain activity there was," said Jagust. "It seems that their brain has found a way to compensate for the presence of the proteins associated with Alzheimer's."
The researchers are still unsure why some people with beta-amyloid deposits are better at using different parts of their brains than others. Past studies have shown people who participate in mentally stimulating activities throughout their lives have lower levels of beta-amyloid.
"I think it's very possible that people who spend a lifetime involved in cognitively stimulating activity have brains that are better able to adapt to potential damage," said Jagust.
The findings were published Sept. 14 in the journal Nature Neuroscience
