July 15, 2016 -- Midlife memory lapses may reflect a shift in how your brain forms and retrieves memories, not a decline in thinking skills, a new study suggests.
Researchers at the Douglas Brain Imaging Centre of McGill University in Montreal found that during a memory-related task, a brain region known as the visual cortex was more active in young adults than in middle-aged and older adults. The visual cortex receives information from the eyes.
In middle-aged and older adults, the prefrontal cortex was more active. It plays a role in emotions and behaviors.
"When you meet someone for the first time, it is likely that young adults are paying attention to where and when they met this person, and they can remember this information," says researcher Natasha Rajah, PhD, director of the Douglas Brain Imaging Centre.
"But middle-aged and older adults focus more on the social-emotional relevance of the person they met -- were they pleasant, whether they reminded them of other people they know, and so on -- and this change in focus negatively impacts their ability to remember more objective features," Rajah says.
The study was published online June 12 in the journal NeuroImage.
What's Normal, What's Not?
Many studies have shown that brain changes associated with dementia begin decades before the symptoms appear. So researchers want to know which changes are normal and which are not.
"We know little about what happens at midlife in healthy aging and how this relates to findings in late life. Our research was aimed at addressing this issue," Rajah says in a statement.
For the study, the researchers recruited 112 adults aged 19 to 76. The adults had no history of neurologic or psychological illness and no family history of Alzheimer's disease.
During the study, the adults took several tests on a screen. Then they had to recall where a particular face appeared on the screen -- left or right -- or when it appeared -- most recently or least recently. Their brains were monitored by a type of scan called an fMRI.
The scans were then analyzed to identify which areas of the brain were active during that recall.
Mindfulness May Help
The results showed that the visual cortex was active in young adults as they completed the recall task.
"This suggests that young adults are really paying attention to perceptual details to make their decisions," Rajah says.
Middle-aged and older people had more activity in other brain regions, which are involved in processing information that has more to do with introspective activity.
In other words, the scans may reflect a difference in what adults judge to be important information as they age, Rajah says.
Mindfulness may improve recall in older adults, because it teaches people to be "present in the moment" and to attend to the objective nature of the experience instead of their own inner world, Rajah says.