Field Notes

Old, Young Brains Rely on Different Systems to Remember Emotional Content

Neuroscientists from Duke University Medical Center have discovered that older people use their brains differently than younger people when it comes to storing memories, particularly those associated with negative emotions. The study, appearing online in Psychological Science, is a novel look at how brain connections change with age.

Older adults (average age 70) and younger adults (average age 24) were shown a series of 30 photographs while their brains were imaged in a functional MRI (fMRI) machine. Some of the photos were neutral in nature, and others had strong negative content such as attacking snakes, mutilated bodies, and violent acts. While in the fMRI machine, the subjects looked at the photos and ranked them on a pleasantness scale. Then they completed an unexpected recall task following the fMRI scan to determine whether the brain activity that occurred while looking at the pictures could predict later memory. The results were sorted according to the numbers of negative and neutral pictures that were remembered or missed by each group.

The scientists found that older adults have less connectivity between an area of the brain that generates emotions and a region involved in memory and learning. But they also found that the older adults have stronger connections with the frontal cortex, the higher thinking area of the brain that controls these lower order parts of the brain.

Young adults used more of the brain regions typically involved in emotion and recalling memories.

“The younger adults were able to recall more of the negative photos,” says Roberto Cabeza, PhD, senior author and a professor in Duke University’s Center for Cognitive Neuroscience. If the older adults are using more thinking than feeling, “that may be one reason why older adults showed a reduction in memory for pictures with a more negative emotional content.”

“It wasn’t surprising that older people showed a reduction in memory for negative pictures, but it was surprising that the older subjects were using a different system to help them to better encode those pictures they could remember,” says lead author Peggy St. Jacques, a graduate student in the Cabeza laboratory.

The emotional centers of the older subjects were as active as those of younger subjects; it was the brain connections that differed.

“If using the frontal regions to perform a memory task was always beneficial, then the young people would use that strategy, too,” Cabeza says. “Each way of doing a task has some trade-offs. Older people have learned to be less affected by negative information in order to maintain their well-being and emotional state. They may have sacrificed more accurate memory for a negative stimulus, so that they won’t be so affected by it.”

“Perhaps at different stages of life, there are different brain strategies,” Cabeza speculates. “Younger adults might need to keep an accurate memory for both positive and negative information in the world. Older people dwell in a world with a lot of negatives, so perhaps they have learned to reduce the impact of negative information and remember in a different way.”

— Source: Duke Medicine News and Communications

High Blood Pressure May Make It Difficult for Elders to Think Clearly

A new study from North Carolina State University shows that increased blood pressure in older adults is directly related to decreased cognitive functioning, particularly among seniors who already have high blood pressure. This means that stressful situations may make it more difficult for some seniors to think clearly.

Jason Allaire, PhD, the study’s coauthor and an assistant professor of psychology at the university, explains that study subjects whose average systolic blood pressure was 130 or higher saw a significant decrease in cognitive function when their blood pressure spiked. However, he notes, study subjects whose average blood pressure was low or normal saw no change in their cognitive functioning, even when their blood pressure shot up.

Specifically, Allaire says, the study shows a link between blood pressure spikes in seniors with high blood pressure and a decrease in their inductive reasoning. “Inductive reasoning is important,” he says, “because it is essentially the ability to work flexibly with unfamiliar information and find solutions.”

Allaire says the findings may indicate that mental stress is partially responsible for the increase in blood pressure and the corresponding breakdown in cognitive functioning. However, he notes that normal fluctuations in blood pressure likely play a role as well.

The study, which was published in the Journal of Gerontology: Psychological Sciences, examined blood pressure and cognitive functioning test data collected from a cohort of adults aged 60 to 87 twice daily for 60 days.

— Source: North Carolina State University