Tue, Jan 20, 2009 - Page 16 News List

[SCIENCE] Nostalgic tendencies

The elderly filter out negative memories,a scientific study has revealed



In the 1973 film The Way We Were, Barbra Streisand sings a haunting ballad about memories and aging. “What’s too painful to remember, we simply choose to forget,” the song goes.

Now, research suggests that the song was essentially right, and illustrates just how the brain manages to dismiss negative memories but retain the positive ones as we get older.

A team of researchers from Duke University and University of Alberta took two groups of volunteers — one in their mid-20s, one in their 70s — and showed them photos that were either neutral or very negative, depicting such things as mutilated bodies or sick children. Later, the participants were unexpectedly asked to recall the images. The older group had a harder time recalling the negative images than the younger group, and brain scans revealed the differences in brain activity between the two groups.

The study — which points to possible ways to improve memory in aging adults — appears in the January issue of Psychological Science. Peggy St Jacques, the Duke University graduate student in psychology and cognitive neuroscience who is the lead author, said there are primal reasons why seniors tend to take a dim view of unpleasant memories.

“As we age, we have a more limited perspective of the time we have left,” she said, “so we may focus more on things that increase our emotional well-being.”

In practical terms, that might mean that an older person’s memory of the family reunion will focus on the delights of the grandchildren playing on the lawn, not the shouting match at lunch over their divorcing parents’ custody battle. Or on the glow of the sunset over the dunes, not the litter scattered across the sand.

“Not everything that happens with aging is negative,” says Gene Cohen, director of the center on aging, health and humanities at George Washington University.

There are related advantages, he notes: People develop “longer fuses,” and are better able to control and regulate anger and other negative emotions. “The highs may be just as high, but the lows are not as low,” he said. And people with certain conditions such as social phobias often find their illnesses diminishing with age, Cohen said.

St Jacques’s study is not the first to show how the aging brain filters out the negative.

Other scientists, most notably Stanford University psychologist Laura Carstensen, have also demonstrated that seniors tend to remember more positive than negative events. And still other research has revealed that in brain scans the amygdala, the brain’s emotion detector, lights up equally intensely in young and old while viewing positive events, yet does not light up as brightly or as long in older people when they view negative images.

But St Jacques’s study, while small in the number of participants — there were 15 people in each group — is the first to trace the pathway of an emotional memory in the brain as it is formed, and to look at the age-related differences.

Brain scans taken while the participants viewed the pictures revealed that while both groups had similar activity in the brain’s emotional center, they differed when it came to how the centers interacted with the rest of the brain. Younger people were connecting more with another region of their brain typically associated with learning and memory, known as the hippocampus, while older adults relied more on a portion involved in controlling emotions, called the frontal cortex.

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