Beautiful Science: The ‘Middle-aged Brain’

For years it was assumed that as we age and our bodies started to slow, our emotions would generally follow suit. We would become duller, less motivated, and more unhappy with life. That was the prevailing view for a long time, even among neuroscientists, possibly because the assumption seems to make perfect sense.

But it was a wrong.

When research on the aging brain began in earnest (this is a relatively new field of study), quite the opposite turned out to be true. As we age, our emotions not only remain largely intact, we also become considerably happier, all other things considered (notably our health and living situations).

Mara Mather is a cognitive psychologist and professor of gerontology and psychology at the USC Davis School of Gerontology. Mather and her colleagues have done significant research on the emotional aspects of the middle-age brain. Her research has shown that as we get older, in a remarkably linear fashion, our brain react less to negative things. Over and over, Mather and other researchers like Laura Carstensen at Stanford and John Gabrieli, a neuroscientist at MIT and the McGovern Institute for Brain Research, broadly got the same result. When older subjects are shown positive and negative images, their amygdala – the small almond-shaped structure in the brain that triggers heightened responses to threatening stimuli – respond less and less to negative stimuli. Since nature has evolved the amygdala to react most intensely to negative stimuli, this finding is extraordinary. It appears that our middle-aged brains – in some automatic semiconscious way – are accentuating the positive and downplaying the negative. As Carstensen sums up, “Older people clearly showed preference in memory and attention for positive over negative.”

What is going on?

It seems that it boils down to how we regulate our responses to the negative. Carstensen again: “Our research team has informally asked scores of older people how they regulate their emotions particularly during difficult periods in their lives. Regularly, they responded with the answer: ‘I just don’t think about it [the problems or worries].’ At first, this statement seemed to offer little insight into how older adults were regulating their feelings; however, the consistency of their responses made us turn to the possibility that processing positive and negative information may vary as a function of age.” In other words, the superior ability of older people to “tune out” negative information comes from aging itself.

This conclusion was not reached lightly, but was based on a whole raft of studies that looked at the puzzle from every possible angle. In one example, Carstensen wondered whether it was because people didn’t remember negative information or perhaps, they ignored it altogether. But that was not it. First, when older subjects were presented one image at a time, they looked at negative pictures longer than positive ones, the same as younger people.

Could it be that negative images were harder to process as we age? Again, this wasn’t it. As one researcher commented, negative information is much more potent and remains much easier for brains to recognize and process (which makes sense from an evolutionary angle). Hence, even in middle age, our brains still register the bad things around us. Or could it be that the amygdala begins to wear out as we age, so that no matter how potent the negative message, it doesn’t register as strongly? In further studies, Mather found that as we age, our brains respond just as robustly to threats, which indicates that our amygdala is still holding out as we get older.

Mara Mather, Professor of Gerontology and Psychology, University of Southern California.

So, we’re back to square one. What could be the reason for what Carstensen and her team call “the positivity effect?” – the increase in focus on the positive as we age? In the end, the researchers were left with only one real answer: we choose to be happier by focusing more on the positive than the negative.  But why?

Plausible reasons are not hard to find. Carstensen argues that as we age, we become much more aware that we have less time on earth, and therefore, it becomes more important to “let go” of negative emotions and emphasize the more positive aspects of life. As she puts it, “time perspective is the dominating force that structure human motivations and goals. When time is perceived to be expansive, as it is for healthy, young adults, goal striving is valued and investments are made in expanding horizons. In contrast, when time is perceived as limited, emotional experience assumes primacy.”

You could say that older folks are giving themselves a “positive spin” on things to make the most of their limited time. And that is a good thing, not only for the older folks themselves but this “positivity effect” may have evolved because it works well for the group because happier seniors are likely to be in a better position to look after the younger charges in their care than grouchy, depressed ones.

The idea that older people choose to feel more positive about themselves is also supported by other studies using brain scanning. Joseph Mikels at DePaul University, for example, has found that older adults who emphasize the positive side of life the most also use their orbitofrontal cortex, a well-developed part of the human brain that regulates attention, decision-making and emotions. Says Mikels, “This is not a result of older people wearing rose-colored glasses, but a function of their brains, which they have activated, and regulated to focus on the positive and away from the negative … We do it on some level on purpose. The ability to regulate emotion increases with age. This is one of the really good things about the middle-aged brain.”

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