How Your Aging Brain Is Like A Spam Filter

Remembering things may get more difficult with age. You may not process information as fast as you once did. But changes in your brain may also promote happiness and emotional stability, according to recent brain imaging research.

While there is the general perception that the brain begins a downhill slide beginning in middle age, that isn't true for all aspects of mental function. Previous research has found that with increasing age, there is "less negativity, an easing of emotional intensity, and a reduction in trait neuroticism, reflecting better emotional stability." Older adults have been found to have more positive emotions and fewer negative ones. In some ways, an older brain is a better brain.

But that research was based on observation and self-reporting, and did not measure or explain what was happening inside the brain. The new study sought to correct that. It was conducted by researchers at the University of Sydney and published in the Journal of Neuroscience (it's available here).

The team first used surveys and then measurement and imaging techniques to assess how people of different ages process fear and happiness responses.

Younger people were more able to recognize fear in others' faces, while older people could better recognize happiness. Separately, they found that the most neurotic (read that as a catchall for "troubled") subjects were teenagers, and the least were people aged 50 - 79.

The brain scans showed that when older people processed negative emotions, their brain was more active than when dealing with positive ones. It seems that older brains work hard to filter out unpleasant feelings. Like the spam filter on your email software, it works in the background to make sure you don't see (or in this case, feel) the bad stuff.

The team concluded that "emotional wellbeing improves over seven decades of the human lifespan, reflected in better emotional stability and an easing of perceived emotional intensity as a function of age." They posit that the brain becomes more selective in how it processes emotions; this selectivity could be driven by life experiences, changing motivations, or simply the learned ability of the brain to dampen unpleasantness.

The BBC headlined this "The Brain Gets 'Mellow' With Age," and the Sydney team themselves titled their report "The Mellow Years?: Neural Basis of Improving Emotional Stability over Age."

(Rumors that the research was funded by fellow Aussie Olivia Newton-John in an attempt to promote "Have You Never Been Mellow" weren't substantiated by LifeTwo).

Why our brains age this way is still a mystery. There is no obvious selective evolutionary benefit to behavior that occurs after the reproductive years. One possibility is that a mellower elder may benefit his or her entire family or clan.