Denise Park selected 350 volunteers, ranging from 20-somethings to octogenarians. They sat 11 tests on visual, spatial, verbal, and other types of memory. She found that performance in all the tests decreased steadily with age-the decline in performance between the 70s and 80s age groups, for example, was the same as that between the 20s and 30s.
The findings, which Park will present at the American Psychological Association's annual meeting in San Francisco next week, run counter to the popular notion that mental abilities decline sharply after a particular age. "It's not as though you hit 60 or 70 and fall apart. We're falling apart as we speak," she says.
The results are surprising both because the decline starts so early and because it seems to happen at the same rate for many different memory tasks, says Fergus Craik, a psychologist at the University of Toronto.
Park suggests this lockstep decline may point to a global mechanism that has a uniform effect across the brain, such as a breakdown in neural signalling. But Craik warns the study could have missed differences between various kinds of memory by averaging results for each age group instead of following individuals across their lifespan.
Either way, the findings may not be as bleak as they sound. Park says young adults are unlikely to notice any change because they have more than enough reserve brainpower to handle most situations. And middle-aged people may be able to use their life experience to compensate for memory loss.
"People in their 50s and 60s are at their peak in their careers and in terms of what they're doing with their lives," says Michael Rugg, a neuroscientist at University College London. "But if you take them into the lab and run difficult cognitive tests, they won't do as well as someone in their 20s."
Author: Greg Miller
New Scientist issue: 25th August 2001
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