By John Schappi
Results of an interesting study from Tübingen University in Germany make me feel better about my own forgetfulness.
The conclusions from that study suggest my brain isn't necessarily in some process of increasing cognitive impairment; I just know a lot more than I used to, and it takes longer for my gray matter to process all the information it now stores.
I'm liking those findings, but I can't help thinking about amyloid plaques, neurofibrillary tangles, etc.
Computer databases that resemble older brains
For the study, researchers trained computers to "read" a certain amount of new material every day. When a computer was exposed to a limited amount of information, it "performed" like a young adult on cognitive tests: pretty fast. When an identical computer was exposed to much more information—simulating the aggregate life experience of a much older adult—its performance on the same cognitive test resembled, not surprisingly, an older adult's: often more slowly.
The German scientists suggest that the brains of older adults—like the computers that approximated their greatly increased experience—work more slowly, not because their ability to process data had declined, but because they have to sort through and manage so much more material.
As head researcher Dr. Michael Ramscar summed up: "The human brain works slower in old age, but only because we have stored more information over time."
Please pass that thingamajig
Scientists can use computers to estimate the number of words that a person might learn in a lifetime. That new knowledge, the Tübingen team suggests, helps them differentiate between actual memory performance and the memory challenges posed by increasing amounts of stored information.
Ramscar poses this scenario:
Imagine someone who knows two people's birthdays and can recall them almost perfectly. Would you really want to say that person has a better memory than a person who knows the birthdays of 2,000 people, but can 'only' match the right person to the right birthday nine times out of ten? Researchers found that standard vocabulary tests—regularly used in studies about aging—are flawed, because they don't properly account for the amount of information stored in senior brains.
Said Tübingen researcher Peter Hendrix: "Forget about forgetting. If I wanted to get the computer to look like an older adult, I had to keep all the words it learned in memory and let them compete for attention."
More new names to remember?
Ramscar identifies what he considers another flaw in current assessments of what it means when seniors have trouble remembering names. A cultural shift has brought much greater name diversity into our vocabularies over the past two generations. That means it takes longer for older people to "locate" a particular name in their huge databases, just as it takes computers longer to find it when greatly increased data is involved.
There was another test: word pairing.
Subjects old and young were asked to connect—then remember—two words together, like "up" with "down" and "necktie" with "cracker"—the first a meaningful kind of word pair, and the second a nonsense pair. Young subjects did better remembering the nonsense pairs—not surprising.
Another conclusion was more interesting. Using computers to assess how often words appeared together in real language, researchers found that older adults correctly remembered pairs more as a function of their actual connections in the real world than younger adults.
How did the Tübingen team explain that difference?
Professor Harald Baayen, chief at the Alexander von Humboldt Quantitative Linguistics research group that conducted the study, said:
"If you think linguistic skill involves something like being able to choose one word given another, younger adults seem to do better in this task. But, of course, proper understanding of language involves more than this. You have also to not put plausible but wrong pairs of words together. The fact that older adults find nonsense pairs—but not connected pairs—harder to learn than young adults simply demonstrates older adults' much better understanding of language. They have to make more of an effort to learn unrelated word pairs because, unlike the youngsters, they know a lot about which words don't belong together."
A call for new tests to assess senior cognition
The researchers recommend new and different tests for assessing cognitive abilities in older people—tests that account for both the nature and the amount of information we process.
Said Dr. Ramscar, "The brains of older people do not get weak. On the contrary, they simply know more."
Now, where did I put my iPhone?