Geezers rejoice

Brains of elderly slow because they know so much

The brains of older people only appear to slow down because they have so much information to compute, much like a full-up hard drive, scientists believe.

Older people do not decline mentally with age, it just takes them longer to recall facts because they have more information in their brains, scientists believe.

Much like a computer struggles as the hard drive gets full up, so to do humans take longer to access information, it has been suggested.

Researchers say this slowing down it is not the same as cognitive decline.

“The human brain works slower in old age,” said Dr. Michael Ramscar, “but only because we have stored more information over time

“The brains of older people do not get weak. On the contrary, they simply know more.”

A team at Tübingen University in Germany programmed a computer to read a certain amount each day and learn new words and commands.

When the researchers let a computer “read” only so much, its performance on cognitive tests resembled that of a young adult.

But if the same computer was exposed to the experiences we might encounter over a lifetime – with reading simulated over decades – its performance now looked like that of an older adult.

Often it was slower, but not because its processing capacity had declined. Rather, increased “experience” had caused the computer’s database to grow, giving it more data to process – which takes time.

“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 2000 people, but can ‘only’ match the right person to the right birthday nine times out of ten?” said Dr Ramscar.

The study provides more than an explanation of why, in the light of all the extra information they have to process, we might expect older brains to seem slower and more forgetful than younger brains.

And researchers say some cognitive tests which are used to study mental capacity may inadvertently favour young people.

A cognitive test called ‘paired associated learning’ invites people to remember a pair of words that are unrelated like ‘necktie’ and ‘cracker.’

Studies have shown that young people are better at this test, but scientists think that older people struggle to remember nonsense pairs – like ‘necktie’ and ‘cracker’ – because they have learned that they never go together.

Prof. Harald Baayen, who heads the Alexander von Humboldt Quantitative Linguistics research group where the work was carried out said: “The fact that older adults find nonsense 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.”

Scientists say this could explain why older people struggle to remember unusual first names.

The study was published in the Journal of Topics in Cognitive Science