Older people sometimes take longer to recall memories because their brains are overfilled with information, it has been claimed.
While forgetfulness can be a signal of the onset of conditions such as dementia, researchers at the Tubingen University in Germany say it is often simply because they have so many memories stored that it takes longer for their brains to pluck them out.
According to the Daily Telegraph, they likened this to a computer's hard drive slowing down when the data it holds gets close to capacity.
Dr Michael Ramscar, who led the study, said: "The human brain works slower in old age, 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."
The team tested the theory by using a computer that learned new words and commands each day.
When programmed to only read words, its ability was found to be on a par with a young adult. However, when it was also given "experiences" its ability slowed to that of an elderly person.
Professor Harald Baayan, head of the Alexander von Humboldt Quantitative Linguistics research group, believes past tests to compare the mental capacity of differing age groups have been flawed because they favour a younger person.
In particular, he is critical of 'paired associated learning', which asks people to remember unrelated words.
"The fact that older adults find nonsense pairs harder to learn than young adults simply demonstrates older adults’ much better understanding of language," he said.
A recent study from the John Hopkins University in the US found that taking a daily dose of caffeine can give people a short-term memory boost.
Researchers split 160 volunteers into two groups, with half being given the stimulant in tablet form and the remainder being given a placebo before their ability to recollect items was tested 24 hours later.
While those given caffeine had greater mental capacity initially, the study did not suggest that taking it long-term would garner any improvements.
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