Tokyo, Dec 07: Fruit flies grow senile as they age, just as humans do, according to Japanese-led research. It is the first time in the world that senility has been confirmed in any creature other than mammals, Minoru Saitoe, chief scientist at the Tokyo Metropolitan Institute for Neuroscience, said on Friday.

"The memory of drosophilas (scientific name for flies) deteriorates as they get older," he said, with one specific amnesiac gene affecting the middle-term memory, which vanishes in seven to eight hours.

Fruit flies have a short life of about 40 days, and they get senile roughly at day 20, equivalent to 40 years in human terms, he said.

Saitoe found that older fruit flies were more inclined to forget to avoid a specially scented chamber where they had been subjected to mild electric shocks than younger ones.

Saitoe said he had also found one specific gene impaired middle-term memory, causing senile dementia. The finding "will enable us to target the amnesiac gene in mice for finding a major step towards improving the treatment of age-related memory impairment (in humans)", he said.

Short-lived flies are suitable for gene study as researchers are able to see the consequences of destroying a gene over a short period of time, while it would take two-to-three years to see the results in mice, he said.

"Besides, we do not need much space to keep flies," he added.