WHEN your dentist pulls an aching tooth they could be yanking out some of your memory at the same time, according to a new Swedish study to be presented in Stockholm tomorrow.

"Teeth appear to be of the utmost importance to our memories," Jan Bergdahl, an associate psychology professor at the Umeaa University in northern Sweden, a dentist and one of the authors of the study, said today.

For the study, which is part of a broader memory study called Betulastudien, researchers followed 1962 people aged 35 to 90 starting in 1988, comparing the memories of those who still had teeth and those who had pulled all their teeth and were using dentures.

"When people have no teeth their memories are clearly worse than when they have teeth," Mr Bergdahl said.

Recent Japanese studies on rats and monkeys have shown the link between teeth and memory but according to Mr Bergdahl this is the first large-scale study on humans that clearly connects the same dots.

While the Swedish research has yet to unveil what impact pulling a single tooth has on the human memory, Mr Bergdahl said that "going forward, we plan to look into how many teeth a person has to lose before it affects their memory. We will also investigate how tooth decay affects memory loss, and what affect tooth implants have".

He insisted however that he didn't expect future studies to reveal that implants improve memory.

"I don't think that is very probable. Animal tests have shown that pulling teeth severs nerves to the brain," Mr Bergdahl said, pointing out that the new Swedish study could dramatically change dental care for the elderly in the future.

"We might want to think twice before pulling out teeth that are a problem," he said.

Agence France-Presse, From correspondents in Stockholm, Sweden October 29, 2004