Ninety-somethings seem to be getting smarter.

Today's oldest people are surviving longer, and thankfully appear to have sharper minds than the people reaching their 90s 10 years ago.

During research, which spanned 12 years and involved more than 5 000 people, the team gave nonagenarians born in 1905 and 1915 a standard test called a "mini-mental state examination", and cognitive tests designed to pick up age-related changes.

Kaare Christensen, head of the Danish Aging Research Center at the University of Southern Denmark, and colleagues found Danish people born in 1915 were about a third more likely to live to their 90s than those born in 1905, and were smarter too.

It's a landmark study, says Marcel Olde Rikkert at Radboud University Nijmegen Medical Centre in the Netherlands.

It is scientifically rigorous, it invited all over 90-year-olds in Denmark to participate, and it also overturns our ingrained views of old age, he also says.

Not only did those born in 1915 do better at both sets of tests, more of them also scored top marks in the mini-mental state exam.

Olde Rikkert adds that cognitive function can actually be a lot better than people would assume until a very high age.

Tellingly, there was no difference in the physical test results between the two groups.

The authors say this "suggests changes in the intellectual environment rather than in the physical environment are the basis for the improvement". Thank you.