London, Mar 15 (IANS): Women with high physical fitness in middle age were nearly 90 per cent less likely to develop dementia, compared to women who were moderately fit, according to a study.

When the highly fit women did develop dementia, they developed the disease an average of 11 years later than those women who were moderately fit, or at age 90 instead of age 79.

"These findings are exciting because it's possible that improving people's cardiovascular fitness in middle age could delay or even prevent them from developing dementia," said Helena Horder from the University of Gothenburg in Sweden.

For the study, published in the journal Neurology, 191 women with an average age of 50 took a bicycle exercise test until they were exhausted to measure their peak cardiovascular capacity.

The women were tested for dementia six times.

The results showed five per cent of the highly fit women developed dementia, compared to 25 per cent of moderately fit women and 32 per cent of the women with low fitness.

The highly fit women were 88 per cent less likely to develop dementia than the moderately fit women.

Among the women who had to stop the exercise test due to problems, 45 per cent developed dementia decades later.

"This indicates that negative cardiovascular processes may be happening in midlife that could increase the risk of dementia much later in life," Horder said.

"More research is needed to see if improved fitness could have a positive effect on the risk of dementia and also to look at when during a lifetime a high fitness level is most important." he said.