If you’re a woman, being highly physically fit in middle age may provide an advantage years later with respect to dementia — an 11-year advantage, according to research published this month in the journal Neurology. That’s how much longer, on average, women with high cardiovascular fitness in midlife lived dementia-free, compared with women moderately fit at midlife. The research tracked 191 women for 44 years, from their 50s into their 90s, determining their fitness level through bicycle exercise tests that measured cardiovascular fitness. Women who were the most fit at midlife were 88 percent less likely than the moderately fit to develop dementia later on. But highly fit women who did develop dementia did so at age 90, on average, rather than at 79. Although memory loss is often an early symptom, dementia includes a broader loss of thinking skills — the ability to think, problem-solve and reason — that interfere with daily functioning. This is just one small study, and it only found an association, but it points to what experts believe is an important effect of exercise on the brain: Dementia usually stems from the loss of brain cells, but numerous studies have found that exercise promotes the growth of new blood vessels in the brain and healthier brain cells.