Obesity in midlife is linked to a greater risk of dementia later in life among women, new research suggests, but poor diet and inactivity are not.
Researchers found that women who were obese at the start of the study had a 21 per cent greater risk of dementia compared with women with a desirable BMI.
The study involved more than one million women born in the UK between 1935 and 1950.
They had an average age of 56 and did not have dementia at the start of the study.
Scientists followed the women for an average of 18 years and 15 years from the start of the study, 18,695 women were diagnosed with dementia.
Among the obese women, 2.1 per cent, were diagnosed with dementia.
This is compared with 1.6 per cent of women with a desirable BMI.
Study author Dr Sarah Floud, from the University of Oxford, said eating poorly and being inactive may be due to early symptoms of dementia.
Dr Floud said: "Other studies have shown that people become inactive and lose weight for up to a decade before they are diagnosed with dementia.
"On the other hand, obesity in midlife was linked with dementia 15 or more years later.
"Obesity is a well-established risk factor for cerebrovascular disease. Cerebrovascular disease contributes to dementia later in life."
Australian Associated Press