Exposure to secondhand tobacco smoke increases the risk of developing dementia, a new study has found.
The researchers evaluated 3,602 people aged 65 and older. Of these, 985 had no cardiovascular disease, no dementia and were never smokers. Some 495 people reported exposure to smoke, for an average of 28 years.
They were monitored over six years for the development of dementia.
It was found that those with a high lifetime exposure to smoke, defined as more than 30 years, were 30 per cent more likely to develop dementia than those with no lifetime exposure.
Thaddeus Haight, author of the study, said: "This finding potentially implicates lifetime exposure to secondhand tobacco smoke as a risk factor for dementia in older adults.
"This is one of the first studies to look at the risk of dementia in people who never smoked, but were exposed to secondhand smoke.
"These results show that secondhand smoke is associated with increased risk of dementia, even in people without known risk factors for dementia related to diagnosed cardiovascular disease."