Passive smoking can cause dementia

People exposed to secondhand smoke may face as much as a 44 percent increased risk of developing dementia.

Smoking is already known to increase the risk for dementia and Alzheimer’s disease.

A study from Peninsula Medical School in Exeter, England published in the journal BMJ has shown that there is an association between cognitive function and exposure to passive smoking. The risk increases with the amount of exposure to secondhand smoke. For people at the highest levels of exposure, the risk is probably higher.

The study collected data on more than 4,800 nonsmokers who were over 50 years old and tested saliva samples from these people for levels of cotinine, a product of nicotine that can be found in saliva for about 25 hours after exposure to smoke. The researchers found that people with the highest cotinine levels had a 44 percent increased risk of cognitive impairment, compared with people with the lowest cotinine levels. And, while the risk of impairment was lower in people with lower cotinine levels, the risk was still significant.

Passive smoking is also associated with an increased risk of stroke and heart disease