(NaturalNews) Exposure to secondhand smoke significantly increases a person's risk of developing severe dementia, according to a study conducted by researchers from China's Anhui Medical University and researchers from U.S. and U.K. universities, and published in the journal Occupational and Environmental Medicine.
Secondhand smoke is also known as environmental tobacco smoke (ETS) or passive smoking. Numerous studies have conclusively linked secondhand smoke exposure to dramatic increase in the risk of respiratory and cardiovascular diseases, such as lung cancer or coronary heart disease.
Studies have also shown that exposure to secondhand smoke is associated with an increased risk of cognitive impairment, and a recent study by Anhui Medical University researchers found a connection between secondhand smoke and the risk of Alzheimer's disease. But the new study is one of the first to look directly at the connection between secondhand smoke and the symptoms of severe dementia.
From 2001 to 2003, the researchers interviewed 5,921 people over the age of 60 in the Chinese communities of Anhui, Guangdong, Heilongjiang, Shanghai and Shanxi. Some communities were urban, while others were rural. Based on the interviews, researchers assessed participants' dementia symptoms. In follow-up interviews conducted in 2007 and 2008, the researchers reevaluated participants' dementia symptoms, along with their smoking habits and levels of secondhand smoke exposure.
China has the greatest number of dementia patients in the world, and the number continues to increase.
"China, along with many other countries, now has a significantly aging population, so dementia has a significant impact not only on the patients but on their families and careers," researcher Ruoling Chen said. "It's a huge burden on society."
Dangers of tobacco exposure
Approximately 10 percent of participants exhibited severe dementia symptoms at the end of the study. While having dementia did not increase the chance that a person would be exposed to more secondhand smoke, greater secondhand smoke exposure did increase the risk of dementia. This increased risk was seen in current smokers, former smokers and people who had never smoked at all.
"Passive smoking should be considered an important risk factor for severe dementia syndromes, as this study in China shows," Chen said. "Avoiding exposure to ETS may reduce the risk of severe dementia syndromes.
"The increased risk of severe dementia syndromes in those exposed to passive smoking is similar to increased risk of coronary heart disease," he said, "suggesting that urgent preventive measures should be taken, not just in China but many other countries.'
According to the World Health Organization, almost 80 percent of all smokers live in low- and middle income countries. China is home to 350 million smokers, making it the world's largest consumer of tobacco. Although smoke-free public areas have been promoted by the government since 2006, very few such areas have actually been implemented.
"At present, we know that about 90 percent of the world's population live in countries without smoke-free public areas," Chen said. "More campaigns against tobacco exposure in the general population will help decrease the risk of severe dementia syndromes and reduce the dementia epidemic worldwide."