It used to be, "If you got 'em, smoke 'em." But these days, medical professionals in Dallas, Houston and elsewhere in Texas, seriously frown on tobacco use. In fact, more studies and research are pointing out that even secondhand smoke can cause many serious ailments including cancer. Now, according to a recent study, exposure to secondhand tobacco smoke increases the risk of developing dementia in individuals.

In a recent Cardiovascular Health Study -- supported by a grant from the Flight Attendant Medical Research Institute, University of California, San Francisco -- researchers evaluated 3,602 people age 65 and older, with 985 people who had no cardiovascular disease, no dementia, and were never smokers.

Four hundred and ninety-five people reported their lifetime secondhand smoke exposure, with an average of approximately 28 years. Researchers then evaluated which individuals developed dementia over a six-year period.

Based on preliminary results, the researchers found that elderly people with high lifetime exposure to environmental smoke were approximately 30 percent more likely to develop dementia than those with no lifetime exposure. High exposure, in the case of this study, was defined as exposure to secondhand smoke for more than 30 years.

"We are still conducting analyses to control for other factors that may be influencing these results, but this finding potentially implicates lifetime exposure as a risk factor for dementia in older adults," said study author Thaddeus Haight of UC Berkeley.

The study also found that exposure to secondhand smoke resulted in a greater occurrence of dementia for people who didn't have a diagnosis of cardiovascular disease, but who had detectable abnormalities of their carotid arteries, compared to those without these underlying abnormalities.

These abnormalities included narrower carotid arteries and thicker carotid arterial walls. Individuals with these underlying conditions and high lifetime exposure were nearly two-and-a-half times as likely to develop dementia as those with no exposure and no indications of carotid artery disease.

"This is one of the first studies to look at the risk of dementia in people who never smoked, but were exposed to environmental smoke," Haight said. "These results show that exposure is associated with increased risk of dementia, even in people without known risk factors for dementia related to diagnosed cardiovascular disease."

The researchers used statistical methods to assess the associated risk of exposure to independent of its known effects on clinically diagnosed cardiovascular disease. "The fact that there were more people in this study population who were not diagnosed, but had underlying cardiovascular disease compared to people who were diagnosed points to the health risks associated with lifetime exposure in a potentially wider segment of the elderly population," said Haight.

Haight said the study findings provide additional evidence of the hazards of secondhand smoke and provide additional support for policies that seek to reduce the public's exposure to tobacco smoke.

Here are other facts, compiled by the American Lung Association, about secondhand smoke:

- Secondhand smoke has been classified by the Environmental Protection Agency (EPA) as a known cause of cancer in humans (Group A carcinogen).

- Exposure causes disease and premature death in children and adults who do not smoke. Secondhand smoke contains hundreds of chemicals known to be toxic or carcinogenic, including formaldehyde, benzene, vinyl chloride, arsenic ammonia and hydrogen cyanide.

- SHS (Second Hand Smoke) causes approximately 3,400 lung cancer deaths and 22,700-69,600 heart disease deaths in adult nonsmokers in the United States each year.

- A study found that nonsmokers exposed to environmental smoke were 25 percent more likely to have coronary heart diseases, compared to nonsmokers not exposed to smoke.

- Nonsmokers exposed to environmental smoke at work are at increased risk for adverse health effects. Levels of secondhand smoke in restaurants and bars were found to be 2 to 5 times higher than in residences with smokers and 2 to 6 times higher than in office workplaces.

- Workplace productivity was increased and absenteeism was decreased among former smokers, compared to current smokers

- Smoke is especially harmful to young children. Secondhand smoke is responsible for between 150,000 and 300,000 lower respiratory tract infections in infants and children under 18 months of age, resulting in between 7,500 and 15,000 hospitalizations each year, and causes 1,900 to 2,700 sudden infant death syndrome (SIDS) deaths in the United States annually.

- Environmental smoke exposure may cause buildup of fluid in the middle ear, resulting in 700,000 to 1.6 million physician office visits per year. Smoke can also aggravate symptoms in 400,000 to 1,000,000 children with asthma.

- New research indicates that private research conducted by cigarette company Philip Morris in the 1980s showed that environmental smoke was highly toxic, yet the company suppressed the finding during the next two decades.

- The current Surgeon General's Report concluded that scientific evidence indicates that there is no risk-free level of exposure to smoke. Short exposures to environmental smoke can cause blood platelets to become stickier, damage the lining of blood vessels, decrease coronary flow velocity reserves, and reduce heart rate variability, potentially increasing the risk of heart attack.