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Secondhand Smoke Linked to Dementia
< May 02, 2007 > -- Breathing in secondhand smoke could raise your risk for dementia, a new study finds.
It is the first study to link secondhand smoke to this form of mental deterioration, says lead researcher Dr. Thaddeus Haight, a research statistician at the University of California, Berkeley. The study was presented this week at the annual meeting of the American Academy of Neurology.
"There have been studies that have shown that exposure to secondhand smoke is related to subclinical cardiovascular disease and clinical cardiovascular disease," Dr. Haight notes. "There also have been studies showing that atherosclerosis, hardening of the arteries, is related to an increased risk of dementia."
Dementia occurs when thinking is impaired, but perception and consciousness are not. It can be caused by a variety of disorders including severe infections, toxins, and structural brain diseases such as Alzheimer's.
The current study completes the loop by showing that inhaling someone else's smoke increases the incidence of dementia, according to Dr. Haight.
"This study attempts to look at the relationship between cardiovascular disease and dementia and also looks at the independent, direct effects of tobacco on the nervous system," Dr. Haight says.
"There is an alternative pathway other than cardiovascular disease with potential neurotoxic effects. Secondhand smoke could affect the neurodegenerative process behind dementia and may lower the threshold for dementia-like symptoms."
Analysis of the data shows that the combination of long-term exposure to secondhand smoke and the presence of cardiovascular disease nearly doubles the risk of dementia. Long-term exposure to secondhand smoke alone increased the risk of dementia by about a third.
In their study, the Berkeley team evaluated data on more than 3,600 participants enrolled in a long-running study of cardiovascular health. They compared 985 never-smokers with no cardiovascular disease and no dementia to 495 people who reported an average of 28 years of lifetime exposure to another person's smoking.
A six-year evaluation revealed that elderly people exposed to secondhand smoke for 30 years or more were about 30 percent more likely to develop dementia than those without such exposure, the researchers report.
"We're now looking at how smoke affected dementia directly and are also attempting to separate out the effects of secondhand smoke that occur through clinical vascular disease," Dr. Haight says.
The study also found a greater incidence of dementia in people who were not diagnosed with cardiovascular disease but who had detectable abnormalities of their carotid arteries, the main arteries to the brain, on ultrasound images.
People exposed to secondhand smoke who had abnormalities such as narrowed carotid arteries were 2.5 times more likely to develop dementia as those with no carotid abnormalities and no secondhand smoke exposure.
The study results provide support for efforts to reduce exposure to secondhand smoke, such as bans on smoking in restaurants and bars, Dr. Haight says.
"It's reasonable to suppose that anything that is bad for your heart is bad for your brain, so it is no great surprise that secondhand smoke could be responsible for development of carotid artery disease and dementias of all kinds," says Dr. Bill Thies, vice president for medical and scientific affairs at the Alzheimer's Association.
The exact degree of danger is somewhat unclear, because the data in the report are not complete, but the danger does exist, Dr. Thies says.
"This study is an important addition to the overwhelming evidence of serious health harms from secondhand smoke," says Matthew L. Myers, president of the Campaign for Tobacco-Free Kids. "It underscores the need for all states to pass comprehensive smoke-free laws covering all workplaces and public places."
Always consult your physician for more information.
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Seniors who consume high levels of calcium and vitamin D are much more likely to have larger brain lesions that can lead to cognitive impairment, depression or stroke, new research reveals.
The study authors point out that brain lesions of various sizes are not uncommon, even among healthy elders. However, the observation that the overall amount of brain matter affected by lesions goes up with vitamin intake is fueling concerns about a possible connection.
"This is one of the first studies to examine the relationship between diet and brain lesions," says study author Dr. Martha E. Payne, an assistant professor in the department of psychiatry and behavioral sciences with the Neuropsychiatric Imaging Research Laboratory at Duke University, in Durham, N.C.
"Since our study only looked at diet and brain lesions at one point in time, we cannot conclude that calcium or vitamin D caused the brain lesions that we found," she cautions. But she adds that "our finding of a relationship between brain lesions and consumption of both calcium and vitamin D raises the question about a possible downside to high intakes of these nutrients."
However, one nutritionist says it is still far too early to warn people away from calcium and vitamin D, which is vital to bone health. "In general, the problem is that people don't have enough intake of vitamin D and calcium, not too much," says Dr. Susan Harris, a nutritional epidemiologist and scientist at the US Department of Agriculture Nutrition Center at Tufts University, in Boston.
The authors note that calcium is also known to be important to proper nerve and muscle cell function.
According to the National Osteoporosis Foundation, vitamin D3 and calcium deficiency is a global problem. The organization's most recent scientific statement recommends that adults over the age of 50 consume 1,200 milligrams of calcium daily.
A daily total of 800 to 1,000 I.U. of vitamin D3 is also suggested, although the foundation cautions that supplementation at that level should only be taken with a physician's supervision.
In addition to ingesting it in supplement form, calcium can be found naturally in milk, cheese and broccoli, and is often added to fortify foods such as orange juice, cereals, and breakfast bars.
Vitamin D, key to good calcium absorption, is produced by the skin following exposure to the sun, although production decreases with age. Vitamin D is also found in foods such as saltwater fish (tuna for example), liver, and dairy products.
Always consult your physician for more information.
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