Smoking and Alzheimers

Heavy smoking in midlife may more than double odds of developing Alzheimer's disease.
USA Today (10/26, Marcus) reports that, according to a study published online Oct. 25 in the Archives of Internal Medicine, "heavy smoking in midlife more than doubles your odds of developing Alzheimer's disease." For the study, researchers from Kaiser Permanente "evaluated the records of 21,123 men and women in midlife and continued following them, on average, for 23 years." They found that, "compared with non-smokers, those who had smoked two packs of cigarettes a day increased their risk of developing Alzheimer's by more than 157% and had a 172% higher risk of developing vascular dementia -- the second most common form of dementia after Alzheimer's."
The Wall Street Journal (10/26, D3, Wang) reports that smokers who did not smoke so heavily still faced an increased risk for dementia. For example, even smokers who smoked just half a pack of cigarettes daily still had a 37% increased risk for Alzheimer's.
Bloomberg News (10/26, Ostrow) points out the public health implications of the study, noting that "about 46 million Americans ages 18 or older are cigarette smokers, according to the US Centers for Disease Control and Prevention." The study's lead author explained that "smoking causes higher levels of inflammation in the body and affects how blood clots." In addition, "smokers are...more likely to have strokes, high blood pressure, and cerebrovascular disease -- a malady of the blood vessels, particularly the arteries that supply the brain -- which are all risk factors for dementia, she said."
According to the CNN (10/25, Landau) "The Chart" blog, people "who smoked between one and two packs had a 44 percent heightened risk, compared to non-smokers." However, "this could be an underestimation, because some smokers who would have developed dementia died before diagnosis, said Kenneth Hepburn, associate dean for research at the Emory University School of Nursing, who was not involved in the study." What's more, "the reported risk of dementia among heavy smokers is also likely an underestimation because many of those people will die before they're old enough to develop dementia, he said."
"Former smokers and people who smoked less than half a pack a day did not appear to be at increased risk of Alzheimer's or vascular dementia," HealthDay (10/25, Reinberg) reported. Still, "the associations between smoking and dementia did not change, even after adjusting for race or gender, high blood pressure, high cholesterol, or heart attack, stroke or weight," the study authors added.