Twenty-three years later, about one-quarter of the group, or 5,367, had
dementia, including 1,136 with Alzheimer’s disease and 416 with vascular
dementia.
After adjusting for other factors, the researchers concluded that pack-a-day smokers were 37 percent more likely than
nonsmokers to develop
dementia, and the risks went up sharply with increased
smoking; 44 percent for one to two packs a day; and twice the risk for more than two packs.
Former smokers and those who
smoked less than half a pack a day were no more likely to develop
dementia than
nonsmokers. The study was published online on Monday in Archives of Internal Medicine.
To its lead author, Dr. Rachel A. Whitmer, an epidemiologist with the Kaiser Permanente Division of Research in Oakland, Calif., the study offered a silver lining: unlike age and family history, she said, “this is one risk factor for
dementia that can be changed.”