A link between Alzheimer's and smoking has been shown before, but this new study pinpoints the specific risk for middle-age smokers for developing both Alzheimer's and vascular dementia, the researchers say.
Smoking, an established risk factor for stroke, may contribute to the likelihood of vascular dementia by causing small clots in the brain. Smoking also contributes to oxidative stress and inflammation, which may be linked to the risk of developing Alzheimer's disease, the researchers say.
"The brain is not immune to long-term damage from smoking," Whitmer said.
Two smaller studies of predominantly white participants also suggested that mid-life smoking raised the risk of developing Alzheimer's, researchers noted.
Commenting on the new study, William Thies, chief medical and scientific officer at the Alzheimer's Association, said "this is a sound confirmation of something that's been known for a while."
Another expert, Dr. Samuel E. Gandy, the Mount Sinai Professor of Alzheimer's Disease Research at Mount Sinai School of Medicine in New York City, said the findings are promising.
"Environmental factors in Alzheimer's disease have been long sought, and, until now, only head injury has emerged," Gandy said. "Unlike head injury, a tobacco smoking association is especially important because that is a risk that can be modified."
For more information on Alzheimer's disease, visit the Alzheimer's Association.
SOURCES: Rachel A. Whitmer, Ph.D., research scientist, Kaiser Permanente Division of Research, Oakland, Calif; William Thies, Ph.D., Chief Medical and Scientific Officer, Alzheimer's Association; Samuel E. Gandy, M.D., Ph.D., Mount Sinai Professor of Alzheimer's Disease Research, Mount Sinai School of Medicine, New York City; Oct. 25, 2010, Arch
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