October 26, 2010 - The study is the first to examine the long-term consequences of heavy smoking on Alzheimer's and vascular dementia, says the study's principal investigator, Rachel Whitmer, a research scientist with Kaiser Permanente in Oakland.
PAPER: Heavy Smoking in Midlife and Long-term Risk of Alzheimer Disease and Vascular Dementia, Minna Rusanen, MD; Miia Kivipelto, MD, PhD; Charles P. Quesenberry Jr, PhD; Jufen Zhou, MS; Rachel A. Whitmer, PhD, Arch Intern Med. Published online October 25, 2010, ABSTRACT..
Dementia and Second-hand Smoke: February 13, 2009 - A research study has for the first time shown a link between second-hand (environmental tobacco smoke, ETS, passive smoking, sidestream smoke, involuntary) exposure and development of dementia and other neurological problems in elderly non-smokers. (Second-hand smoke linked to dementia.)Researchers (in Finland, Sweden and at Kaiser Permanente in Oakland) followed an ethnically diverse population of 21,123 men and women from midlife onward for an average of 23 years. Compared with non-smokers, those who had smoked more than two packs of cigarettes a day had more than a 157 percent increased in risk of Alzheimer's disease and 172 percent increased risk of vascular dementia during the mean follow-up period of 23 years. Vascular dementia, the second most common form of dementia after Alzheimer's disease, is a group of dementia syndromes caused by conditions affecting the blood supply to the brain.
"This study shows that the brain is not immune to the long-term consequences of heavy smoking," said Dr. Whitmer. "We know smoking compromises the vascular system by affecting blood pressure and elevates blood clotting factors, and we know vascular health plays a role in risk of Alzheimer's disease."
Former smokers - those who had reported having quit by the start of the study - didn't have an increased risk of dementia. That finding dovetails with other work to suggest "that if you quit smoking after seven to 10 years, especially at a youn age, there is a lot of evidence you could be OK," Dr. Whitmer said.
Dr. Alois Alzheimer
The researchers say they think smoking's role in the development of Alzheimer's and vascular dementia may include a possible negative effects on brain blood vessels and brain cells.
Previous studies had raised questions about whether smoking provided a protective effect. Earlier studies suggesting protective efects of smoking were biased, due to the likelihood that a higher proportion of heavy smokers died before developing Alzheimer's disease.
"The other novel aspect of it is that they've got a large enough sample to look at different ethnic groups, and it shows smoking's effect on dementia does not differ based on race," says Brenda Plassman, director of the program in epidemiology, at Duke University's Dementia Department of Psychiatry.
Other authors of the paper include: Minna Rusanen, MD, the University of Eastern Finland and Kuopio University Hospital, Miia Kivipelto, MD, PhD, of the University of Eastern Finland and Karolinska Aging Research Center, and Charles P. Quesenberry, Jr, PhD, Jufen Zhou, MS. of the Kaiser Permanente Division of Research in Oakland, Calif.
David Sutton, a spokesman, for Richmond, Virginia-based Altria Group Inc., the largest U.S. tobacco company, said in an e-mail on Oct. 22 that Altria “agrees with the overwhelming medical and scientific consensus that cigarette smoking is addictive and causes serious diseases in smokers.”
Reference: Heavy Smoking Doubles Alzheimer's Disease, Dementia Risk, SOURCE Kaiser Permanente, 10/25/2010; Smoking in your 50s, 60s increases risk of dementia by Shirley S. Wang, The Wall Street Journal, 10/26/2010 - hard copy; Dementia Risk Rises in Smokers, Showing Another Reason to Quit, Study Says by Nicole Ostrow (email@example.com), Bloomberg.com, 10/25/2010.