Stop Smoking to Stop Dementia, Alzheimer's - Alzheimer's Risk Factors

Current smokers are 50 percent more likely to develop Alzheimer's disease or dementia than people who don't smoke or who gave up smoking, a Dutch report says.

Researchers announced these results after analyzing seven years of data from almost 7,000 people over age 55.

Over the course of the study, 706 people developed dementia. People who were smokers during the study were 50 percent more likely to develop dementia than people who had never smoked or were former smokers, according to the researchers, who published their findings in the Sept. 4 issue of Neurology.

"Smoking increases the risk of cerebrovascular disease, which is also tied to dementia," study author Dr. Monique Breteler, of Erasmus Medical Center in Rotterdam, the Netherlands, said in a prepared statement. "Another mechanism could be through oxidative stress, which can damage cells in the blood vessels and lead to hardening of the arteries. Smokers experience greater oxidative stress than nonsmokers, and increased oxidative stress is also seen in Alzheimer's disease."

Oxidative stress occurs when there are too many waste products from chemical reactions in the body. Dietary antioxidants can fight those waste products, known as free radicals, but Breteler said that smokers are also known to have fewer antioxidants in their diets than nonsmokers.

The researchers also studied the way that smoking affects the risk of Alzheimer's disease for people who carry the related gene. They found that smoking did not increase the risk for those with the gene for Alzheimer's disease, but it did increase the risk for people without the gene. Current smokers without the gene were 70 percent more likely to develop Alzheimer's disease than nonsmokers or former smokers without the gene.

Source:

American Academy of Neurology, news release, Sept. 3, 2007
Published:
Week of September 9 - September 15, 2007
By:
Madeline Vann, Healthday News
Permalink:
http://www.AlzWeek.com/node/79

___
http://www.ncbi.nlm.nih.gov/pubmed/17785668

Reitz C, den Heijer T, van Duijn C, Hofman A, Breteler MM. Relation between smoking and risk of dementia and Alzheimer disease: the Rotterdam Study. Neurology. 2007 Sep 4;69(10):998-1005.

BACKGROUND AND OBJECTIVE: Previous studies relating smoking with the risk of dementia have been inconsistent and limited in their validity by short follow-up times, large intervals between baseline and follow-up assessments, and unspecific determination of dementia diagnosis. We re-assessed after longer follow-up time in the large population-based cohort of the Rotterdam Study whether smoking habits and pack-years of smoking are associated with the risk of dementia, Alzheimer disease (AD), and vascular dementia (VaD).

METHODS: Prospective population-based cohort study in 6,868 participants, 55 years or older and free of dementia at baseline. First, Cox proportional hazard models were used to relate smoking status at baseline with the risks of incident dementia, VaD, and AD, using never smokers as the reference category in all analyses. Then Cox proportional hazard models were used to relate pack-years of smoking with the risks of incident dementia, VaD, and AD. To explore the impact of the APOEepsilon4 allele, sex, and age on the association between smoking status and dementia, we repeated all analyses stratifying, in separate models, by APOEepsilon4 genotype, sex, and median of age.

RESULTS: After a mean follow-up time of 7.1 years, current smoking at baseline was associated with an increased risk of dementia (HR 1.47, 95% CI 1.18 to 1.86) and AD (HR 1.56, 95% CI 1.21 to 2.02). This increase in disease risk was restricted to persons without the APOEepsilon4 allele. There was no association between current smoking and risk of VaD, and there was no association between past smoking and risk of dementia, AD, or VaD.

CONCLUSION: Current smoking increases the risk of dementia. This effect is more pronounced in persons without the APOEepsilon4 allele than APOEepsilon4 carriers.