Smoking brings on dementia

Over 55 years old and smoke? You're significantly more likely to develop dementia or Alzheimer's disease than people who never smoked or have quit, findings from a Dutch study suggest.

"Over seven years of follow up, those who currently smoked were 50 percent more likely to develop dementia than those who had never smoked, while past-smokers had a slightly increased risk of develop dementia," Dr Monique Breteler told Reuters Health.

Breteler and colleagues, at Erasmus Medical Centre, Rotterdam, followed 6 868 men and women, aged 55 years and older (average, 69.5 years) and initially without dementia, to assess associations between smoking and the development of dementia.

Overall, 22.6 percent of the study participants were current smokers at the start of the study and 41.6 percent were past smokers, the researchers report in the medical journal Neurology.

The researchers report that 10.3 percent of the participants developed dementia and over three-quarters of these were diagnosed with Alzheimer's disease.

Much higher risk
After adjusting for age and gender, the investigators found that current smokers had a 47 percent higher risk of dementia and a 56 percent higher risk of Alzheimer's disease than those who had never smoked. The corresponding increases in risk for former smokers were 15 percent and 17 percent.

Breteler and colleagues further investigated the association between smoking and the development of dementia among participants who either did or did not carry the e4 form of the apolipoprotein gene that is associated with an increased risk for Alzheimer's disease.

They found that the effect of smoking is more pronounced in people without the e4 variant, possibly because e4 carriers "may have an increased risk of Alzheimer's disease in such a way that other risk factors do not increase the risk further." – (Reuters Health)

Read more:
Stop Smoking Centre
Alzheimer’s Centre

September 2007