Middle-aged people who smoke heavily may be at twice the risk for developing Alzheimer’s and dementia later in life.
A new study conducted by Finnish scientists concluded these findings after analyzing more than 21,000 people over a period of two decades.
Led by Minna Rusanen, M.D., of the University of Eastern Finland and Kuopio University Hospital, a team of researchers identified 21,123 members of one health care system for the study and had them participate in a survey between 1978 and 1985. At that time, participants ranged in age from 50 to 60 years old.
Two decades later — from 1994 through 2008 — researchers tracked the rate of dementia, Alzheimer’s disease and vascular dementia, when participants were an average of 72 years old.
“To our knowledge, this is the first study evaluating the amount of midlife smoking on long-term risk of dementia and dementia subtypes in a large multiethnic cohort,” researchers write.
“Our study suggests that heavy smoking in middle age increases the risk of both Alzheimer’s disease and vascular dementia for men and women across different race groups.”
They added that these findings lend to greater concern regarding the potential growing impact that smoking may continue to have on public health as the population worldwide ages and dementia prevalence increases.
Background information provided by researchers in an article reveals current statistics suggesting that smoking is responsible for several million deaths per year. The majority of these deaths come from heart disease and cancer.
Although smoking increases risks of most diseases and of death, some studies have shown a reduced risk of Parkinson’s disease and other neurodegenerative conditions among smokers.
The link between smoking and risk of Alzheimer’s disease, the most common subtype of dementia, has been somewhat controversial, with some studies suggesting that smoking reduces the risk of cognitive impairment, the authors note in the article.
In the Finnish study, a total of 5,367 participants were diagnosed with dementia during an average span of 23 years when followup was completed. Of these, there were 1,136 diagnosed with Alzheimer’s disease and 416 with vascular dementia.
Those who smoked the heaviest — more than two packs per day — during their middle-aged years had a higher risk of dementia, Alzheimer’s disease and vascular dementia, when compared with nonsmokers. For former smokers, or those who smoked less than half a pack per day, there did not appear to be at increased risk.
There were no links found in the results to a particular gender or race.
Since smoking is an identified risk factor for stroke, researchers suggested that the habit may contribute to the risk of vascular dementia through similar mechanisms. In addition, smoking contributes to oxidative stress and inflammation, which believed to be important in the development of Alzheimer’s disease.
Findings from the study will be published in February 28 print issue of Archives of Internal Medicine.