Alzheimer's, Dementia & Mental Health
Seniors Who Were Heavy Smokers in Midlife
Doubled Their Risk of Alzheimer’s, Dementia
Senior citizens
who smoked more than two packs per day in middle age had an elevated
risk of all dementias in study
Oct.
26, 2010 – Senior citizens who were heavy smokers in middle age appear
to have more than twice as much risk for Alzheimer’s disease and other
forms of dementia, according to a report posted online yesterday that
will be published in the February 28 print issue of Archives of
Internal Medicine, one of the JAMA/Archives journals.
Current estimates suggest smoking is responsible for several million
deaths per year from causes such as heart disease and cancer, according
to background information in the report. 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 write.
Minna Rusanen, M.D., of University of Eastern Finland and Kuopio
University Hospital, Kuopio, Finland, and colleagues analyzed data from
21,123 members of one health care system who participated in a survey
between 1978 and 1985, when they were 50 to 60 years old. Diagnoses of
dementia, Alzheimer's disease and vascular dementia were tracked from
Jan. 1, 1994 (when participants were an average of 71.6 years old),
through July 31, 2008.
A
total of 5,367 participants (25.4 percent) were diagnosed with dementia
during an average of 23 years of follow-up, including 1,136 with
Alzheimer's disease and 416 with vascular dementia.
Those who smoked more than two packs per day in middle age had an
elevated risk of dementia overall and also of each subtype, Alzheimer's
disease and vascular dementia, compared with non-smokers. Former
smokers, or those who smoked less than half a pack per day, did not
appear to be at increased risk.
Associations between smoking and dementia did not vary by race or sex.
Smoking is a well-established risk factor for stroke, and may contribute
to the risk of vascular dementia through similar mechanisms, the authors
note.
In
addition, smoking contributes to oxidative stress and inflammation,
believed to be important in the development of Alzheimer's disease. "It
is possible that smoking affects the development of dementia via
vascular and neurodegenerative pathways," the authors write.
"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," the researchers say.
"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. The large detrimental impact that smoking
already has on public health has the potential to become even greater as
the population worldwide ages and dementia prevalence increases."
The study was supported by The National Graduate School of Clinical
Investigation, EVO grants from Kuopio University Hospital, and grants
from the Juho Vainio Foundation and Maire Taponen Foundation. This study
was also supported by a Kaiser Permanente Community Benefits Grant and
National Institute of Health and Academy of Finland Grant.
