From: USA Today / October 26, 2010
Heavy smoking in midlife more
than doubles your odds of developing Alzheimer's disease, a Kaiser Permanente
study said Monday.
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.
Researchers evaluated the records
of 21,123 men and women, who, starting in midlife, were followed for an
average of 23 years. Of 5,367 study participants diagnosed with dementia
later in life, 2,367 were smokers, and 261 were heavy smokers (more than
two packs a day). Compared with non-smokers, those who had smoked two packs
of cigarettes a day increased their risk of developing Alzheimer's by more
than 157% and had a 172% higher risk of developing vascular dementia —
the second-most-common form of dementia after Alzheimer's. The research
is published online in the Archives of Internal Medicine (see abstract
Though the study was observational,
the authors have theories about what might be going on, Whitmer says. "People
who smoke have increased inflammation, and we know inflammation also plays
a role in Alzheimer's," she says.
Dementia experts say the new research
is strong. "This study is particularly good because it separates out vascular
dementia and Alzheimer's," says William Thies, the Alzheimer's Association's
chief medical and scientific officer.
"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, epidemiologist at Duke University Medical Center.
The bottom line: "If there's somebody
out there who hasn't heard smoking's bad for you, they must live in a cave
somewhere," Thies says. "This is another good reason not to smoke."
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,
Arch Intern Med. Published online
October 25, 2010. doi:10.1001/archinternmed.2010.393
Background Smoking is a risk
factor for several life-threatening diseases, but its long-term association
with dementia is controversial and somewhat understudied. Our objective
was to investigate the long-term association of amount of smoking in middle
age on the risk of dementia, Alzheimer disease (AD), and vascular dementia
(VaD) several decades later in a large, diverse population.
Methods We analyzed prospective
data from a multiethnic population-based cohort of 21 123 members of a
health care system who participated in a survey between 1978 and 1985.
Diagnoses of dementia, AD, and VaD made in internal medicine, neurology,
and neuropsychology were collected from January 1, 1994, to July 31, 2008.
Multivariate Cox proportional hazards models were used to investigate the
association between midlife smoking and risk of dementia, AD, and VaD.
Results A total of 5367 people
(25.4%) were diagnosed as having dementia (including 1136 cases of AD and
416 cases of VaD) during a mean follow-up period of 23 years. Results were
adjusted for age, sex, education, race, marital status, hypertension, hyperlipidemia,
body mass index, diabetes, heart disease, stroke, and alcohol use. Compared
with nonsmokers, those smoking more than 2 packs a day had an elevated
risk of dementia (adjusted hazard ratio [HR], 2.14; 95% CI, 1.65-2.78),
AD (adjusted HR, 2.57; 95% CI, 1.63-4.03), and VaD (adjusted HR, 2.72;
95% CI, 1.20-6.18).
Conclusions In this large
cohort, heavy smoking in midlife was associated with a greater than 100%
increase in risk of dementia, AD, and VaD more than 2 decades later. These
results suggest that the brain is not immune to long-term consequences
of heavy smoking.
Amy Jeffers, M.A., CPS
Regional Prevention Center Director