Alzheimer's, Dementia & Mental Health
Over Half of Alzheimer’s Cases May Be Preventable, Say Researchers
Study presented at Alzheimer's conference identifies key factors that can be modified to lower risk of AD
Deborah Barnes, PhD
July 20, 2011 - Over half of all Alzheimer’s disease cases could potentially be prevented through lifestyle changes and
treatment or prevention of chronic medical conditions, according to a study led by Deborah
Barnes, PhD, a mental health researcher at the San Francisco VA Medical Center (SFVAMC).
The research was presented yesterday at the Alzheimer's Association International Conference 2011 (AAIC 2011) in Paris.
The researchers reported the proportion of Alzheimer's cases worldwide that are potentially attributable to each of the
seven risk factors:
● low education 19 percent
● smoking 14 percent
● physical inactivity 13 percent
● depression 11 percent
● mid-life hypertension 5 percent
● mid-life obesity 2 percent
● diabetes 2 percent
And specifically in the U.S.:
● physical inactivity 21 percent
● depression 15 percent
● smoking 11 percent
● mid-life hypertension 8 percent
● mid-life obesity 7 percent
● low education 7 percent
● diabetes 3 percent
Together, the seven potentially modifiable risk factors contributed to roughly 50 percent of Alzheimer's cases worldwide
(51 percent, 17.2 million) and in the U.S. (54 percent, 2.9 million).
“What’s exciting is that this suggests that some very simple lifestyle changes, such as increasing physical activity and
quitting smoking, could have a tremendous impact on preventing Alzheimer’s and other dementias in the United States and worldwide,” said
Barnes, who is also an associate professor of psychiatry at the University of California, San Francisco (UCSF).
"We were surprised that lifestyle factors such as physical inactivity and smoking appear to contribute to a larger number
of Alzheimer's cases than cardiovascular diseases in our model," added Barnes.
"But this suggests that relatively simple lifestyle changes such as increasing physical activity and quitting smoking
could have a dramatic impact on the number of Alzheimer's cases over time."
According to Barnes' calculations, a 10 percent reduction in all seven risk factors could potentially prevent 1.1 million
Alzheimer's cases worldwide and 184,000 cases in the U.S. over time.
A 25 percent reduction in all seven risk factors could potentially prevent more than 3 million Alzheimer's cases
worldwide and 492,000 cases in the U.S. over time.
"In our study, what mattered most was how common the risk factors were in the population," said Barnes. "For example, in
the U.S., about one third of the population is sedentary, so a large number of Alzheimer's cases are potentially attributable to physical
Worldwide, low education was more important because literacy rates are lower or people are not educated beyond elementary
school. Smoking also contributed to a large percentage of cases because it is unfortunately still very common."
Barnes says the estimates make an important assumption – that there is a causal relationship between the risk factors
examined and Alzheimer's disease. "The next step is to perform large-scale intervention studies to really find out whether changing these risk
factors will lower the risk of developing Alzheimer's over time,"
Barnes cautioned that her conclusions are based on the assumption that there is a causal association between each risk
factor and Alzheimer’s disease.
“We are assuming that when you change the risk factor, then you change the risk,” Barnes said. “What we need to do now is
figure out whether that assumption is correct.”
Kristine Yaffe, MD, chief of geriatric psychiatry at SFVAMC, noted that the number
of people with Alzheimer’s disease is expected to triple over the next 40 years.
“It would be extremely significant if we could find out how to prevent even some of those cases,” said Yaffe, who is also
a professor of psychiatry, neurology and epidemiology at UCSF.
The research was supported by funds from the Alzheimer’s Association, the National Alliance for Research on Schizophrenia
and Depression, the UCSF School of Medicine and the National Institute on Aging.
SFVAMC has the largest medical research program in the national VA system, with more than 200 research scientists, all of
whom are faculty members at UCSF.
UCSF says it is a leading university dedicated to promoting health worldwide through advanced biomedical research,
graduate-level education in the life sciences and health professions, and excellence in patient care.
>> More about
Deborah Barnes, PhD
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