People who eat a "Mediterranean"
diet rich in fruits, vegetables, olive oil,
legumes, cereals and fish have a lower risk
of developing Alzheimer's
disease, U.S. researchers report.
"We have confirmed the association of
a Mediterranean diet with Alzheimer's disease,"
said lead researcher Dr. Nikolaos Scarmeas,
an assistant professor of neurology at Columbia
University Medical Center in New York.
This benefit does not appear to be due to
the diet's effect on blood vessels, Scarmeas
added. "The diet could be helping avoid
Alzheimer's disease by protection from oxidative
stress or by reducing inflammation in the
brain," he said.
Another study finds that taking omega-3 fatty
acid supplements slows cognitive decline in
some patients with very mild Alzheimer's disease.
However, supplements do not appear to affect
people with more advanced cases of the disease,
according to a team of Swedish researchers.
Both reports appear in the online October
issue of the Archives of Neurology.
For the diet study, Scarmeas's team collected
data on almost 2,000 people averaging 76 years
of age. Of these, 194 had developed Alzheimer's.
The researchers analyzed each person's diet
during the previous year and scored the diet
based on how closely it followed what's known
as the Mediterranean diet, which also includes
mild-to-moderate drinking and little intake
of red meat. Scores ranged from zero to 9.
Higher scores were given for closely following
a Mediterranean diet.
People who closely followed that regimen
had a significantly lower risk for Alzheimer's
disease, the researchers found. For each additional
point on the diet score, risk for Alzheimer's
was reduced by 19 to 24 percent.
In fact, people in the top one-third of diet
scores had 68 percent lower risk of developing
Alzheimer's disease, compared with people
in the bottom third. In addition, people in
the middle third had a 53 percent lower risk
of developing the disease.
While the jury is still out on whether a
Mediterranean diet actually protects people
from developing Alzheimer's disease, Scarmeas
believes that the other health benefits of
the diet are clear.
"It seems that this diet is [health]
protective," Scarmeas said. "Taking
into account that this diet is protective
for other conditions such as coronary heart
disease, heart attack, high blood pressure,
obesity and a series of cancers, it seems
to make sense to follow this diet anyway,
and the diet may also protect from Alzheimer's
disease."
In the second report, a team led by Dr. Yvonne
Freund-Levi from the Karolinska Institutet
in Stockholm, looked at the effects of omega-3
fatty acids supplements on 204 patients with
Alzheimer's disease.
After six months, among the 174 people who
completed the trial, the researchers found
no difference in cognitive decline among people
taking omega-3 fatty acids supplements at
different doses or placebo.
However, for a subgroup of 32 patients with
very mild cognitive impairment at the beginning
of the study, those taking the supplements
experienced less cognitive decline compared
with those who took placebo, the researchers
found.
And when patients who took placebo during
the first six months were given omega-3 fatty
acids supplements, their cognitive decline
decreased during the second six months of
the trial.
"The mechanisms by which omega-3 fatty
acids could interfere in Alzheimer's disease
pathophysiologic features are not clear, but
since anti-inflammatory effects are an important
part of the profile of fish oils, they are
conceivable also for Alzheimer's disease,"
the researchers write. "It is possible
that when the disease is clinically apparent,
the neuropathologic involvement is too advanced
to be substantially attenuated by anti-inflammatory
treatment."
One expert said that, given the other health
benefits of fish oil, it certainly can't hurt
patients to take supplements.
"I am happy to tell people that if they
want to reduce their risk for Alzheimer's,
they should reduce their cardiovascular disease
risk factors and take fish oil," said
Greg M. Cole, a neuroscientist at the Greater
Los Angeles VA Healthcare System, and the
associate director of the Alzheimer's Disease
Research Center at UCLA's David Geffen School
of Medicine.
A second expert agreed that diet probably
does influence the disease.
"The papers share a focus on the idea
that diet plays a role in Alzheimer's, a consensus
that has been building for the past five or
six years," said Dr. Sam Gandy, the chair
of the Medical and Scientific Advisory Council
at the Alzheimer's Association and director
of the Farber Institute for Neurosciences
at Thomas Jefferson University.
"The common thread is that both papers
point toward intervention at the earliest
moment having a greater effect and the suggestion
that prevention may have the greatest effect
of all," Gandy said.
"Once the gooey amyloid material has
accumulated and poisoned nerve cells and the
cells have died, it is very hard to think
seriously about repairing damage that severe,"
he added.
