Memory
Decline, Alzheimer's Risk Linked To Diabetes
Early Study Provides
Clues
According to a study
reported in the Archives of Neurology, diabetes
may affect a person's cognitive abilities, and may increase
the risk for developing Alzheimer's disease (AD).
The findings, from
the Rush Alzheimer's Disease Center's Religious Orders Study,
add to a developing body of research examining a possible link
between diabetes and cognitive decline.
Diabetes is a serious
chronic disease that can be managed through lifestyle changes
and medication. Over 18 million US adults have diabetes,
and another 41 million adults ages 40 to 74 have pre-diabetes.
Diabetes Associated With
Other Diseases
The National
Diabetes Education Program describes diabetes as a
chronic disease in which the body does not produce or properly
use insulin, a hormone that is needed to convert sugar, starches,
and other food into energy. As a result, people with diabetes
have higher than normal blood glucose (sugar) levels.
If left uncontrolled,
diabetes causes serious complications, including heart disease,
stroke, vision loss, kidney disease, nerve damage, and lower
limb amputations.
The new study is
among the first to examine how certain cognitive "systems" -
memory for words and events, the speed of processing information,
and the ability to recognize spatial patterns - may be affected
selectively in people with diabetes.
The research was conducted
by Dr. Zoe Arvanitakis, Dr. David Bennett, and colleagues at
the Rush University Medical Center in Chicago and funded by National
Institute on Aging (NIA) at the National Institutes
of Health (NIH).
The AD Center at Rush
is one of 30 across the US supported by the NIA
to study and care for Alzheimer's patients.
"The research on a
possible link between diabetes and increased risk of AD is intriguing,
and this study gives us important additional insights," says
Dr. Neil Buckholtz, head of the Dementias of Aging Branch in
the NIA neurosciences program. "Further research,
some currently underway, will tell us whether therapies for
diabetes may in fact play a role in lowering risk of AD or cognitive
decline."
Study
Finds Diabetes, Alzheimer's Link
For an average of
5.5 years, the Rush scientists followed 824 Catholic nuns, priests,
and brothers who are taking part in the Religious
Orders Study.
The participants received
detailed clinical evaluations annually, including neuropsychological
testing of five cognitive "systems" commonly affected by aging,
AD, and other dementias (a brain disorder that affects a person's
ability to carry out daily activities).
The areas studied
included episodic memory (memory of specific life events),
semantic memory (general knowledge), working memory (ability
to hold and mentally rearrange information), perceptual speed
(the speed with which simple perceptual comparisons can be made,
such as whether two strings of numbers are the same or different),
and visuospatial ability (the ability to recognize spatial patterns).
Over the study period,
151 of the participants had a clinical diagnosis of AD, including
31 who had diabetes. The researchers found a 65 percent increase
in the risk of developing AD among those with diabetes compared
with people who did not have diabetes.
"We found that diabetes
was related to decline in some cognitive systems but not in
others," says Dr. Arvanitakis. "This study represents a continuation
of our research on possible risk factors for Alzheimer's disease."
In measures of cognitive
function, perceptual speed was associated with an increased
rate of decline over time, by about 44 percent, when comparing
the diabetes and non-diabetes groups.
In other areas of
cognition, the rate of change over the time period of the study
was no different in the two groups.
However, the researchers
state that at the beginning of the study the cognitive function
scores of people with diabetes were lower than those of people
without diabetes.
Stroke-related changes
in the brain were found in a previous study to be tied to a
decline in perceptual speed. The researchers could not say whether
the link between cognitive decline and diabetes appeared because
of the changes in the brain associated with Alzheimer's disease
or those of some other common age-related condition like stroke
or other vascular complications.
Studies looking at
pathological or brain imaging data would be needed to address
these possibilities.
"Researchers have
not yet found a cure for Alzheimer's disease, but if we can
identify factors that influence one’s risk of developing
Alzheimer's disease, this may allow us to make progress towards
identifying factors that decrease the risk of Alzheimer's disease," Dr.
Arvanitakis says.
Always consult your
physician for more information.
Online
Resources
(Our Organization
is not responsible for the content of Internet sites.)
American
Diabetes Association
Centers
for Disease Control and Prevention (CDC)
HealthierUS.Gov
National
Diabetes Education Program
National
Diabetes Information Clearinghouse
National
Institute of Diabetes & Digestive & Kidney Diseases
National
Institute of Neurological Disorders & Stroke
National
Institutes of Health (NIH)
National
Institute on Aging
National
Library of Medicine |
July 2004
Memory
Decline, Alzheimer's Risk Linked To Diabetes
Diabetes
Associated With Other Diseases
Study
Finds Diabetes, Alzheimer's Link
Alzheimer's
Disease Facts
Online
Resources
Alzheimer's
Disease Facts
Experts estimate that
up to 4 million US adults suffer from Alzheimer's
disease (AD). The disease usually begins after age 60, and risk
goes up with age.
While younger people
also may get AD, it is much less common. About 3 percent of
men and women ages 65 to 74 have AD, and nearly half of those
age 85 and older may have the disease.
It is important to
note, however, that AD is not a normal part of aging.
The most common form
of dementia (a brain disorder that seriously affects a person's
ability to carry out daily activities) is AD.
AD involves the parts
of the brain that control thought, memory, and language.
Although scientists
are learning more every day, currently they still do not
know what causes AD, and there is no cure.
Scientists do not yet fully understand what causes AD.
The National
Institute on Aging (NIA) states that there probably
is not one single cause, but several factors that affect each
person differently.
Age is the most important
known risk factor for AD. The number of people with the disease
doubles every five years beyond age 65.
Family history is
another risk factor. Scientists believe that genetics may play
a role in many AD cases. For example, familial AD, a rare form
of AD that usually occurs between the ages of 30 and 60, is
inherited.
The more common form
of AD is known as late-onset. It occurs later in life, and no
obvious inheritance pattern is seen.
However, several risk
factor genes may interact with each other to cause the disease.
The only risk factor gene identified so far for late-onset AD,
is a gene that makes one form of a protein called apolipoprotein
E (apoE).
Everyone has apoE,
which helps carry cholesterol in the blood. It is likely that
other genes also may increase the risk of AD or protect against
AD, but they remain to be discovered.
The NIA
is sponsoring the AD Genetics Initiative to
recruit families with AD to learn more about risk factor genes.
Scientists still need
to learn a lot more about what causes AD. In addition to genetics
and apoE, they are studying education, diet, and environment
to learn what role they might play in the development of this
disease.
Scientists are finding
increasing evidence that some of the risk factors for heart
disease and stroke, such as high blood pressure, high cholesterol,
and low levels of the vitamin folate, may predispose people
to AD.
Evidence for physical,
mental, and social activities as protective factors against
AD is also increasing.
The NIA
points out that AD begins slowly. At first, the only symptom
may be mild forgetfulness. In this stage, people may have trouble
remembering recent events, activities, or the names of familiar
people or things.
They may not be able
to solve simple math problems. Such difficulties may be a bother,
but usually they are not serious enough to cause alarm.
However, as the disease
goes on, symptoms are more easily noticed and become serious
enough to cause people with AD or their family members to seek
medical help.
For example, people
in the middle stages of AD may forget how to do simple tasks,
like brushing their teeth or combing their hair. They can no
longer think clearly. They begin to have problems speaking,
understanding, reading, or writing.
Later on, people with
AD may become anxious or aggressive, or wander away from home.
Eventually, patients need total care.
Always consult your
physician for more information. |
