TUESDAY, April 26 (HealthDay News) -- Seniors who are
"housebound" seem to have nearly double the risk of developing
Alzheimer's disease, a new study suggests.
The research doesn't prove that being confined to the house
causes dementia, and other factors could explain the association.
Still, the findings raise questions about the possible cost of
isolation, said lead investigator Bryan D. James, a postdoctoral
fellow at Rush Alzheimer's Disease Center in Chicago.
"People who don't leave their home as much aren't engaging with their environment and meeting new people," James said. "They may not be using their minds as much."
But James and his colleagues noted that underlying brain disease
may also explain the results -- that is, people may not be getting
out as much because the insidious workings of Alzheimer's or
another form of dementia may affect the way one moves through the
world long before they affect memory or speech.
Alzheimer's disease afflicts an estimated 5.2 million people in
the United States. That number is expected to grow to as many as
7.7 million Americans by 2030 as the Baby Boom generation ages.
The new study, published online April 15 in the
American Journal of Geriatric Psychiatry, looks at something known as "life space."
"[Life space] is actually a measure that has come into vogue with gerontologists lately," James said. "Mostly it's been a measurement of mobility, figuring out whether people are getting around their environment, how much they're seeing that's different from their couch or bedroom or living room."
Researchers followed 1,294 seniors from two separate studies of
older adults whose health was being tracked over time. At the
beginning of this study, none of the elders showed signs of
dementia. Over an average of 4.4 years, 180 developed Alzheimer's
disease.
The researchers found that people who reported that they never
left their home environment during a given week were about twice as
likely to develop Alzheimer's disease in the five years of
follow-up as those who traveled out of town. The research, James
said, offers "a new way to see who's going to be more likely to
develop dementia in the future."
The study also found that those who did not go beyond their
driveway or front yard were also more likely to develop mild
cognitive disorder, which can be an early manifestation of
Alzheimer's.
There are some caveats to the research. Some of the participants
lived in retirement homes and may have led full lives without
needing to leave the buildings where they live; however, they were
still counted as being housebound.
Still, the researchers found that the connection between
isolation and Alzheimer's disease remained even when they adjusted
their statistics so they wouldn't be thrown off by factors such as
depression, social networks, disease and disability, as well as
age, sex, education, race or preclinical dementia.
Why does all this matter? "People are interested in figuring out
who's going to develop Alzheimer's and new ways to target more
people likely to develop it," James said. "Maybe with the limited
interventions we do have available, we can target them toward
people who aren't leaving their homes."
Dr. James R. Burke, director of the Memory Disorders Clinic at
Duke University Medical Center, said isolation could offer a clue
to possible dementia problems before they become obvious. "This
will be particularly important when disease-modifying therapies are
available, so that evaluations can be started and interventions
considered before there are significant cognitive problems," Burke
said.
"This paper is consistent with, but extends, previous findings that physical activity, intellectual engagement and social stimulation are important to delaying cognitive decline," Burke added.
More information
For more about
Alzheimer's disease, visit the U.S. National Institute of Neurological Disorders and Stroke.