Mild cognitive
impairment prevalent in elderly population
Newswise — Mayo Clinic
researchers have found that mild cognitive impairment, a
disorder considered a strong early predictor of
Alzheimer’s disease, is prevalent among the elderly and
increases with age and fewer years of education.
Findings from this
study, funded by the National Institute on Aging, will
be presented Tuesday, April 4, at the American Academy
of Neurology meeting in San Diego.
The researchers
randomly selected 3,957 people from the general
population of Olmsted County, Minn., home of Mayo
Clinic, for participation in this study. The researchers
set out to find how many of those who did not have
dementia might have mild cognitive impairment. To date,
1,116 people without dementia in the study have been
evaluated.
The findings suggest
that 12 percent of 70- to 89-year-olds in Olmsted
County, Minn., have mild cognitive impairment. The
prevalence of mild cognitive impairment increased with
age, affecting 9 percent of those 70 to 79 and nearly 18
percent of those 80 to 89. The prevalence of mild
cognitive impairment also varied according to years of
education, ranging from 25 percent in those with up to
eight years of education, 14 percent in those with nine
to 12 years, 9 percent in those with 13 to 16 years, and
8.5 percent in those with greater than 16 years.
The researchers
suggest that the increase of mild cognitive impairment
with age found in this study parallels the risk
elevation with age seen in previous studies of
Alzheimer’s disease.
“This means that 12
percent to 20 percent of the entire population of those
over age 70 may have either mild cognitive impairment or
dementia, which is quite significant,” says Ronald
Petersen, M.D., Ph.D., Mayo Clinic neurologist and study
investigator. “These data have major implications for
the future of the health care system and the aging of
America.”
Dr. Petersen adds that
the increased risk for mild cognitive impairment with
fewer years of education found in this study parallels
other studies’ findings of a similar rise in risk for
Alzheimer’s disease as years of education decrease.
“People with more
years of education also may experience a loss of
cognitive ability, but they can compensate better and
thus they don’t demonstrate the symptoms of mild
cognitive impairment,” says Rosebud Roberts, M.B.Ch.B.,
Mayo Clinic epidemiologist and lead study investigator.
“It’s as though their education protects them from
exhibiting the effects of mild cognitive impairment.”
Dr. Petersen explains
that mild cognitive impairment is “the transitional
stage between normal aging and dementia.” This condition
may encompass deficiencies in any or all of the
following categories:
* Language --words
don’t come as quickly as they once did
* Visuospatial ability
--placement of things in time and space becomes more
difficult, such as having trouble getting the
proportions right when drawing a box
* Executive function
--decision making becomes more challenging
* Memory --recent
recall diminishes, such as what one did yesterday
Patients with mild
cognitive impairment otherwise function normally in
society, indicates
Dr. Roberts. In fact, she explains, the symptoms of mild
cognitive impairment can be so subtle that they are
difficult to detect unless living with the affected
person.
The current research
findings are preliminary; an additional 800 to 900
people will be evaluated before the study’s completion.
Mayo Clinic’s long-term hope with this research,
according to Dr. Roberts, is to identify factors that
protect against mild cognitive impairment and help
develop treatments for those affected, thus minimizing
the likelihood of progression to Alzheimer’s disease.