Even mild cognitive impairment appears to
substantially increase risk for death
September 6, 2011– Cognitive impairment,
even when detected at an early, mild stage,
is a significant predictor of decreased life
According to a new, long-term study from
Regenstrief Institute and Indiana University
researchers, cognitive impairment,
especially at the moderate to severe stages
has an impact on life expectancy similar to
chronic conditions such as diabetes or
chronic heart failure. Their findings,
"Cognitive Impairment: An Independent
Predictor of Excess Mortality. A Cohort
Study" appears in the Sept. 6, 2011 issue
of Annals of Internal Medicine.
Nearly 4,000 people between the ages of 60
to 102 years, initially seen from 1991 to
1993 by primary care physicians at Wishard
Health Services, a large public hospital
with community health centers in
Indianapolis, participated in the study. The
patients were followed for 13 years.
"Previous studies have associated cognitive
impairment with an increased risk for death,
but most of this work focused on patients
with Alzheimer disease and subjects in
research centers. The patients in our study
better reflect the general public,
displaying no indications of disease or
mild, moderate or severe cognitive
impairment," said Regenstrief investigator
Greg A. Sachs, M.D., professor of medicine
at the Indiana University School of
Medicine, where he is the division chief of
general internal medicine and geriatrics.
"We found that even mild cognitive
impairment, as determined by a simple
screening tool in a primary care physician's
office, has a strong impact on how long
individuals survive on the same order as
other chronic diseases."
The study followed 3,957 patients. At
screening, 3,157 had no cognitive
impairment, 533 had mild impairment, and 267
had moderate to severe impairment. During
follow-up, 57 percent of patients with no
impairment died, compared with 68 percent of
those with mild impairment and 79 percent of
those with moderate to severe impairment.
Median survival time was 138 months for
patients with no impairment, 106 months for
those with mild impairment, and 63 months
for those with moderate to severe
Study participants were screened for
cognitive impairment using an
easy-to-administer 10-question mental status
questionnaire. On the basis of the number of
errors patients made on this test, they were
categorized as having no, mild, or moderate
to severe cognitive impairment. The
Regenstrief Medical Record System was used
to obtain data on the patients' medical
conditions, results of lab tests and other
Cognitive impairment affects memory and
thinking. Approximately 4 million to 5
million people in the United States have
dementia, and the number of individuals
affected is significantly higher if
individuals with milder forms of cognitive
impairment are included. The prevalence of
cognitive impairment at all stages is
expected to increase as the population ages.
The study findings have important clinical
and prognostic implications beyond dementia
detection, treatment and support for
affected patients and their families.
Reduced life expectancy in patients with
cognitive impairment should be factored into
medical decisions, such as advance care
planning, cancer screening and prescribing
of medications, especially in patients with
severe impairment, the authors state.
Given that the magnitude of the risk of mild
and moderate to severe cognitive impairment
is similar to that of many life-limiting
diseases, as well as the ease of
indentifying cognitive impairment by using a
short screening tool, recognition of
cognitive impairment in primary care
practices should be given a higher priority,
the study concludes.
Authors are Greg A. Sachs, M.D.; Wanzhu Tu,
Ph.D. and Christopher M. Callahan, M.D. of
the Regenstrief Institute and IU School of
Medicine; Ravan Carter, M.A.; Laura R.
Holtz, B.S., CCRP and Faye Smith, M.A., of
the Regenstrief Institute, and Timothy E.
Stump, M.A. of the IU School of Medicine.
The study was supported by the Agency for
Healthcare Research and Quality.