Sleep-Disordered Breathing may increase risk
of Cognitive Impairment, Dementia among
Older Women
Newswise, August 10, 2011— Older women with
sleep-disordered breathing, as indicated by
measures of hypoxia (oxygen deficiency),
were more likely to develop cognitive
impairment or dementia than women without
this disorder, according to a study in the
August 10 issue of JAMA.
"Sleep-disordered breathing, a disorder
characterized by recurrent arousals from
sleep and intermittent hypoxemia, is common
among older adults and affects up to 60
percent of elderly populations. A number of
adverse health outcomes including
hypertension, cardiovascular disease, and
diabetes have been associated with
sleep-disordered breathing," according to
background information in the article.
"
Cognitive impairment also has been linked to
sleep-disordered breathing in some studies,
but the design of most of these studies has
limited the ability to draw conclusions
regarding this association.
"Given the high prevalence and significant
morbidity associated with both
sleep-disordered breathing and cognitive
impairment in older populations,
establishing whether a prospective
association exists between sleep-disordered
breathing and cognition is important. This
is especially important because effective
treatments for sleep-disordered breathing
exist."
Kristine Yaffe, M.D., of the University of
California, San Francisco, and colleagues
examined the association between prevalent
sleep-disordered breathing as measured with
polysomnography (monitoring of physiological
activity during sleep) and subsequent
diagnoses of mild cognitive impairment and
dementia. The study included 298 women
without dementia at the beginning of the
study (average age, 82.3 years) who had
overnight polysomnography measured between
January 2002 and April 2004 in a substudy of
the Study of Osteoporotic Fractures.
Sleep-disordered breathing was defined as an
apnea-hypopnea index of 15 or more events
per hour of sleep. The apnea-hypopnea index
is the number of complete cessations (apnea)
and partial obstructions (hypopnea) of
breathing occurring per hour of sleep.
Cognitive status (normal, dementia, or mild
cognitive impairment) was based on data
collected between November 2006 and
September 2008. Measures of hypoxia, sleep
fragmentation, and sleep duration were
investigated as underlying mechanisms for
any association between sleep-disordered
breathing and cognitive impairment.
Among the 298 women, 35.2 percent met
criteria for sleep-disordered breathing.
After an average of 4.7 years of follow-up,
35.9 percent of the women developed mild
cognitive impairment or dementia (mild
cognitive impairment: 20.1 percent;
dementia: 15.8 percent). Forty-seven women
(44.8 percent) with prevalent
sleep-disordered breathing developed mild
cognitive impairment or dementia compared
with 31.1 percent of those without
sleep-disordered breathing. Analysis of the
data indicated that the presence of
sleep-disordered breathing was associated
with an increased odds of subsequent mild
cognitive impairment or dementia.
The researchers also found, after adjusting
for various demographic risk factors, that
two measures of hypoxia (an oxygen
desaturation index of 15 or greater and a
high percentage of total sleep time [greater
than 7 percent] in apnea or hypopnea) were
associated with higher incidence of mild
cognitive impairment or dementia. "Measures
of sleep fragmentation (arousal index and
wake after sleep onset) or sleep duration
(total sleep time) were not associated with
risk of cognitive impairment." The authors
add that their finding that sleep-disordered
breathing was associated with an increased
risk of cognitive impairment seems to be
related primarily to measures of hypoxia.
"Given the high prevalence of both
sleep-disordered breathing and cognitive
impairment among older adults, the
possibility of an association between the 2
conditions, even a modest one, has the
potential for a large public health impact.
Furthermore, the finding that hypoxia and
not sleep fragmentation or duration seems to
be associated with risk of mild cognitive
impairment or dementia provides clues to the
mechanisms through which sleep-disordered
breathing might promote cognitive
impairment. The increased risk for cognitive
impairment associated with sleep-disordered
breathing opens a new avenue for additional
research on the risk for development of mild
cognitive impairment or dementia and
exploration of preventive strategies that
target sleep quality including
sleep-disordered breathing," the researchers
write.
They add that to fully evaluate the impact
of treatment for sleep-disordered breathing
in elderly populations, additional trials
with larger sample sizes, longer treatment
periods, and more diverse populations are
required. "Of interest, our findings suggest
a potential role for supplemental oxygen
therapy for sleep-disordered breathing in
elderly individuals; however, its role
requires critical evaluation in intervention
studies."
Editor's Note: Please see the article for
additional information, including other
authors, author contributions and
affiliations, financial disclosures, funding
and support, etc.
Editorial: Sleep-Disordered Breathing and
Cognitive Decline in Older Adults
In an accompanying editorial, Nicola Canessa,
Ph.D., of the Center for Cognitive
Neuroscience, and Luigi Ferini-Strambi,
M.D., of the Universita Vita-Salute San
Raffaele, Milan, Italy, write that "the
study by Yaffe et al and related studies to
date suggest that large trials with
continuous positive air pressure (CPAP)
treatment in elderly participants with
sleep-disordered breathing should be
performed."
"Moreover, in trials evaluating the effects
of pharmacological and nonpharmacological
(e.g., cognitive training and
rehabilitation) interventions on cognitive
function in patients with mild cognitive
impairment or dementia, the possible
coexistence of sleep-disordered breathing
should be considered. Finally, physicians of
patients with mild cognitive impairment and
sleep-disordered breathing for whom
treatment with CPAP may be indicated should
consider these results, and future
guidelines to formalize the clinical
management of patients with mild cognitive
impairment should consider the implications
of this study and related research."
