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Depression and
Sleep Apnea
Last edited |
10/25/2008
Some clinical studies have attempted to
determine whether depression limits the recognition and treatment of
breathing-related sleep disorders, or if breathing-related sleep disorders play
a role in the etiology or course of depressive disorder
The results of clinical studies have been mixed:
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Some were showing that
obstructive sleep apnea syndrome is associated with higher rates of clinical
depression (2, 3, 4) or higher rates of depressive symptomatology (5, 6).
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Other
clinical studies have found that obstructive sleep apnea patients do not have
higher rates of depression than do individuals with other chronic diseases (7)
or control subjects (8, 9).
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Some studies have also measured whether depressive symptomatology is lessened when a breathing-related sleep disorder is treated
with continuous positive airway pressure (CPAP) (6, 10). However, the
amelioration in the depressive mood could be due to a placebo effect of the CPAP
(10).
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One study that examined the sleep
architecture of depressive patients with obstructive sleep apnea syndrome found
that sleep latency was longer and the percentage of REM shorter in depressed
patients without obstructive sleep apnea compared to depressed patients with
obstructive sleep apnea (11).
Research
Data about
breathing-related sleep disorders and depressive illness were documented only to
a clinical level.
The importance of this
association in the general population remained undocumented until the
realization of this study.
Method
The studied countries were:
● The
United Kingdom,
● Germany,
● Italy,
● Portugal
●
and
Spain.
The target population was all non-institutionalized residents
aged 15 years or over with the exception of Portugal, where the minimum age was
set at 18 years.
This represented about 206 million Europeans.
A two-stage
design was used for all countries.
The population of each country was:
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First
divided according to its geographical distribution as
per the official census data, then telephone numbers were
randomly drawn in each geographical area.
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Second,
within each household,
a member was selected by age and gender using the Kish method (16) in order
to maintain the representation of the sample and to avoid
bias related to non-coverage error.
Participants had to first grant their verbal consent prior to
proceeding with the interview.
For subjects younger than 18 years of age, the
verbal consent of the parent(s) was also requested.
We excluded potential
participants who had insufficient fluency in the national language, who had a
hearing or speech impairment or with an illness that precluded the feasibility
of an interview.
The participation rate was:
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79.6% (4,972 of 6,249
eligible individuals) in the UK;
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68.1% (4,115 of 6,047
eligible individuals) in Germany;
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89.4% (3,970 of 4,442
eligible individuals) in Italy;
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83% (1,858 of 2,234
eligible subjects) in Portugal;
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and 87.5% (4,065 of
4,648 eligible individuals) in Spain.
A total of 18,980
subjects participated in the study. The overall participation rate was 80.4%.
Results
This
is the first time that an epidemiological study has attempted to estimate the
association between breathing-related sleep disorders and major depressive
disorders.
Our
results show that 0.8% of the general population have both disorders; this
represents about 800 individuals out of 100,000.
Comparison with other
community-based studies
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Obstructive sleep apnea
syndrome (OSAS)
Existing prevalence rates for OSAS
have been mainly derived from studies on cohorts or from selected samples (13,
28, 29) rather than from representative samples of the general population.
The
prevalence of OSAS observed in this sample is similar to the rate reported by
Young et al. (13) in the Wisconsin cohort when comparing the same age range.
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Major depressive disorders
In this study, the point prevalence of a DSM-IV major depressive episode
(4.3%) is comparable to the one-month prevalence reported in the National
Comorbidity Survey (NCS) (4.9%) (15).
However, this is higher than the prevalence
obtained in the Epidemiological Catchment Area (ECA) survey (2.2%) (14).
The
main difference is in the definition of major depressive episode.
In this
study, to include as much individuals with a major depressive
episode, we did not exclude individuals who also fulfilled the criteria for a
manic episode (like the NCS study did).
When we excluded the individuals with
substance abuse or dependence, bipolar disorders or non-affective psychosis,
the prevalence of a major depressive episode dropped to 2.4%, which is close
to the ECA rate and close also to the 2.1% rate of pure episode of major
depression reported in the NCS study.
Association between breathing-related sleep
disorders and major depressive disorders
We found a high positive association between major
depressive disorder and breathing-related sleep disorders:
depressive subjects
being five times more likely to have breathing-related sleep disorders than
non-depressed subjects.
This association remains strong and positive even when
controlling for other important factors such as obesity and hypertension.
This
result is different from a clinical study that found the association between a
breathing-related sleep disorder and depressive symptoms disappeared when
controlling for BMI and hypertension (30).
This can be due to the fact that
these authors measured only sleep apnea (respiratory disturbance index >=15
events per hours) and based the presence of depression on the CES-D scale.
The
contradiction found in the literature about the association between
breathing-related sleep disorders and depression can be related to the
definition used:
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Some studies used only the respiratory disturbance index as a
measure of the presence of a breathing-related sleep disorder.
However,
obstructive sleep apnea syndrome and breathing-related sleep disorders
diagnosis are more complex clinical entities that require the presence of
other clinical symptoms such as excessive daytime sleepiness or
non-restorative sleep, two symptoms that are often observed in depressed
patients.
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Other studies have attempted to relate the severity of the
breathing-related sleep disorder using the RDI to the presence of depression
(31).
The severity of the RDI did not appear related to the presence of
depression.
However, the severity of clinical symptoms of breathing-related
sleep disorders was not assessed.
The severity of fatigue or daytime
sleepiness associated with the breathing-related sleep disorder may have
influenced the presence of a depressive disorder.
We also found that psychotic features were
positively associated with breathing-related sleep disorders but not as
strongly as major depressive episodes.
The association remained even when
controlling for the presence of major depressive episodes.
These associations
have been seldom investigated although some cases have been reported (32,33).
In conclusion, nearly one
fifth of subjects with a breathing-related sleep disorder also have a major
depressive disorder and a similar proportion of individuals with depressive
disorder have a breathing-related sleep disorder.
The identification of one of these disorders
should prompt physicians to investigate for the presence of the other disorder.
Content of this page
is extracted from Ohayon MM,
The effects of breathing-related
sleep disorders on mood disturbances in the general
population.
J Clin Psychiatry. 2003 Oct;64(10):1195-200; quiz, 1274-6.
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Sleep-EVAL
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