Obstructive sleep apnea (OSA) is a risk factor for a number of health concerns,
particularly cardiovascular diseases and neurocognitive problems. Researchers say this association deserves a closer look.
One study involving nearly 19,000 randomly selected people in five European countries found nearly 1 in 5 people with depression also have sleep disorders, and vice-versa: nearly 20 percent with sleep disorders suffer from depression.
These results prompted other researchers to take a deeper look at the association between OSA and psychiatric symptoms. Their research was published in the Journal of Neurosciences in Rural Practice in 2017.
In the study, 182 individuals who were referred to a private hospital in India for a sleep study underwent overnight polysomnography (PSG) to assess the presence of sleep disordered breathing. Researchers also recorded any history of complaints such as snoring, nocturia, disturbed sleep, and morning headaches.
The study subjects also received psychiatric diagnoses,assessed using the Mini-International Neuropsychiatric Interview, followed by the Hamilton Depression Rating Scale, with confirmation by a consultant psychiatrist.
Researchers found that one-quarter of those who referred for the sleep studies — 47 people — were suffering from depression. Compared to participants without depression, these individuals:
- Were more likely to snore
- Were more likely to experience nocturia
- Experienced more disturbed sleep
- Experienced more daytime sleepiness
- Had poorer sleep efficiency
- Took longer to fall asleep
- Had more severe sleep apnea (as measured by the apnea–hypopnea index)
Why might OSA be associated with depression?
The symptoms of OSA may explain the link. The fragmented sleep and frequent drops in blood oxygen levels associated with untreated OSA can lead to hyperarousal, inflammation, and an increase in the levels of corticosteroids such as cortisol. The authors of the study argue that these effects can, in turn, lead to decreased mood and cognitive disorders.
That being said, depression is also a risk factor for OSA. Researchers suggested that the low serotonin levels associated with depression can lead to a decrease in muscle tone of the upper respiratory tract and increase the likelihood of sleep disordered breathing.
Why we should be concerned about a potential link
As noted by the study’s authors, depression in people with OSA has major consequences.
Studies have found that the gold standard for OSA treatment, continuous positive airway pressure (CPAP) may not improve depression or anxiety. This could be because long-term use of CPAP may generate anxiety and depression by itself, or it may be because patients recognize that CPAP merely treats the symptoms of their OSA and doesn’t cure it. This makes early diagnosis and treatment of depression even more important for those with OSA.
The importance of early diagnosis
The authors of the 2017 study point out that depression is often diagnosed late, since it is not always recognized as a condition associated with OSA. They argue that timely psychiatric intervention can help improve quality of life among those with OSA and suggest that regular screening of depression should be integrated into OSA management.
The authors also suggest that depressed individuals who regularly snore or notice pauses in breathing during sleep (sometimes characterized by an interruption in snoring followed by a snort) should be referred to a sleep clinic for PSG evaluation.
With all this being said, there is still a clear need for additional studies of OSA in individuals with depressive disorders to help evaluate the strength of any such link and to enhance our understanding of the relationship between the two conditions.