A Natural Remedy for Depression - Alleviating Sleep Apnea?

Could correcting sleep apnea remedy depression? Studies link sleep apnea and depression, therefore the correction of sleep apnea may be a remedy for depression. For more than twenty years studies have suggested the existence of a relationship between depression and obstructive sleep apnea in the general population.

A researcher at Stanford University found that in the general population of the United Kingdom, Germany, Italy, Portugal, and Spain about 800 of 100,000 individuals have both a breathing-related sleep disorder and a major depressive disorder with nearly 20% of the subjects who had one of these disorders also having the other. (J Clin Psychiatry 2003, 64:1195-200; quiz, 1274-6).

In clinical practice, the presence of depressive symptoms is often considered in patients with obstructive sleep apnea although sleep problems and specifically obstructive sleep apnea are rarely assessed on a regular basis in patients with a depressive disorder.

It is speculated that obstructive sleep apnea might not only be associated with a depressive syndrome, but its presence may also be responsible for failure to respond to pharmacological treatment and that undiagnosed obstructive sleep apnea might be exacerbated by antidepressant medications, such as benzodiazepines.

Although the benzodiazepines (central nervous system depressant drugs) may reduce sleep fragmentation, their long-term use may also cause health problems, such as complete obstructive sleep apnea in heavy snorers…(Am J Med. 1990 Mar 2;88(3A):25S-28S).

Obstructive sleep apnea is the most common form of sleep disordered breathing and is defined by frequent episodes of obstructed breathing during sleep. It is characterized by sleep-related decreases or pauses in respiration.

The prevalence of obstructive sleep apnea is higher in men than in women and is found in all age groups but its prevalence increases with age. In children, the prevalence of obstructive sleep apnea is less well known and has been estimated to be between 2-8%.

The estimated prevalence of sleep-disordered breathing in people between the ages of 30 to 60 years old was 9 percent for women and 24 percent for men. Male sex and obesity were strongly associated with the presence of sleep-disordered breathing. (N Engl J Med. 1993 Apr 29;328(17):1230-5).

Abnormal respiratory events are the hallmark of obstructive sleep apnea and are generally accompanied by heart rate variability and arousals from sleep, with frequent arousals being the most important factor resulting in excessive daytime sleepiness.

The extent to which daytime functioning is affected generally depends on the severity of obstructive sleep apnea. Symptoms other than excessive daytime sleepiness which greatly impact daytime functioning are neuropsychological symptoms such as irritability, difficulty concentrating, cognitive impairment, depressive symptoms, and other psychological disturbances. Therefore obstructive sleep apnea can easily mimic symptoms of a major depressive episode.

In 1997 researchers studied the relation between obstructive sleep apnea and depression and reported that 24% of 25 male patients with obstructive sleep apnea had previously seen a psychiatrist for anxiety or depression. (Arch Intern Med. 1977 Mar;137(3):296-300).

In 1989 researchers at the University of California Irvine Medical Center, found 67% of patients who presented to a major sleep disorders center reported an episode of depression within the previous 5 years, and 26% described themselves as depressed at presentation. (J Clin Psychol. 1989 Jan;45(1):51-60).

Of 50 patients who had severe obstructive sleep apnea most patients showed cognitive impairment; 76% had suspected or mild to severe deficits in terms of thinking, perception, memory, communication, or the ability to learn new information, resulting in a greater potential for being distractible, confused, and irritable. (J Chronic Dis. 1985;38(5):427-34).

In 1992 researchers in Spain found elevations in several depression scores in 23 obstructive sleep apnea patients (moderate to high severity) compared to 17 controls. Depression, schizophrenia, and hypochondriasis [chronic and abnormal anxiety about imaginary symptoms and ailments] were the highest scales. (Int J Neurosci. 1992 Feb;62(3-4):173-95).

Compared to patients who snore but do not have apnea, those with obstructive sleep apnea have more intense depressive symptoms (e.g., pessimism, inactivity, guilt) and somatic [physical] concerns. However, patients who snore but do not have apnea show psychological maladjustment that is in quality similar, but in quantity less severe, than those with obstructive sleep apnea. (Sleep. 1999 May 1;22(3):355-9).

Contradictory Research with Due to Limitations:

Researchers at the University of Kentucky, Department of Medicine, conducted a 5-year study of 95 normal older persons and did not find any significant depressive symptoms in elderly patients with a relatively mild obstructive sleep apnea, when compared to a control group without obstructive sleep apnea. (Chest. 1996 Sep;110(3):654-8).

However, there are multiple limitations to this study, besides a relatively small sample size for group comparisons and a non-representative study population.

Obstructive sleep apnea was only assessed at the start of the study, but not repeated at the five-year follow-up, i.e. neuropsychological data were compared between two groups based on obstructive sleep apnea status five years earlier.

Second, obstructive sleep apnea severity was mild even in the obstructive sleep apnea group.

Third, the groups differed significantly by age, with the obstructive sleep apnea group being older than the control group.

Finally, the drop out rate over the five years was very high with only 42 out of the initial 95 subjects completing the follow-up assessment. (Annals of General Psychiatry 2005, 4:13).

In 1998 researchers in Israel conducted a study comprising 2,271 patients (1,977 men, 294 women) with suspected Sleep Apnea Syndrome. They did not observe any association between respiratory disturbances and Symptom Check List 90 psychiatric questionnaire. (Chest. 1998 Sep;114(3):697-703).

However, the SCL-90 psychiatric questionnaire was developed as a screening tool for psychiatric patients, and not for a normal study population. Therefore, it might be a less sensitive tool with regards to milder forms of mood disturbances than other scales. (Annals of General Psychiatry 2005, 4:13).

However, the researchers in the abovementioned study did observe that among the minority of women in the study, those with severe obstructive sleep apnea had higher depression scores than those with mild obstructive sleep apnea. (Chest. 1998 Sep;114(3):697-703).

Fewer studies have focused on the screening for obstructive sleep apnea in primarily depressed study groups.

Sleep apnea was found in 42.9% of demented patients, 17.6% of depressives, and 4.3% of controls. A significant association between sleep apnea and dementia of the Alzheimer type was found in women but not in men. Moreover, severity of dementia was significantly correlated with apnea index. (J Clin Psychiatry. 1985 Jul;46(7):257-61).

All of the above suggests that obstructive sleep apnea might be an important confounding factor for studies on mood disorders in general, as its presence is not routinely determined in either research studies examining mood or clinical settings.

More studies are required to assess the prevalence of obstructive sleep apnea in primarily depressed patients, particularly as it can be suspected from existing studies that obstructive sleep apnea is greatly under diagnosed in depressed patients.

Reference: Adapted from: Schröder CM, O'Hara R. Depression and Obstructive Sleep Apnea (OSA). Annals of General Psychiatry 2005, 4:13 (27 June 2005). Review. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0).

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