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New Research Could Reveal Why Depression Treatment Fails So Many

New research has stumbled across a finding that links sleep apnea to depression, and suggests the former may be one reason that depression treatments fail.

The initial purpose of a study at Augusta University in the U.S. was to discern whether treating patients' insomnia in addition to their depression reduced suicidal thoughts. Patients with sleep apnea were excluded from the study.

But when the 125 people enrolled were actually tested with a sleep study at home or in a sleep centre, investigators still found the condition in 17 -- it was undiagnosed sleep apnea.

"We were completely caught by surprise that people did not fit the picture of what obstructive sleep apnea is supposed to look like," said study lead and Chair of the Department of Psychiatry and Health Behavior at the Medical College of Georgia at Augusta University, Dr. William V. McCall.

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Around 20–30 percent of people with depression and other mood disorders do not get the help they need from existing therapies.

Therefore, many people with depression undergo a series of invasive and costly tests in an attempt to figure out the cause of depression treatment failure -- including MRI scans, carotid artery studies or even a spinal tap.

McCall says instead, treating sleep apnea with a continuous positive airway pressure (CPAP) machine may reduce the symptoms of depression.

Men are more likely to have sleep apnea. IMAGE: Getty Images

People with sleep apnea have repeated episodes of partial or complete obstruction of the throat (also known as the "pharynx" or "upper airway") during sleep.

"We know that patients with sleep apnea talk about depression symptoms," said McCall.

"We know that if you have obstructive sleep apnea, you are not going to respond well to an antidepressant.

We know that if you have sleep apnea and get CPAP, it gets better, and now we know that there are hidden cases of sleep apnea in people who are depressed and suicidal."

Most people with obstructive sleep apnea were in the upper end of the age range of 18 to 65, as sleep apnea and other sleep problems tend to increase with age.

Evidence has shown that patients who do not respond to one antidepressant are actually progressively less likely to respond to subsequent drugs that are tried.

He hopes that the team's new paper — appearing in The Journal of Psychiatric Research — will remedy this.

Antidepressants are commonly used to treat depression. IMAGE: Getty Images

The study authors also acknowledge that other factors — such as the side effects of other medications, including beta-blockers and corticosteroids — may cause treatment resistant depression.

Professor Ian Hickie, Co-Director of Health and Policy at The University of Sydney's Brain and Mind Centre told 10 daily these findings mirror similar studies undertaken in Australia.

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"This is a very active area of research at the moment," he said.

"Unrecognised sleep problems -- including sleep apnea -- are being found to have more links to mental illness than previously thought."

Professor Ian Hickie said mental illness diagnostics is too one-dimensional. IMAGE: Getty Images

He said it's a problem with the current narrow diagnostic criteria when it comes to mental illness.

"Currently we just want to put people in one box and individual diagnostic groups are limiting," he said.

Hickie said that mental health assessment and treatment is too one-dimensional.

It needs to be more sophisticated as it may not be therapy or antidepressants that are needed. You may just need to treat the sleep abnormality.

In any one year, around one million Australian adults have depression, and over two million have anxiety, according to Beyond Blue.

It is generally thought that around nine percent of women and 25 percent of men in Australia have clinically significant sleep anea.

Three million Australians are now reliant on antidepressants. 2019 data from the Pharmaceutical Benefits Scheme shows one in every eight Australians are using the drugs, including 100,000 children.

Contact the author alattouf@networkten.com.au