Dentists who treat obstructive sleep apnoea should be aware of new research linking depression and OSA in men, reports Frank Leggett
Men with undiagnosed obstructive sleep apnoea (OSA) have a strong association with depression, according to a study conducted by Dr Carol Lang, a research fellow in the Department of Medicine at the University of Adelaide. “OSA is also a very important issue in women,” says Lang, “but our research was initially set up to look at men’s health.”
A random sample of men who had not previously been diagnosed with OSA were asked to undertake a sleep study. In the community, OSA is undiagnosed in 82 per cent of men and 93 per cent of women, so Lang was particularly interested in those individuals who were unaware they had the condition.
OSA is a disorder where the airway is repeatedly blocked by the collapse of the back of the throat during sleep. The most common symptom is snoring and it’s often the partner of the sufferer who brings it to their attention. Other indicators of OSA include daytime drowsiness, headaches, lack of concentration, impotence and dry
mouth upon waking. In severe cases, it can lead to high blood-pressure, stroke and diabetes.
The condition affects men more frequently than women and is aggravated if the sufferer is overweight, smokes, drinks alcohol to excess or is over the age of 55, although it can occur at all ages.
The severity of those suffering from OSA is defined using the Apnoea-Hypopnoea index (AHI). The index measures how often a person pauses breathing per hour.
Men who score 30 or above on the AHI—classified as severe—have a greater chance of having depression. What remains unclear is whether depression is a byproduct of sleep apnoea, or whether people who are depressed are more likely to have OSA.
“Our research has revealed there is an association but we can’t tell if there is a direction to that,” says Dr Lang. “We know that many of the symptoms of OSA and depression overlap, such as feeling fatigued, not being able to sleep at night, and daytime sleepiness.
“The rate of depression in the general population is around five to six per cent. In sleep apnoea patients, it’s 20 to 25 per cent. The link is clear; there’s a higher chance of having a depressive illness if you suffer from OSA.”
Severe OSA is sometimes treated with a device called a CPAP (continuous positive airway pressure). This comprises a mask worn at night while a pump administers increased air pressure to keep the airway open. However, the most common and popular form of treatment is the mandibular advancement splint (MAS). This device pushes the lower jaw forward in order to make more space for breathing. Each splint is custom-made, so return appointments are required to fit them properly.
More and more dentists are treating patients for OSA, so it’s important they are aware of the link with depression. The classic OSA sufferer—a middle-aged, overweight man who’s very tired or falling asleep during the day—needs to be effectively treated for OSA, of course, but should also be informed of the association with depression.
“We have to get the message out there that snoring isn’t normal,” says Dr Lang. “Receiving effective treatment for OSA will benefit your physical health and could lead to an improvement in your mental state if depression is also diagnosed.”
Dr Darryl Moses, practice principal of Align Dental in Pennant Hills, NSW, has been treating OSA for eight years, and is currently completing the Master of Science in Sleep Medicine program at the University of Sydney. He has seen the impact the condition has on sufferers and how correct treatment improves their quality of life.
“When a patient presents with suspected OSA, the first step is to refer them for a sleep study,” says Dr Moses. “The diagnosis can’t be made by a dentist or a general medical practitioner. An increasing number of patients are undertaking an overnight sleep study in their own home by simply attaching specialised equipment when they go to bed. A report is then generated with a diagnosis made by a sleep physician.”
Once the sleep study is completed, there are many different factors that need to be assessed. These include the patient’s AHI, Respiratory-Disturbance Index, BMI and oxygen saturation levels. There are many questions that have to be answered with each study: is the apnoea worse during REM sleep? Is there a body position problem? What does the hypnogram show?
“In our practice, we also take a cone beam CT of the patient and very commonly work with ENT surgeons to see if there are any nasal airway problems,” says Dr Moses.
While CPAP is considered the most efficacious treatment of OSA, there is one big problem associated with it: patients don’t like wearing the mask attached to the pump, which means that CPAP has a much lower compliance rate than MAS.
“There are a range of MAS appliances available but the majority require the dentist to take an impression and a bite record,” says Dr Moses. “These records are then sent to a laboratory where the device is manufactured. We use SomnoMed devices as the company is continually partaking in clinical research to support its use. We’ve had very good results over a long period of time.”
Dr Moses agrees that all dentists should be aware of the link between depression and OSA.
“As a treating practitioner, it’s something that you need to keep in mind. OSA can lead to depression particularly due to sleep disturbances, but depression may also contribute to the development of OSA.”
Dr Moses has one final piece of advice: “Treating OSA can certainly increase your revenue base but one needs to understand that it is a serious medical problem. Treatment is not straightforward—diagnosis, treatment planning and ongoing patient-management are crucial. OSA is an insidious medical condition and each practitioner must have a good physiological understanding of what’s going on with each patient.”
With a link between OSA and depression now established, Dr Lang would like to see more awareness raised among sufferers. “It would be great if dentists had an OSA information pamphlet saying, ‘If you have sleep apnoea, you have a higher chance of also having depression, as well as other chronic conditions such as heart disease.’ Patients need to know that if they feel sad or empty or are losing interest in their family, work or pastimes they once enjoyed, then they should ask a doctor for an assessment.”
One of the best resources on depression is Beyond Blue. Patients who present with OSA would be well advised to visit its website, beyondblue.org.au, to get some background information on depression and address any concerns or questions they may have.