Understanding the Causes of Canker Sores
Although the specific cause of canker sores isn't known, dentists and doctors have noticed a few risk factors. For example, the U.S. Office on Women's Health points out that women tend to get canker sores more than men, so your biology may come into play. An injury inside the mouth, such as from biting the inside of your cheek or lip, may also increase your risk of developing a canker sore, as can emotional factors like stress and fatigue.
A few small studies have taken a look at the role anxiety and depression play in the development of canker sores or recurrent aphthous stomatitis (RAS), which are canker sores that form often. The Merck Manual estimates that RAS occurs in 20 to 30 percent of adults.
One study, published in the Journal of Oral Pathology and Medicine, evaluated the role of anxiety, psychological stress and depression on RAS. After giving participants a series of questionnaires and psychological tests, the researchers determined that there appeared to be a link between canker sore stress, depression and anxiety and the symptoms of this oral problem.
A second study, published in Contemporary Clinical Dentistry, evaluated the psychological profiles and salivary cortisol levels (which can indicate stress) of people with RAS. Although the study was small, researchers were able to draw the conclusion that levels of anxiety and depression were higher in people with RAS than in the control group.