Depression is more than simply feeling unhappy or fed up for a few days.
We all go through spells of feeling down, but when you're depressed, you feel persistently sad for weeks or months rather than just a few days.
Some people still think that depression is trivial and not a genuine health condition. They're wrong. Depression is a real illness with real symptoms, and it's not a sign of weakness or something you can 'snap out of' by 'pulling yourself together'.
The good news is that with the right treatment and support, most people can make a full recovery from depression.
Depression affects people in many different ways and can cause a wide variety of symptoms.
They range from lasting feelings of sadness and hopelessness to losing interest in the things you used to enjoy and feeling very tearful or anxious.
There can be physical symptoms too such as feeling constantly tired, sleeping badly, having no appetite or sex drive and complaining of various aches and pains.
An article published in the Journal of the Canadian Dental Association claims that many dentists are at risk of suffering from a chronic mood disorder known as dysthymia. It's a condition the Université de Montréal Department of Dentistry is fighting - preventively.
Dysthymia is characterized by loss of appetite, low levels of energy, desperation, excessive anger, social withdrawal and working long hours to compensate for declining performance, troubles in concentration, guilt and suicidal thoughts.
A 2005 study published in the Journal of the American Dental Association claims that 10 percent of the 560 dentists surveyed suffer from this condition. However, only 15 percent of them are followed by a doctor and receive treatment.
Dr. Lavigne has known depressive individuals who have committed suicide, and he feels reassured by the prevention program now in place. "To my knowledge, there hasn't been a fatal act at the Faculty of Dentistry in the past 10 years," he says. "The program seems to have had the intended preventive effect. And depression is less stigmatized today, contrarily to my generation, youngsters today speak about it more openly. This helps us provide them with better support."