It is common to experience depressed moods or "the blues" at some points in life. Most often, these periods of sadness occur as a result of a life change. These changes may be in the form of a personal setback or a loss, such as the death of a loved one. The painful feelings that accompany these periods are usually temporary and should be viewed as normal parts of living.

However, when feelings persist and result in significant distress or dysfunction in daily activities, then the depression should be considered a medical illness that requires treatment. Severity and duration of symptoms are the key factors that distinguish normal sadness from a clinically significant diagnosis of depression.

The causes of depression are not clear. Several factors appear to work together to cause a depressive illness. A key underlying mechanism may be linked to abnormalities of the brain's messenger systems. The brain levels of the chemical messengers serotonin, norepinephrine, and dopamine are decreased in depression, which is thought to contribute to clinical symptoms.

It would appear that stressful and traumatic events can also trigger depression in some individuals. A family history of depression or genetic factors can play a significant role. Other risk factors include female gender and experiencing the loss of a parent in one's childhood. Therefore, most clinicians agree that depression is caused by a complex combination of biological, psychological, environmental, and social factors unique to each individual.

Clinical depression is an illness that can afflict anyone, regardless of age, race, class, or gender. About 10 to 25% of women and 5 to 12% of men can be expected to suffer from a significant depressive illness at some point during their lives. Treatment is always indicated. In some cases, the severity of symptoms may be serious enough to warrant hospitalization in order to provide appropriate care or protection from self-harm.

Unfortunately, there remains a 15% risk of death from suicide among individuals who have the more severe forms of depression. Despite these alarming statistics, over 80% of Canadians with depression do not receive treatment for their potentially life-threatening illness because they don't believe they need it.

Are you clinically depressed? Our "9 symptoms of depression" tool can help determine if you need professional help.