Perhaps the denial results from a public attitude that depression itself is too depressing to think about.
Depression comes in many forms.
Some people are born predisposed to it, while others become seriously depressed only after some severe stress or emotional shock. Manic-depressives go through dramatic mood swings, from elation to hopelessness. Persons with depression may not feel sad, but simply empty. Depression is alarmingly widespread in the general Canadian population. BC teachers with 6 to 20 years' experience would fall in that age range.