Where Does Depression Come From Anyway?

People can feel depressed following major life stresses such as the death of a loved one, a break up, or losing a job. But what happens when nothing is wrong? Why do some people get depressed when things are humming along just fine?  Depression’s cause is thought to be a result of a decrease in neurotransmitter levels, and this can occur in the absence of a life stress also. Watch the following video at About.com to get a better understanding of the biological basis for depression.