There is no blood test for depression, no x-ray nor sonagram. Depression is the label that is given to a constellation of symptoms. There are theories about the cause of the symptoms. But the diagnosis is more like tea leaves.
Depression Diagnostic Criteria
· Lasting sad, anxious, or empty mood
· Loss of interest or pleasure in activities once enjoyed, including sex
· Feelings of hopelessness or pessimism
· Feelings of guilt, worthlessness, or helplessness
· Decreased energy, a feeling of fatigue or of being “slowed down”
· Difficulty concentrating, remembering, making decisions
· Restlessness or irritability
· Sleeping too much, or can’t sleep
· Change in appetite and/or unintended weight loss or gain
· Chronic pain or other persistent bodily symptoms without physical cause
· Thoughts of death or suicide, or suicide attempts.
If you have five of the above, including one of the first two, for more than two weeks, and without appropriate reason (like, your mother died) then that's depression. You've got the Grim at the bottom of your teacup.
I have done enough intake interviews that I recognize the differential diagnostic tree when it's coming at me. I used to get nervous when they asked about guilt. No, I don't actually feel guilt, except appropriate guilt for recent misbehavior, not the horrible self-judgment for imagined offenses. I don't feel guilty for my depression. I am not the offender but the offended.
No, what I feel about my depression, and events that are related, is shame. And what I really feel shame about is feeling shame.