In order to answer this question, it is important that we first discuss what depression is. Feeling sad, lonely or low is very common. So how can we point out which is depression and which is sadness? Well, sadness is a fleeting feeling and is the most normal reaction to loss or life’s struggle. Depression, on the other hand, is pretty permanent (may be not permanent, but it may last really really long or may occur very frequently, if not consulted with a professional). It is so overwhelming and inexplicable that these mental feelings start involving physical symptoms as well. Depression can keep an individual from leading a normal and an active life.
Depression, if not treated, may take an even worse form and might possibly end at suicide. Clinically, certain symptoms that occur persistently might point towards depression.
Here comes the part about guilt and shame. One of the very common symptoms of depression is feeling of unnecessary guilt or shame. Guilt is a feeling of remorse or regret for violating an internal value. Shame is an overall feeling of self contempt. While both these are pretty normal feelings for a normal individual, for depressed individuals, these feelings get magnified to unimaginable extents.
How are these manifested?
The next plausible question is why does this happen?
These feelings generally tend to go back to childhood. People who have faced childhood traumas or have been physically, emotionally or sexually abused are more prone to feelings of depressive guilt or shame. In the young age, they do not really have proper understanding of the situation and hence they end up blaming themselves. During adulthood, they keep believing the same, thus causing intense feelings of guilt and shame. A lot of counselling can bring such individuals to the understanding that whatever happened to them as children was never their fault.
Also, it has been researched that the region in the human brain associated with shame and guilt is unusually active in depressed individuals. If you wish to discuss about any specific problem, you can consult a Psychologist.