How does narcissism relate to depression?

A good question: Basically narcissism tends to isolate the person from others because it's all about them. It tends to wear out family and what friends they have. Isolation can lead to anger and loneliness, a sense that everyone around is against them and being unfair. It's a very short step then into depression. Hopefully someone will have the kindness and courage to encourage them to get help.

Narcissism: In some people, narcissism may be a state used unconsciously in order to cover depression. There is some theoretical evidence to suggestion that emotional deprivation in childhood may be one causative factor.

Narcissism: Personality disorders in general are at higher risk for suicide. Narcissists eventually drive everyone around themselves away through the toxicity of their very presence. and cannot see or understand their part in their own misery, which leads eventually to depression and possibly suicide. The core of it is they cannot face their own abysmal self-esteem or the reasons for it.