An unintentionally humorous passage from Kurt Schneider's Clinical Psychopathology has it that 'complaints of cyclothymic depressives or schizophrenics that they are no longer alive should not be taken literally.' (p. 121).
The passage - less amusingly - continues: 'The very statement presupposes an experience of existence, dulled though this may be. Sometimes there is actual (nihilistic) delusion present. Distressing changes in bodily sensation or hallucinations may give rise to these utterances.'
Could someone literally believe that she had died? Does, say, the Cotard delusion sufferer literally believe that she has died? ... Surely anyone who answers either 'yes' or 'no' to such a question has quite a bit still to learn about severe psychopathology. (I'm not suggesting that Schneider would answer 'yes' or 'no'! He knew more than I about psychopathology...)
Does the schizophrenic intend her own words metaphorically? The new question is surely no better. When what we have to do with is delusion then we're dealing precisely with such thought as can no longer carry descriptions of it as either metaphorical or literal. (We must learn to hold our peace. To not do so is to insist that the mad be sane, and that is to fail to meet them where they're at.)
What for that matter would it mean to 'believe that one is alive'? At best, perhaps, that one knows how to use the word 'alive'?
To the extent that Schneider's passage means anything, I propose that he's wrong. He's wrong if he thinks that we may safely infer from this patient having a 'dulled experience of existence' to her meaning her 'I'm dead' complaint metaphorically.
'Perhaps the patient thinks he's died and is now in the afterlife?' Oh please! Enough already! Learn this: madness breaks the mind and, therefore, along with it, the language which expresses this mind's broken thought. But this provides no occasion for us to take empathic leave of the patient. It's in his broken language that we encounter him in his brokenness.
Encountering the schizophrenic with understanding requires of us that we be heartbroken at what we find.