To give a completely hypothetical example, if someone has an illness like schizophrenia and they are having an acute episode of psychosis and they are thinking of death or requesting suicide or requesting PAD, it's because of a hypothetical belief that if they don't die, then the whole planet is going to turn into dust. There is a delusional belief that's driving the suicidal ideation or the request in that case. This is where the capacity assessment is important, to differentiate whether or not that request is driven by delusion or by a distortion that's driven by the mental illness.
A similar scenario could happen with someone—and I will change this example for privacy—who has schizophrenia but then develops a treatable cancer and is refusing the treatment because they believe that if they get the treatment, their sibling will get the cancer. In this case, the decision to receive a treatment or to request PAD because of the cancer is driven by the delusion that if they don't die, then their sibling will get the cancer. I think this is where it's important to engage a psychiatrist to assess the capacity and to determine how much of the request for PAD is driven by delusional thinking. I hope this answers your question.