Depression as an Illness

I am a mental health therapist. I have a client (patient) whose condition is as follows: He is completely in touch with reality, with no risk of psychosis. However, he is a very emotionally sensitive individual and also had a difficult childhood. As a result, sometimes things that are considered 'trivial' to ordinary people can cause him great stress or a depressive state. For example, fasting makes him extremely anxious and depressed. He feels completely ‘out of whack’ mentally because of it. Can it be said that he has the status of a sick person whose life is not in danger in Jewish law?

Greetings,
Mental health issues, such as anxiety and depression, are considered physical illnesses in every respect. They are certainly considered as non-life-threatening illnesses in all aspects of Jewish law. [For example, regarding taking medication on Shabbat, being exempt from fasting, and the like.]
Sometimes, when there is a risk of mental deterioration, it is considered 'a situation that might be life-threatening’, and then he has a status of a patient whose life is in danger.

Shulchan Aruch, section Orach Chaim, chapter 326; ibid., chapter 550.