Jewish Perspectives on Physical and Mental Health
The famous question that has been asked for centuries is how can we heal a patient? G-d decreed that they should become ill, so what gives a physician the right to heal? The Gemara addresses this question (Bava Kamma 85a, Berachos 60a) by saying the fact that a double lashon is used, vrapo yirapai (Shemos, 21:19) teaches us that man has permission to heal. This shows us that one has permission to heal, but that it is far from an obligation. The gemara asks ‘from where do we know you must treat someone who is sick?’, and it answers that there are actually 2 sources:
One is learned from returning lost objects, which includes returning someone's lost health. The second is from the pasuk lo samod al dam rayecha - do not stand idly by the blood of your neighbor (Vayikra 19:16). The gemara states that we need both sources to teach us that even when you cannot physically help the sick person you would need to hire someone that can.
When we hear hearing the phrase ‘restoring one's health’, we likely picture someone afflicted with a serious infection or serious physical disease. Notably, mental health is included in this pasuk. There are numerous sources in the Gemara that point to the legitimacy of the need to address mental health (see Care of The Critically Ill, Quality and Sanctity of Life). Some reference the story of Chuni Hamagol (Ibid). He was a tremendous talmud chacham and he fell asleep for 70 years. Upon awakening, people did not believe he was that great sage from 70 years prior. This caused him great distress. So much so, that he prayed for death and G-d acquiesced. One may have thought that mental health is inconsequential. How could this great tzaddik pray for death, and furthermore, how could G-d have granted it? We see from this chain of events that emotional pain and suffering is quite significant.
It is also well known that “mental” health greatly affects "physical" health. There are many Torah sources that speak about this. The Shulchan Aruch (Yoreh Deah Siman 337) paskens that if a close relative of a sick patient dies, the patient should not be informed so as not to cause him heartache [and make him sicker].
Furthermore, a physician should not inform a patient of a diagnosis of terminal illness if it will cause the patient undo distress and thus worsen their condition (YD 337). This can be complicated to implement because according to American law, a patient has the right to know what any diagnostic test reveals. A good solution may be to first ask the patient if he wants to know the results of the test. If the patient wants to know, it's important to ensure that your words are chosen thoughtfully to avoid conveying a pessimistic tone.
This ties into the idea that one should never give up hope. This is illustrated by the following story. We know that Shmuel the amora was a physician. He was once sitting with a gentile named Avleit and they saw a man walk into a swamp to cut reeds. Avleit remarked that he saw in the stars that this man will be bitten by a snake and die. Shmuel responded that if the person is a Jew he will be unharmed. The man returned from the swamp with his bag of reeds and Avneit looked inside the bag and saw a snake cloved in two. It turned out that this person had given charity that day. Shmuel exclaimed “charity saves from death” a verse found in mishlei (10:2) (shabbos 156b).
With the above story we see that even if someone has a poor prognosis and even if written in the stars it says he will die we should not give up hope. Ein mazal b'yisroel - There is no destiny [or luck] in Klal Yisrael. Even for a gentile we should not give up hope because we are not G-d and only He knows what's going on with the patient. Reb Yonasson Eibshitz even goes on to say that we should not treat any internal illness because we don't know for sure what is going on in the body. It seems that we do not follow this psak, but we can still learn from it that we should not give up hope because only G-d knows what is truly going on. One should be realistic but always hopeful.