Western Medicine has come a tremendous way and can now heal cancers, previously deadly diseases, and many other health problems. Western medicine has become so prevalent that it has pushed out a number of previously effective healing practices that are much simpler, cost effective, easier and more pleasant to apply. Additionally, sound and long-term focus of health is great for disease prevention.
I am not aware of particular studies done on healing by mental attitudes, but I have personally seen a number of people being helped from changing their attitudes to be more positive, and have a reverse health effect when their mental attitude becomes more negative or hopeless.
Personally, after working on a company that was struggling, I went through a lot of stress and began to experience back pain that kept getting worse as the amount of my stress was increasing. Once the company began recovering, I became happier and my stress became “good stress” as I was happy to work hard. Surprisingly, my back pain began to be better. I also noticed myself having more energy for daily activities.
A negative mental attitude can kill just as much as positive attitude can have a healing effect. A nurse once told me that she refrains telling patients who are terminally ill that this is the case. Instead, she focuses on helping people fight and see positive things that can attempt or look forward to. The nurse told me that she has been doing that after earlier on her career she was more straight forward with her patients and a number of them lost hope, stopped fighting, and did not make it. Once the nurse started being more encouraging, she reported seeing a higher survival rate among her patients. She then started to put more emphasis on mental attitude positivity, and giving her patients hope and a feeling of being needed. She told me that this rejected in overall increased patient well-being.
Ultimately, Western science deals with things that are quantifiable and measurable. Mental attitude is difficult to measure and science has not focused on the effect of attitudes on health. It is too bad because many people can focus on their attitudes and mental positivity which help them improve their health.