I find it fascinating how many medical "problems" we (Western medicine) have that are perceived differently by other cultures and faiths. I do believe what you say. Presumably Lithium deficiency is something which does not serve ones ability to contribute to our modern economy as much and therefore is seen as being a negative.
The reason is that those other cultures seem to have lots less of these illnesses. For schizophrenia, I can give some explanations. I believe that it's less common around the equator. Some link that to vitamin D levels, which are way too low in Europe and the US, even if you live in Florida. There may be other reasons, but it's worth noting.
Another big problem is stress, caused by competitiveness in the western world. When you have a mental illness, you can't compete, and that alone is another stress factor. (Some people will perform better, but by far the most will not.) In a low stress low competitive environment, if you can't deliver, don't have a high performance job, it's not that bad. You're one of the many, just one with a few quirks. You hear voices, so what. I guess if it's not that strange to hear voices, you don't have to hide it, and stress goes down, resulting in less voices, etc.
