Do the rates of depression vary among different ethnic groups?
Different ethnic and racial groups may have different genetic susceptibilities to depression. We don't know this yet, but it's certainly conceivable.
There are some consistent findings. For example, the rates of depression are consistently lower in Mainland China and Taiwan. The Chinese have the lowest rate. The Japanese are next, and Koreans have the higher rate, but still lower than any of the European countries or the Americas.
Now, we don't know whether that is a result of the cultural expression of the disorder, although these studies were done in these communities by people in the community.
James Jackson, who is a very distinguished African-American scientist, has just completed a national study in the US showing that African-Americans have slightly lower rates of depression than white Americans. I think Jackson believes that the lower rate of depression is due to the fact that African-Americans have such difficult lives that they don't develop depression, but they do develop serious chronic illnesses like diabetes and hypertension.
These chronic illnesses many be due to life stress or they may be due to engaging in risky behaviors due to life stress such as smoking, over eating etc.