It has to do with attitudes towards and understanding of disease. In China, if you ask if people are depressed, almost no one says yes. If you ask a slightly different question (I don’t remember the term the Chinese Professor I was talking to used), you get the same rates of depression there that you get in the US.
It is very difficult, therefore, to get accurate representations of rates of mental illness. In different cultures, there is more stigma attached to it, so fewer people are willing to report it. Some countries don’t even take statistics. One study, reported in the New York Times found the following:
_Chart: ’‘A Worldwide Problem’’ From 2001 to 2003, World Health Organization surveys measured the prevalence of serious mental disorders in the populations of various countries. DEVELOPED COUNTRIES United States: 7.7% France: 2.7 Belgium: 2.4 Netherlands: 2.3 Japan: 1.5 Germany: 1.2 Italy: 1.0 Spain: 1.0 LESS DEVELOPED COUNTRIES* Colombia: 5.2% Ukraine: 4.8 Lebanon: 4.6 Mexico: 3.7 China Shanghai: 1.1 Beijing: 0.9 Nigeria: 0.4 *As classified by the World Bank (Source by Journal of the American Medical Association).
The question is not so much why Americans suffer from depression, as why people suffer from depression. There is no accurate way to find out if depression rates are any different in other countries.
Depression has many causes: genes combined with environmental triggers is the short reason. Countries with more stressors have higher rates of depression. In the US, there is the pressure to succeed by amassing wealth that is not felt as strongly in other countries. Countries with wars have higher rates of depression. Anyway, there are a lot of theories, but as far as I can tell, not a lot of data.