Up to now researchers were confident in saying that a particular type of gene was the cause of depression. Now new research has shown that this may not be so. The project called Human Genome which is mapping the entire DNA is not been able to identify a single gene that is connected with any mental illness, including schizophrenia.

Research has found that depression seems to be more common in developed nations and especially among women belonging to low income groups. Geographically the least affected by depression are the countries in the Far East. Researchers have narrowed down certain critical factors that can make a person more prone to depression. The first is maltreatment during childhood, particularly during the first year if the parents were unresponsive. The younger the child maltreated the higher is the risk of the person growing up depressive. Secondly it has been found by conducting a proper study that mainly nations who are English-speaking are much more likely to get various mental illnesses compared to Europe. The United States was found to be the worst hit, where almost 26% of the people are having a depressive condition once a year.