This may be the reason the "Me" generation in the United States has the highest rates of depression ever seen. This makes perfect sense. Humans are very social creatures and I think we tend to forget that in the West. We live in a culture which emphasizes the self; self esteem, self fulfilment, self care, self awareness. Living in a culture which focuses more on how well you interact with others and your place in and contribution to a group allows people to feel more connected and valued. Being part of a group also provides an individual with a vast support system which inhibits the isolation and withdrawal present in depression. Finally, the emphasis of the West on individual success, which is usually measured in how much money you make or things you possess, is becoming harder and harder to achieve, creating more and more people who are "unsuccessful". Feeling unsuccessful leads to depression. If success is measured instead by your contributions to and participation in a group, you are more likely to be able to succeed and feel valued by the community in which you function. This would eliminate a source of depression.
'Culture Of We' Buffers Genetic Tendency To Depression, Science Daily, October 30, 2009.