From the article entitled: "Religion”
“Each religion asserts that it is a means by which its adherents may come into closer contact with God, Truth, and Spiritual Power. They all promise to free adherents from spiritual bondage, and bring them into spiritual freedom. It naturally follows that a religion which frees its adherents from deception, sin, and spiritual death will have significant mental health benefits. Abraham Maslow's research after World War II showed that Holocaust survivors tended to be those who held strong religious beliefs (not necessarily temple attendance, etc), suggesting it helped people cope in extreme circumstances.”
http://creationwiki.org/Religion
____
Also it is logical to conclude that the closer you are to
universal truth the happier or more fulfilled you will be over the long term. This is not to say there aren’t some happy (or at least temporarily happy) atheists out there, but it is possible that they could be even happier if they were closer to the truth (if atheism was not in reality true).
This could also apply to societies, if a society is in touch with universal laws and truth it would be logical to assume that that society as a whole will be better functioning and its citizens as a whole will have better mental health. If secularism is the closest to truth of all belief systems it would seem Europe should have a lower mental health problem.