Finally I have gotten around to reading the recent study published in the British Journal of Psychiatry titled "Religion, spirituality and mental health: results from a national study of English households". This paper is pretty old, but I only recently learned about it.
The big finding in this manuscript was that the so called "spiritual" respondents had a greater chance of suffering from mental illness than atheists (non spiritual and religious respondents) and theists (religious respondents). This is not surprising as religious people have some kind of life framework. In the same vein, atheists are generally more rational and as such would also have a life framework. In contrast spiritual people are more open to different concepts and this can, in my opinion, be related to a more susceptible mind as your lifes framework is more flexible.
What I also found interesting that atheists have more fun than religious believers, no surprise there I suppose. Granted, this was in alcohol use and recreational (marijuana) drug use. However, besides these traits theists and atheists have the same probability of developing a mental health issue. So there are two ways to interpret this, and either way does not bode well for theists and their rules.
Option a: Marijuana and alchol are not bad for your mental health, as people that take them (or not) are equally as likely to get mentally ill. This conclusion is unlikely, as spiritual people who use drugs/alchol to the same level as atheists suffer a greater chance of mental health problems. For this reason I think it is safe to say that drugs can affect mental health.
This then leads us to option two and a very interesting conclusion.
Option b: Religion is as bad for you as recreational drugs and alcohol. After all, it has the same statistical effect on your mental health.
Just a thought. Enjoy the rest of your day.