I'm not talking about mental disorders, but about personality issues and general levels of happiness. People with intellectual personalities often make things harder for themselves, which is the point of the curiosity-kills-the-cat story. See the links below.
I wouldn't appeal to psychiatry in defense of religion, if I were you, because beliefs in the supernatural qualify as delusions for any psychiatrist worth his salt. Thus, religious people technically suffer from mental disorders (except that psychiatry defines mental disorder as deviance from a society). Those disorders or flagrant delusions happen to make religious people happier, but only in the sense that someone stuck in the Matrix is bound to be happier than someone who's awakened to the harsh, unflattering reality.
The point is that the human brain may have evolved to delude itself, not to discover and to be comfortable living with cosmic, scientific truths about nature's inhumanity.
This is commonsense stuff.
https://www.theladders.com/career-advice/why-smart-people-fail-to-be-happy
https://www.inc.com/geoffrey-james/why-are-smart-people-so-miserable.html
