I think that any drug/substance that changes your mode of thinking has the potential to create mental health problems. I also think those mental problems were latent or even fully present when the user chooses to try a new chemical/drug. Trying to fill a void or fix a mental issue using chemicals doesn't usually work out too well, and I think it exacerbates the problems. You might get a little "mental vacation" from your problems, but when you sober up, those issues are often worse because you decided to ignore them. This is what leads to addiction, chasing the ability to cover up your issues by making yourself dead inside, or changing your mode of thinking to ignore what is really going on deep down.

I'm a believer that psychedelics, including Marijuana, can be helpful. It really depends on the circumstances of why you are using the chemical, and what your intentions are going into the experience.