[bgsavings]

As Zeddoo pointed out, there are underlying conditions that have been recorded as being triggered by MJ and, I would expect, other 'recreational' drugs.
There may have been a mental condition that wasn't affected by any drug use, but it would be unlikely to help.

I've known (at least) two people who were affected by LSD to the point of being put into hospital, one recovered and the other commited suicide (stole mother's car and smashed into a bridge abutment) when on a home release. Both were apparently fine beforehand.
Datura is another 'natural' plant that has had those trying it doing some very strange things, like self mutilation.