I was always told that marijuana could increase already present mental problems in certain people. Not everyone reacts the same to marijuana.
If a person is paranoid, pot can increase that proclivity.
Don’t really know how true that is. But if it is, I would not be surprised because many mind altering drugs can have that effect.
Reminds me of a bit from Bill Cosby about Cocaine. Someone told him that it enhances your personality. He replied "Okay what if your an A$$hole?"
Yep, the one time I tried it is college I flipped out. Never tried another drug. I mentioned this on a previous thread on FR and was called all kind of liar (years back). Everyday more evidence shows that those that say "it is a safe mellow drug" are lying through their teeth.
It depends on the person. Pot is a mind altering drug and God made our minds so complex that finding a drug that works perfectly on everyone is near impossible.