my older brother is destroyed because of smoking marijuana all the time throughout his teens and most of his 20s-30s he has massive skitsofrenia ( bad spelling soz ) and it has ruined him, he has lost his child and cannot hold a job. he turned into my worst nightmare and i cant have contact with him now. marijuana can have very bad effects, it has been proven and shown from alot of people who have developed mental disorders but only if smoked throughout every day for every month for a lot of years.