What are the bad effects of using marijuana ? such as nurological and physical ?

THC and Psychosis: If you have a personal or family history of psychosis then smoking thc is contraindicated. Thc can cause social anxiety and certainly it can worsen it as well. Thc causes a fixation of the personality at the age that you were at when you started using it. This explains the often adolescent like behavior of adults who indulge frequently in thc. It can also impair your ability to think rationally. I have seen several extreme cases of depersonalization from smoking up to 15 joints a day for 13 years. This occurred in two best friends.