Okay, I see a lot of people blaming a lot of things on weed + addictive personality/underlying mental problems. My question is this: is weed the ONLY drug you put into your body? Do you drink, use caffeine or tobacco or other illegal drugs? Alcohol destroys liver and brain cells, as well as aggravating ulcers, IBS, and other bowel problems, so if you drink, consider this as the cause. There is no scientific evidence that marijuana causes ANY type of intestinal damage. That's not to say it's not real, but when you look at unbiased scientific and medical evidence, you'll see that marijuana is among the safest substances in the world. Safer than aspirin, caffeine, alcohol, and cigarettes, and fatty foods, and...you see where this is going. If it was really so bad for the immune system, lungs, brain, and personality, why are states increasingly decriminalizing medical mj for patients in the illest of conditions based on scientific studies proving its benefits in treating everything from glaucoma to AIDS wasting syndrome to anxiety to cancer treatment side effects?
On the flip side, there is some evidence suggesting that cannabis brought out or worsened schizophrenia in a couple of people with a genetic predisposition to the disorder. There's no account of it causing cancer of any type, even in long-term (30+ years) heavy smokers (5+ joints a day), so that can also be "thrown out the window." As with ANY activity, smoking weed in excess is not wise: it can irritate airways, cause short-term memory impairment (while high mostly), as well as being expensive and putting a person at risk for arrest, as it's illegal. The problems with weed usually come from overuse, use in the wrong setting, and increased doses in people with mental problems.
Moderation is the key to everything! I hope everyone who's experienced negative effects from this wonderful plant recovers fully! Bless.