The withdrawal alone is evidence that it's doing something negative to your brain. I hear potsmokers say that alcohol is so much worse. That really depends, doesn't it? I know longtime pot smokers who have psychological issues as well as physical, from the weed. Let's not forget that weed grown today is something like 100x stronger than it was in the 60s. It's a drug like any other. Cocaine comes from a plant and it destroys your heart. The natural claim is bunk, as many, many natural things are detrimental to human health. Anyway, all I am going to say is there are longterm pot smokers in my immediate family and none of them are in good shape mentally whereas once they were quite shapr and creative. It kills something in you. Brain cells, it would seem.