Marijuana makes it harder to breathe, easier to go psychotic

WELLINGTON, New Zealand (AP) — A single joint of marijuana obstructs the flow of air as much as smoking up to five tobacco cigarettes, but long-term pot use does not increase the risk of developing emphysema, new research suggests.
The study by New Zealand’s Medical Research Institute found that longtime pot smokers can develop symptoms of asthma and bronchitis, along with obstruction of the large airways and excessive lung inflation. The paper was released yesterday ahead of its publication in the journal Thorax. Last week, another study published in The Lancet medical journal suggested that using marijuana may increase the likelihood of becoming psychotic, with even infrequent use potentially raising the risk by up to 40 percent.