When Bob Dylan sang that "everybody must get stoned," he was more correct than he knew. It turns out that our brains contain a natural chemical, anandamide, that attaches to the same brain sites as THC, the active ingredient in marijuana. Apparently, all of us are literally pot-heads.
While this revelation raises all sorts of important questions---for example, does Bill Clinton's brain inhale?--there's also a downside. Psychologists at Queen's University in Ontario report that anandamide, like THC, interferes with memory. Exactly what such a chemical is doing in the brain in the first place remains a mystery. But researchers hope the answer will shed some light on the origins of memory disorders like Alzheimer's.