Marijuana An ongoing research project headed by associate professor of psychiatry Harrison Pope had one subject who had smoked marijuana every day for a long time. To participate in the research-which actually concerned not drug use but testosterone-he had to stop his marijuana use. The man had been such a heavy use that, even four weeks after quitting, detectable cannabis residue appeared in his urine. But one day soon thereafter he told Pope that he "woke up and felt alert for the first time in years. The acute effects of marijuana, whose botanical name is cannabis, are well documented, but scientists know far less about the residual, or long-term r