The finger of blame pointed to increasing potency of black market material. In contrast to the cannabis of 1936, modern cannabis typically contains much more of the plant’s psychoactive compound tetrahydrocannabinol, but it also has reduced levels of a nonpsychoactive, anti-psychotic ingredient, cannabidiol. The latter is now showing therapeutic potential for the treatment of several serious illnesses. CBD, purified from specially bred cannabis plants, is entering clinical trials as a potential treatment for schizophrenia.