This in turn affected scientific thought and it came to be generally assumed that these substances could never be taken on a long-term, regular basis without causing serious harm. It was also believed that these substances were almost always used by people with profound personality disorders. Studies of drug consumption tended to equate any type of drug use with abuse and seldom took occasional or moderate use into account as a viable pattern. It was only after the mid-seventies that an approach similar to the one used for alcohol research , comparing different patterns of consumption, came to be applied to illicit drug use leading the scientific community to recognise the importance of the wide range of using patterns. The first has low social costs while the second is dysfunctional and intense and its social costs are high.
Rituals embody the precautions to be taken before and during use.
Here the observance of traditional taboos and rituals seem to provide paradigmatic examples of Zinberg's and Grund's theories of controlled drug use. One of the most widespread of these entheogens is ayahuasca. This is a psychoactive brew made from the Bannisteriopsis caapi vine and the Psychotria viridis leaf which has been used for many purposes by the native inhabitants of Western Amazonia since time immemorial. Its psychoactive properties are given by alkaloids such as harmine, d-leptaflorine , DMT and harmaline, which appear in varying concentrations . Conceived of as a means of opening the human perception of the spiritual world, this brew has been used mainly by shamans for a series of purposes such as the diagnosis and treatment of a large variety of ailments, divination, hunting, warfare, and even as an aphrodisiac.