Gateway Drugs Theory

Gateway Theory

The temporal order observations gave rise to the "gateway theory" (also known as "gateway hypothesis" and "stage hypothesis"), which was predated by the similar "stepping-stone" theory that first appeared in the 1930s. The latter assumed that consumption of a "soft" drug, such as marijuana, inexorably sets an individual on a trajectory to addiction to hard drugs. The gateway hypothesis (GH) relaxes the inevitability assumption, but postulates a progressive and hierarchical sequence of "stages," whereby the use of a drug at a "lower" stage (a softer drug) is necessary for progression to a harder drug. This sequence applies only to the use of different drugs rather than different levels or extent of drug involvement (from use to dependence). Originally, as proposed by Denise Kandel in 1975, the "gateway" substances were considered to be beer or wine, which later was changed to marijuana.

Gateway Hypothesis Controversy

The few testable components of the GH include its premise that initiation of use of various drugs is not opportunistic but follows certain stages and pathways, and that the use of a drug at a lower stage is necessary for progression to a higher stage. The GH perspective has been presented as a theoretical antithesis to the concept of nonspecific problem behavior outcomes such as substance use disorders.

The "stages," however, are defined in a circular manner: A stage is said to be reached when a certain drug(s) is used, but that drug is supposed to be used only upon reaching that stage. In effect, the drug is identified with the stage. In other words, there is no process, separate from drug use per se, which is hypothesized to underlie the supposed developmental staging indicated by drug milestones. Moreover, the notion of "stage" itself is redefined from its common denotation, such that the later stages are assumed to be reachable before the earlier ones, apparently to accommodate the need in relating the GH to the conventional biological developmental framework. Any explicit causal proposition for the observed sequence is avoided. The numerous implicit statements of [Page 418]causation from the proponents of GH merely restate the observation of a sequential order. Indeed, it is hard to discern a falsifiable element in the GH beyond that observation, as is characteristic of inductive theories. The vagueness of a gateway drug itself is admitted by the originator of the GH. Virtually every proposition of the GH is qualified by a disclaimer, effectively engulfing and neutralizing possible arguments to the contrary. All possible deviations from the hypothesized "basic" sequence are automatically relegated to the category of error, or random, or nonsystematic patterns. Because the "stage," the main component of the gateway hypothesis, is defined by the drugs used at this stage, it is not surprising that the "stage" sequence parallels ranking of the prevalences of use of respective drugs.

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