The Thirty-Year Gap

Between the mid-1950s and the mid-1960s, a substantial body of clinical research was published on psychedelic compounds, principally LSD and psilocybin. The volume ran to hundreds of papers and thousands of subjects. The quality was uneven by modern standards, with small samples, weak controls and enthusiastic investigators, but it was a live research field with funding and institutional homes.

By the early 1970s it had almost entirely stopped. In the United States the Controlled Substances Act of 1970 placed these compounds in Schedule I, defined as having high abuse potential and no accepted medical use. International scheduling followed under the 1971 Convention on Psychotropic Substances.

The consequence was not a ban on research. Schedule I permits research under licence. The consequence was that obtaining the licence, a supply of legally manufactured compound, a registered secure facility and institutional ethics approval became difficult enough, and reputationally costly enough, that almost nobody attempted it for a generation.

That is a specific and unusually clean mechanism. The question was not settled by evidence. It was removed from the set of questions a working scientist could practically ask, by an administrative classification that itself asserted the answer: no accepted medical use.

The circularity is worth stating plainly, because it is the whole architecture. A compound is scheduled on the grounds that it has no accepted medical use. The scheduling makes research into medical use impractical. The absence of research maintains the absence of accepted medical use.

The resumption is recent and is the reason this can now be assessed. Work restarted at Johns Hopkins, NYU, Imperial College London and elsewhere from around 2000. Results in the treatment of depression, end-of-life anxiety and addiction have been sufficiently promising that the FDA granted breakthrough therapy designation to psilocybin for treatment-resistant depression in 2018 and to MDMA for post-traumatic stress disorder in 2017.

Careful reading of the current wave is warranted and the field itself has been saying so. Blinding is close to impossible when the intervention is unmistakable. Expectancy effects are large. Several trials have been small. Enthusiasm among investigators is a known risk, and it was a known risk in the 1960s too.

None of that is the point at issue. The point is that the questions being asked now are largely the questions that were being asked in 1965, and the intervening thirty years produced almost no data on either side.

That gap is the cleanest modern instance of the Index mechanism in this archive. Nothing was burned. No finding was refuted. A classification made a line of enquiry administratively impractical, and the field simply went elsewhere.

The scheduling remains in place in most jurisdictions while the trials proceed under exemption, which means the classification asserting no accepted medical use is currently coexisting with breakthrough therapy designations. Both statements are official.