On the metabunk.org  you will find another 2 articles that offer possible explanation that there was a propaganda campaign at this time by the Church of Scientology .  In theory (it) could be how the conspiracy was started. They had a magazine and their reports about this stuff was published.  I know of no source and would wrote about it. Perhaps there is one but this possibility is too far out there. The articles were based upon interpreting declassified receipts of a CIA MKULTRA Mind control deal rather than stuff they purely made up.  Even the craziest of conspiracy theories has grains of truth. That is why people fall into them.  They must be put into perspective.