Dated 14 July 1954, this document outlines CIA
experiments in tolerance to LSD at the Addiction Research Center in
"Our experiments on tolerance to LSD-25 have been proceeding well, although I continue to be somewhat surprised by the results, which to me are the most amazing demonstration of drug tolerance I have ever seen. I have seven patients who have now been taking the drug for more than forty two days. One of these patients receives 1 mcgm./kg. daily, four receive 1.5 mcgm/kg. daily, and two receive 2 mcgm/kg. daily. All seven are quite tolerant to both the physiological and mental effects of the drug. We have attempted to break through this tolerance by administering double, triple and quadruple doses..."