William White, a DXM researcher, concluded that Olney's lesions were forming in humans, but retracted his statement in 2004.[11] In 2003, Cliff Anderson, a researcher and critic, wrote an article that illustrated that the tests conducted by Olney and Farber did not provide any conclusive evidence that lesions develop in human brains after exposure to dissociatives.[8] Anderson quoted Karl L. R. Jansen's book, Ketamine: Dreams and Realities, which cited unpublished studies on monkey brains. White's opinion that DXM caused Olney's Lesions therefore came under fire. From Ketamine: Dreams and Realities:[12]
Roland Auer injected monkeys with MK801 and was unable to produce any vacuoles.[...]
[R]ats have rates of brain metabolism that are almost twice as high as those in humans to start with. It is because of this higher base rate of metabolism that ketamine causes over-excitement in rats at doses below those at which it activates shutdown systems.
Frank Sharp also works in this area. I discussed with Sharp how this issue stood in 1998. His view was that reversible toxic changes in the rat started to appear at 40mg/kg and reached a level at which no further changes occurred (a plateau) at 100mg/kg, when a little cell death could be seen - but matters would not progress beyond this point. Extensive attempts to produce toxic changes in monkeys had been a total failure at doses up to 10mg/kg i.m. These monkey studies are unpublished. I sought the view of Olney's colleague, Nuri Farber. The work of his team indicated that N-P receptors must be blocked for at least 2 hours to cause reversible changes, and at least 24 hours to produce some cell death, in rats. [...][H]e thought that the methods used in monkey studies so far were unsatisfactory, because the animals were probably too young. Only adult rats show the toxic changes. He was not prepared to accept a clean bill of health for the drug in primates until this work with older monkeys had been done, and until the drug companies published their monkey studies to support their claims of harmlessness.
There is thus no published evidence at this time (January 2000) that ketamine can produce toxic cell changes in monkeys. The unpublished monkey data that we know about, that of Frank Sharp, actually shows that there is no damage at doses up to 10mg/kg.
White therefore concluded that based on some fundamental differences between rat biology and human biology and because there have only been very few studies done on the occurrence of Olney's lesions, no connection can currently be proved or disproved.[13]
