Olney's Lesions and Dissociative Use

Olney's lesions are one of the primary arguments against recreational use of dissociative anesthetics. First described in 1989 in tests conducted by John W. Olney, these lesions showed correlation between dissociative use and brain damage in rodents. However, how much of a risk to the casual dissociative user do Olney's lesions produce? Has Olney's conclusions become outdated over the course of the past eighteen years, or does the danger still hold its validity enough for dire warnings against dissociative use to continue?

Olney conducted his study in 1989 using an experimental dissociative drug called MK-801 (Dizocilpine). Olney was actually testing the drug to see if it had potential in preventing brain damage from strokes, but ended up discovering that the dissociative was causing brain damage in the experimental rats. What he noticed were small holes or vacuoles that had formed in regions of the cortex due to the high doses of the drug. These holes constituted permanent brain damage in the rodents.

What's wrong with Olney's study? Well, for starters it should not be taken as bible truth that people who use ketamine, dextromethorphan (DXM), or phencyclidine (PCP) will develop Olney's lesions with use of these drugs. Olney was not conducting his experiment to see if MK-801 would cause lesions on the cortex, and was thus not using incremental doses to see at what dosage level or frequency of dissociative use was needed to produce these results. In addition, very small numbers of people if any use MK-801 as a recreational psychoactive substance. Olney did not research ketamine, DXM, or PCP (the three most commonly-used dissociatives by far) in his study and therefore only theoretical stances can be taken concerning MK-801's effects on the brain as compared to these substances. Furthermore, rat brains operate at a metabolic rate nearly twice that of humans. According to a data survey published by Cliff Anderson in 2003, the appearance of lesions in Olney's experiment required the test rats to be subjected to NMDA channel block (the characteristic action of dissociatives) for at least 24 hours in order for the cortex damage to manifest itself.

The biggest problem with research concerning Olney's lesions is that there have been absolutely no correlative studies conducted with human subjects who have a history of dissociative use. In such a study, both experimental data on test animals and data on the brain chemistry of dissociative users would need to be compared and contrasted. In addition, research into all three categories of commonly-used dissociatives would need to be done, since DXM is stronger than ketamine and PCP is stronger than DXM. Unfortunately, no such study has yet been undertaken. In the meantime the media and U.S. government have continued to propagate the idea that use of dissociatives carries with it the very real risk of Olney's lesions and permanent brain damage. Even if the risk for the lesions in humans is real at high doses or as a result of chronic use, there is no experimental evidence to back up that claim as even remotely official.