PCP: The Killer Drug

The Man who Mistook his Wife for a Hat is a collection of case studies by Oliver Sacks in which he describes peculiar neurological cases based on his experiences with them. One particular case study features a man, whom Sacks refers to as “Donald”, who murdered his girlfriend while under the influence of PCP, a drug that induces violent and aggressive behavior that may also cause blackouts leading to no memory of what took place while under the influence. In this case, Donald maintained no memory of the murder and further, no conscious motivation to commit such a heinous act. PCP often causes extremely disorienting and realistic hallucinations in addition to inducing feelings of aggression and rage. This potent combination, in extreme cases, can lead to unbelievable cases of homicide. But this event wasn’t the last tribulation that dear old Donald would face. Years later, after being hospitalized for mental illness, he was struck by a car while riding his bicycle. This accident resulted in severe frontal lobe deficits and temporal lobe epilepsy. Temporal lobe seizures often cause hallucinations, which was the case for Donald, who specifically had experiential hallucinations. These hallucinations depicted intense visual imagery and memory of all details of the murder he had committed that had previously been repressed. This unfortunate event seems implausible if not impossible. Sacks suggests that this sudden remembrance may have been caused by a loss in frontal lobe function which would have reversed the repression that he had previously been experiencing. However, PCP, the drug that Donald was under the influence of when he committed the homicide, causes blackouts, meaning he should have never formed these memories that were suddenly intruding on his consciousness.

Similar cases of violence have been reported in the media, as they are often unbelievable stories including attempted suicides and homicides. For example, Andre Johnson, a rapper from West Hollywood, reportedly cut off his own penis and testicles before jumping out of a four-story building while high on PCP. More horrifying stories of homicides exist as well. In 2012, Chevonne Thomas decapitated her two-year-old son then put his head in the freezer. Thomas had smoked PCP-laced marijuana previously. She committed suicide shortly after calling 911 to report herself. Another gruesome case of a PCP blackout is that of Antron Singleton. He was charged with the murder of a 21-year-old L.A. woman. Authorities report that the woman was found with teeth marks on her face and on pieces of her lung, which had been removed from her chest. Additionally, a medical examination of Singleton found blood and flesh in his stomach that were not his own. PCP can be a life-shattering drug as evidenced by these horrific cases of murder and cannibalism. But what is this drug doing to the brains of its users that causes them to commit such heinous acts of violence?

Originally developed as a potent surgical anesthetic, phencyclidine was pulled from this use because patients were experiencing hallucinations and delusions following surgery. Because of the relative ease it takes to manufacture, he drug is illicitly used and abused. Interestingly, abusers of PCP experience psychosis similar to schizophrenia patients, causing many neuroscientists to take interest. These symptoms include hallucinations, delusions, paranoia, and disorientation. PCP acts as an NMDA antagonist in the brain.

An NMDA receptor antagonist inhibits the NMDA receptor by binding to the receptor and therefore blocking glutamate, a neurotransmitter, from binding to it. In the case of PCP, glutamate is unable to bind to its receptor and therefore deactivating it. Because of this, electrical signals that are typically used for communication between neurons and the spinal cord are blocked, resulting in a dissociative feeling. The nicotinic acetylcholine receptor is also inhibited by PCP. Schizophrenic patients show reduced CNS nicotinic receptor activity, suggesting a correlation between this receptor activity and the psychotogenic properties of PCP.

The NMDA system also has ties to learning and memory in the brain. Studies have shown that chronic and acute administration of drugs with similar mechanisms to PCP result in impaired performance in memory tasks. Case studies of individuals who have taken PCP show partial or complete memory loss while under the influence of he drug. Salient examples of this are the stories of murder or other crimes when the individual experiences a “black out” and retains no memory of the incident.

PCP induces vivid hallucinations and psychotic like symptoms. Coupled with the aggressive nature of people on this drug and its likelihood of producing blackouts, it is not unbelievable that people commit violent, uncharacteristic acts of violence and crimes while under its influence.

 

References:

Gorman, R. (2012, August 22). Camden, New Jersey, woman decapitates her 2-year-old son, then stabs herself to death when police arrive. New York Daily News. Retrieved from http://www.nydailynews.com/news/national/camden-new-jersey-woman-decapitates-2-year-old-son-stabs-death-police-arrive-article-1.1142042.

Kelleher, J.S. (2002, May 30). Aspiring Texas rapper to stand trial in death of L.A. woman. The Los Angeles Times. Retrieved from http://articles.latimes.com/2002/may/30/local/me-teeth30.

Morris, B.J., Cochran, S.M., & Pratt, J.A. (2005). PCP: from pharmacology to modelling schizophrenia. Current opinion in pharmacology, 5, 101-106.

Rezvani, A.H. (2006). Involvement of the NMDA System in Learning and Memory. In E.D. Levin & J.J. Buccafusco (Eds.), Animal Models of Cognitive Impairment (37-48). Boca Raton: CRC Press.

Sacks, O. (1985). Murder. The Man who Mistook his Wife for a Hat (161-165). New York: Touchstone.