For those of you who live under a rock, zombies are real. Not in the sense of zombies from World War Z or The Walking Dead. I’m talking about the neuroanatomic and pathophysiologic properties that underlie people who suffer from symptoms of zombie-ism: Meaning symptoms like global aphasia, inattention, disinhibition, ataxic gait, amnesia, insomnia, and disturbances in hunger (not to mention what is appropriate to feed on). The question is, does a neurologic disorder mimic these symptoms? And if so, what?
Before you even listen to the show, know this: Comparisons will be made between various neurologic diseases and zombie-ism. If you or someone you know has a neurologic disorder, or if you find this comparison crude and offensive, this episode is not for you. But if you’re a zombie fanatic, and your skin is as thick as your skull, go ahead and click play. You’ll find the next 24 minutes well worth your while.
This week I am joined by Dr. Brian Hanrahan, a senior neurology resident from the University of Pittsburgh Medical Center. He previously joined us for a segment on First Seizure of Life, where (arguably) he contributed far more intellectual content than he has this week. He returns this week to share some insights into his true passion: zombies. In fact, he has lectured on this subject every year for the past 5 years–so I would certainly consider him an expert on the topic.
Much of the data you’ll find on zombies has to do with parasitism. Viruses, bacteria and parasites use host organisms to complete their lifecycle. These infectious agents are masters of host manipulation, able to hijack host processes to replicate and transmit to the next host. While we tend to think of infections as just making us sick, they are also capable of changing our behavior. In fact, many infectious agents are able to mediate host behavior in ways that can enhance transmission of the disease. The Cordyceps fungus is one example (right), and toxoplasma gondii is another. When toxoplasma gondii infects the intermediate host, rodents, it reduces the survival instinct of the infected rodent to avoid cats–and therefore “complete its life cycle”, as Dr. Hanrahan explains. This permits the parasite to infect its next host, the cat, and thrive in the environment. At the most basic level, whatever pathogenic agent that affects the central nervous system must influence the host organism’s behavior.
Toxic states may also explain zombie-like behaviors, especially in humans. One of the earliest descriptions of such a toxin originates in Haitian folklore. “Zombie” itself comes from the Haitian creole word, zonbi, describing the reanimated body of a deceased person. It was thought that in the early nineteenth century, Haitian “necromancers” would concoct a solution containing two ingredients–tetrodotoxin (a potent neuromuscular paralytic) and a naturally occurring anticholinergic agent–which would place the individual into a sort of hypoactive delirium, much like what we see in classic zombie movies such as the Dawn of the Dead (1978), Resident Evil (2002), and Zombieland (2009). This past year, a similar “zombie” state was reported in the New England Journal of Medicine in patients who consumed a THC analogue called AMB-FUBINACA. Reportedly 85 times more potent than common marijuana, AMB-FUBINACA caused a hypoactive delirium without the typical vital sign abnormalities (tachycardia, fever, hypertension, diaphoresis) observed in patients toxic from marijuana consumption. The result: 9 hours of zombie-ism.
But some zombie states may result in more aggression, hyperactive delirium, and violence. These symptoms are demonstrated by zombie characters from the films 28 Days Later (2002), I am Legend (2007) and World War Z (2013). Intoxication with bath salts has resulted in this classic symptom arrangement. In 2012, one consumer of bath salts went ballistic. According to locals in Louisiana who filmed the event, the subject assaulted a homeless man and literal chewed his face and eyes off. When approached by police, he was snarling and did not respond to commands. Eventually, the gentleman was shot and killed. (If you want to have nightmares, click this link to see ABC’s follow up story on the survivor of the attack.) A similar outbreak was observed in Louisiana that same year.
In addition to the more scientifically sound explanations behind zombie-ism, several scientists and neurologists have taken a fair bit of creative license to describe zombie neuroscience. Dr. Steven Schlozman’s book, Zombie Autopsies, is not unlike the story presented in the previously mentioned 2007 film, I am Legend (based on the 1954 novel by Richard Matheson). In both the film, I am Legend, and the book, Zombie Autopsies, the protagonist has committed his life to the study of these undead creatures. In Zombie Autopsies, Dr. Stanley Blum—who is infected by the zombie virus—studies zombies as if they were patients suffering from a neurologic disease, and he stratifies them based on severity of symptoms.
- Stage I Onset of extreme hunger with coexisting fever and respiratory symptoms. Cognitive lucidity is maintaining. Lasts from 2 minutes to 3 days.
- Stage II Worsening fever. Cognitive decline begins with confusion and delirium. Hunger intensifies. Balance begins to suffer. Lucidity impaired. Lasts from one to 24 hours.
- Stage III Frequent falls and increased aggressive behavior. Mild aphasia. Severe delirium and apathy. Lasts less than 4 hours.
- Stage IV Officially categorized as “No longer human”. Profoundly hyper-aggressive behavior. Global aphasia. Complete loss of awareness.
I will refer you to the episode for more information regarding the neurologic substrate hypothetically observed in zombies, and which neurologic disorders zombie-ism most closely mimics. Worth mentioning in the last minute is the fact that both the Centers for Disease Control and Prevention AND the American Red Cross BOTH have zombie apocalypse action plans. While they are more of an instrument to raise awareness about national and international emergencies, it’s still funny to read. So I’d recommend you check out these sites, after you’ve listened to our show this week.
BrainWaves’ podcasts and online content are intended for medical education (and entertainment) purposes only and should not be used for routine clinical decision making. Featured image from https://www.flickr.com/photos/dhollister/2596483147/ under a CC license.
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