Researchers have identified the cause of a drug-induced 'zombie' outbreak in New York last July, pinning the blame on the chemical AMB-FUBINACA – a custom-made designer drug that's known to be a public health concern.
This is the first time that experts have properly analysed the synthetic cannabinoid, which has a street name of 'AK-47 24 Karat Gold', and is said to be 85 times stronger than cannabis, causing slow movements, sluggish responses, and zombie-like groans.
During the July 12 incident in Brooklyn last year, emergency responders found 33 people, "all of whom had a degree of altered mental status that was described by bystanders as 'zombie-like'," the researchers write in their paper.
This mass intoxication saw affected people staring blankly and responding to medics slowly, sometimes while groaning.
Now, a new analysis of blood and urine samples – taken from eight of the affected patients admitted to hospital – shows that the zombie-like symptoms were due to overdosing on AMB-FUBINACA.
The researchers – representing law enforcement agencies and other institutions – hope their findings can help experts deal with similar overdoses in the future, and will educate the public about the dangers of these increasingly popular synthetic drugs.
"As the number and complexity of new psychoactive substances increases, this type of coordination among multiple agencies is important," the researchers explain.
It's harder to identify and analyse these kind of synthetic, designer substances than conventional drugs like cocaine and cannabis, as they don't always show up in standard toxicology tests.
This is because they're custom-made, and don't show the standard chemical traits that toxicology researchers usually look for.
In the Brooklyn incident, the index patient – the first person to be medically studied – was a 28-year-old male wearing a "blank stare" and moving his limbs mechanically.
But despite the zombie-like behaviour, a lot of his vital signs, including heart and respiratory rates, were normal.
To investigate further, scientists obtained samples from patients, and samples of AK-47 24 Karat Gold itself, before conducting what's called a liquid chromatography-mass spectrometry analysis.
This test uses motion to physically separate liquids and identify individual chemicals, revealing in this case that AMB-FUBINACA was behind the zombie outbreak.
While researchers have long used synthetic cannabinoids to study the nervous system, there's a worrying trend of recreational use that goes way beyond a few dozen people stumbling around on the sidewalk.
These cannabinoids are related to the key ingredient of marijuana, delta-9 tetrahydrocannabinol (THC), but they're made to be much stronger.
These mind-altering drugs are unregulated, and are widely available on the street and online. They can cause paranoia, confusion, and hallucinations, and have been linked to injuries and even deaths.
Getting a better understanding of the chemicals inside drugs like AK-47 24 Karat Gold is the first step in helping researchers address the dangers of these substances.
While these 'zombies' might not want to eat the flesh of the living, the consequences of these designer drugs can still be fatal.
Clinical chemist Roy Gerona from the University of California, San Francisco was involved in the new study, and warns that the threat is growing.
"No compound that has been made yet has the potential to kill thousands of people," he told Marc Santora at The New York Times. "But that is a scenario that is becoming more and more close to reality."
The findings are published in the New England Journal of Medicine.