Studying animals made way more sense as a way to trace how chronic drug use changes the brain, they thought — after all, how was Hurd going to parse the long-term effects from the trauma of the overdoses that killed the brain donors?
She waved her colleagues off. She wanted to know what was happening in human brains, not in mice.
So she began filling up freezers with slices of brain tissue from hundreds of overdose victims, most of them killed by too much cocaine.
“We had a lot of freezers, sadly,” said Hurd, who now runs the Addiction Institute at the Mount Sinai School of Medicine. And then, early in the 2000s, she noticed a tidal shift: Suddenly, the overdoses were dominated by heroin.
She saw the opioid crisis coming. Ever since, she’s been trying to figure out how to intervene — could she modify or reverse the way addiction changed the brains being studied in her lab?
Hurd has homed in on cannabidiol, one of the two main compounds plucked from the marijuana plant. She thinks it might hold the potential to curb cravings for heroin and other opioids.
She’s running against the wind. Cannabidiol is classified as a Schedule I drug, meaning the U.S. government thinks it carries severe safety concerns, no medicinal benefits, and a high risk of abuse. Even as a growing number of states legalize marijuana, the hard-line federal stance has made it difficult to do clinical research involving cannabis in this country.
But Hurd is throwing all of her weight into studying whether it can combat addiction. And she’s trying to rally other scientists to do the same, by creating a consortium to conduct cannabidiol clinical trials across the globe.
“If this is something that could be potentially beneficial, and there’s an indication that it could be beneficial,” Hurd said in an interview, “why not put all hands on deck?”
Hurd has the reputation and academic standing to pull this off — last fall, she was named to the prestigious National Academy of Medicine, along with dozens of other top-tier researchers.
More than that, she has determination: On the front of her computer screen, she’s stuck up a yellow Post-it note that says, “GAIN CONTROL.” Only she’s crossed out “GAIN,” and replaced it with “TAKE.”
Unraveling the biology of addiction
Hurd has always had what she calls a “pure fascination” with the brain. Her own bounces quickly from one thought to the next, sometimes leaving threads unfinished for the sake of starting a new one. One idea may spin off into a dozen new ones. During a recent interview, she jumped from why she finds outliers in science so intriguing to why she loves murder mysteries (Alfred Hitchcock is a personal favorite).
That mental multitasking is mirrored in her lab, where her team is working on a slew of projects, from how chronic drug use restructures the brain to how the brain’s circuits play a role in psychiatric disease.
“My research, unfortunately, reflects me,” she said.
Her mind is constantly hunting for new ideas in unlikely, often difficult places — like on the list of Schedule I drugs.
Past studies have shown that cannabidiol works on a number of brain circuits involved in addiction and drug-seeking behavior. That’s made it an exciting pharmacological target — but the data, by and large, have just been preliminary and unpersuasive. Hurd started looking for more concrete evidence on cannabidiol.
“If this is something that could be potentially beneficial, and there’s an indication that it could be beneficial, why not put all hands on deck?”
The compound is one of the two main cannabinoids found in the marijuana plant, the other being tetrahydrocannabinol, or THC. But unlike THC, cannabidiol doesn’t get people high. Scientists are studying whether the compound can treat conditions such as epilepsy and anxiety. Hurd is testing whether cannabidiol can cut down on cravings in patients who are addicted to opioids — and in turn, can prevent relapse.
In her research on animals, the compound has decreased cravings and anxiety without producing any psychoactive effects. But she’s not sure why, exactly, it’s working. So at the same time, she’s orchestrating studies to delve into the biology that underlies addiction.
Some quick background: The neurons in the brain talk to each other through neurotransmitters such as dopamine, serotonin, and endocannabinoids. Those chemical messengers ferry information between brain cells through a synapse, which is the intersection between two neurons. Drugs like heroin are like a car crash — they damage those synapses to the point that other cars can’t get through.
The hurdles are enormous’
Studying cannabidiol is daunting, and not just because the brain is so complex. To use cannabidiol or any part of the cannabis plant for research, a scientist has to get a special license from the Drug Enforcement Administration, which can take years. Then, scientists have to get approval from the Food and Drug Administration to administer it to patients.
“The hurdles are enormous,” said Margaret Haney, a neurobiologist at Columbia University who studies cannabis use disorder and the therapeutic potential of cannabinoids in humans. Haney has to keep the cannabis used in her trials in a gun safe that’s stashed inside a freezer that’s sitting in a special room in her lab that can only be accessed with her fingerprint. That’s routine for cannabis research.
And patients who are enrolled in clinical trials involving cannabis have to come to the lab of the researcher who holds a DEA license to get the drug, which isn’t always doable for individuals with serious medical conditions.
“Our hands are tied even though cannabidiol is not addictive,” Hurd said. But because it derives from the cannabis plant, the government classifies it as a Schedule I drug — like heroin, LSD, ecstasy, and peyote — which are considered to be harmful and have no medicinal value.