How Gene Therapy Could Revolutionize Addiction Treatment


This episode of SciShow is sponsored by the
American Society of Gene and Cell Therapy. [♪ INTRO] If you’ve heard anything about gene therapy,
it’s probably how it can treat certain illnesses and disorders. But while that’s totally true — and amazing
— that is not the only way it can be used. Recently, scientists have been paving the
way for gene therapy to be used as a treatment for drug addiction and overdose. Most of these studies have specifically focused
on cocaine, and some of the more promising ones suggest that gene therapy might not just
be able to treat overdoses… it might also be able to help prevent relapse. This kind of treatment is still very early
in the development cycle, but if we can show it safely works in humans, it might just revolutionize
the way we treat addiction. Cocaine is one of the more common illegal
drugs out there, and it works by causing large amounts of dopamine to build up in the brain. Dopamine is one of the molecules involved
in the body’s reward system, so having a ton of it floating around causes feelings
like euphoria. Over time, though, the brain can get used
to having all that extra dopamine, which makes the drug hard to permanently quit. It also means that people need to take more
and more of the drug to get the same high. But in large doses, cocaine can be fatal. It can cause irregular heart rhythms, seizures,
trouble breathing, or strokes. And in 2017, there were an estimated 14,000
overdoses in the U.S. involving the drug. There aren’t any great treatments for this
addiction, either, although there are plenty in the works. Many involve changing the brain’s response
to chemicals like dopamine. But gene therapy treatments go even deeper. They typically center around a protein called
BChE. It’s made naturally by the liver and breaks
down compounds called esters, which sort of “reset” activated neurons and allow muscles
to relax. It can be also used to protect people against
poisons that disrupt nerve functions, like nerve gas. But it can break down cocaine, too. The problem is, BChE works way too slowly
to treat addictions and overdoses, allowing almost all of a typical dose of cocaine to
make it to the brain’s reward centers. So over the years, scientists have been working
to modify the protein’s structure so that it’s even faster and more efficient. Using methods like computer simulations, they’ve
been pretty successful so far, and some of their modified proteins can inactivate cocaine
within seconds of it showing up in the blood. But there’s still the whole issue of how
to deliver the new protein. And that’s where gene therapy really comes
in. In this method, scientists specially engineer
a virus called a vector, taking out the parts that cause disease and inserting information
that tells cells to start making modified BChE. So far, it hasn’t been tested in humans
— most of the work has been in rodent models — but there have been multiple experiments
in the last decade, and they’ve generally been really successful. Like, not only does this treatment seem to
work, but from what scientists can tell, it also doesn’t seem to have any negative side
effects. One of the more significant papers in this
field comes from the journal Vaccine in 2014. In the study, there were two groups of mice. One group was injected with trillions of vector
particles that told their bodies to produce an enhanced version of BChE. The other group was either injected with a
harmless saline solution or a vector without BChE as a control. Based on the team’s special mouse-monitoring
system, which looked at things like motor activity and oxygen consumption, the researchers
found that the mice didn’t seem to function any different with large amounts of modified
BChE in their bodies. But the real test is what happened when those
animals were injected with cocaine. The scientists gave them what would have easily
been a lethal dose of the drug, and waited to see what happened. And they found that… like, nothing happened. The mice that received the modified BChE vector
didn’t show any changes in activity, which likely meant the protein broke down drug molecules
too quickly for them to have any effect. What’s significant about this treatment
isn’t just that it can protect against overdoses, either. It may also be able to help people quit the
drug, by preventing someone from feeling its euphoric effects and, therefore, decreasing
their drive to use it. In the same 2014 experiment, the scientists
found that the levels of modified BChE remained high in the mice’s blood for 8 to 16 months
after the initial vector injection. If those results can be translated to humans,
it means that even if someone recovering from addiction does slip up and take the drug,
they wouldn’t feel its effects — maybe even years after the treatment. And that would likely help them quit for good. Right now, it’s definitely an “if”,
though. Rodent models of addiction are generally pretty
accurate, but they’re not perfect. And researchers want to make sure they’re
totally confident that these modified proteins wouldn’t have unexpected effects on the
brain. So for now, they’ll keep running tests on
animal models to see what happens. The good news is, experiments with BChE have
been effective and safe in everything from rodents to nonhuman primates. So it’s not impossible that these treatments
will make their way into human medicine at some point. Also, although it has been a major research
area, gene therapy isn’t just for cocaine. Researchers have been studying how to use
this technique to treat other addictions, like alcohol or meth. And similar treatments could even be used
to fight opioid addictions — although that problem is a bit more complicated, because
there are times when people do need strong painkillers. Also, it’s tricky because not all drugs
are broken down by BChE, so scientists have to develop different methods for each new
addiction. For example, a 2017 paper actually used gene
therapy to enhance the negative effects of drinking, like dizziness, in order to drive
mice away from it. Still, even though the exact way of using
gene therapy might change from case to case, the tool itself is valuable and has a ton
of applications. And if we learn it’s safe to start treating
addiction this way in humans, it could have the potential to save tens of thousands of
lives. If you’re interested in learning more about
developments in this field, or other types of gene therapy and how they work, you can
check out the new patient education portal from the American Society of Gene and Cell
Therapy. It’s a really comprehensive resource full
of clear explanations and easy-to-follow summaries — and it’s all completely free. And to no one’s surprise, we here at SciShow
are big fans of free online education around here, especially when the content is as interesting
as this. To check the portal out for yourself, just
head over to asgct.org/education, or just follow the link in the description below. [♪ OUTRO]

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