Brain switch that makes people addicted to booze, alcohol or cigarettes identified by scientists
Brain switch that makes people addicted to drink, drugs or cigarettes is identified by scientists
Scientists say they have identified a brain switch that makes people addicted to alcohol, drugs and cigarettes.
The finding opens the door to developing treatments to combat addictions such as the opioid epidemic that has gripped the US.
Researchers in New York exposed mice to a certain sound before giving them either a reward – sugar water – or “punishment” – water.
Scans showed that the rodents’ amygdalae — which control emotions — began to “light up” in response to the sounds, as the animals learned what to expect.
The scan above shows an amygdala in a mouse brain (red dot on the left). Humans and mice carry this brain structure
Every human being has two amygdalae, regions of gray matter in the brain that help regulate emotions.
The two work together, but usually the left is associated with positive feelings, while the right manages negative emotions.
The tiny regions help us learn and remember, activate our fight-or-flight response, and even trigger the release of dopamine, the feel-good hormone.
In experiments at the Cold Spring Harbor lab, mice were trained to associate rapid sounds with the availability of water.
They also learned to associate slow-wave sounds with getting a dose of sugary water.
Brain scans showed that the lab rodents’ brains reacted differently depending on the sound they heard.
Lead author Dr. Bo Li, a neurologist who led the study, said: ‘This is completely new to us.
“These neurons really care about the nature of each individual stimulus. It’s almost a sensory realm.’
The US team also saw that the activation of the neurons increased more after training, suggesting that they are important for learning.
In further tests, the neurons were then inhibited to prevent mice from associating sounds with awards or punishments. They also suppressed normal dopamine responses.
The results showed that these mice had trouble learning the association between sounds and the type of food they were fed.
Dr. Li explained, “While previous research had linked the central amygdala to dopamine neurons, it was unclear exactly how they were connected.
‘We found that those neurons are necessary for normal function of dopamine neurons and are therefore important for reward learning.
“That’s direct evidence of how they regulate the function of dopamine neurons.”
Dr. Li and colleagues now plan to investigate the amygdala’s relationship to addiction.
Their trials are currently in mice, but could eventually move on to other animals, including monkeys, before reaching humans.
The research could one day lead to better treatments for opioid and methamphetamine addiction.
For the experiment, mice heard a signal before being offered water or sucrose. Scans showed that they had learned to associate specific sounds with specific rewards or punishments
Dr. Li said: ‘Our study provides a basis for developing more specific ways to regulate these neurons in different disease states.’
The US is currently in the throes of an opioid epidemic, with a record 108,000 Americans dying of drug overdoses.
The rising deaths are attributed to fentanyl, which is up to 100 times more potent than morphine, which is mixed with other drugs, with people unaware that the drug they are taking contains heroin.
There are also growing concerns about drugs being mixed with xylazine, an animal sedative, that naloxone overdose won’t work against.
The study is published in the journal Nature.