This could radically change the recovery process of addiction.
Addiction takes over the body in a number of ways, and the excruciating withdrawal symptoms can make drug habits particularly hard to kick. Giving up a euphoric high for a torturous low certainly makes the recovery process even more trying.
Withdrawal symptoms can range anywhere from anxiety and depression to nausea, vomiting, cold sweats, and diarrhea. When addicts associate the pain of withdrawal with the loss of drug use, experts say this can create an urge to use that is as strong as the drug’s “high” itself.
Scientists have been trying to find the golden cure for addiction for decades, but the disease is complex and subjective to each individual. However, in an exciting breakthrough, researchers at Stanford University have discovered how to use optogenetics — the combination of light and genetics to control events within specific cells of living tissue — to suppress the urges to use a drug at their origin within the brain.
“Most research that studies drug addiction is focused on the reward pathway because that is the reason you start to take drugs, but people who really get addicted also take drugs to get rid of the withdrawal effect. This is especially important in opiate addiction,” lead investigator Xiaoke Chen, assistant professor of biology at Stanford University, said in a press release.
The researchers pinpointed the nerve centers in the brain that react to the painful withdrawal stimuli and successfully controlled the nerve centers in morphine-dependent mice in order to eliminate the negative reactions to opiate withdrawal symptoms. Pretty impressive!
First, the researchers studied the nucleus accumbens, a group of neurons in the brain that is commonly associated with drug reward. It has previously been shown that the nucleus accumbens responds to negative stimuli like drug withdrawal.
Next, the researchers tagged certain proteins with fluorescence so they could visualize the behavior of the nucleus accumbens. The proteins illuminated two brain centers as well as the pathways that connect them, clearly demonstrating that a small group of cells in the paraventricular nucleus of the thalamus (PVT) sends signals to the nucleus accumbens.
Then, using optogenetics to switch neurons on or off via light from optical fibers, the scientists tested the link between the nucleus accumbens and the PVT to prove that it is responsible for withdrawal symptoms.
According to Chen, chronic drug use strengthens the PVT-to-nucleus-accumbens pathway, and this might be the reason for the intense withdrawal responses that come with addiction. Amazingly, the optogenetic tools enabled the scientists to revert the pathway to its original synaptic strength, thus erasing the effects of the drug. Even though the research was conducted in mice instead of humans, the results suggest that reprogramming this circuit could be key in treating opiate addictions.
“This is a knowledge-guided treatment. We not only identified a new pathway, but we actually established the causality between the plasticic [sic] change in this single synapse and opioid withdrawal symptoms,” Chen says. “Drugs affect many places throughout the brain, but here we manipulate this single synapse and can get rid of this drug effect.”
Chen says that this research could foster promising future treatments, not only for people struggling with addiction, but for those battling anxiety and depression as well.
The study is published in the journal Nature.