‘Erasing’ memories associated with drugs can help prevent relapse of addiction

Research around addiction often points to the reward of a “high” as the primary motivation for drug use and relapse. However, it is often acute withdrawal symptoms, including nausea, vomiting, pain, and cramps, that drives a return to drugs for relief.

The most difficult part of addiction treatment is preventing relapse, especially for opioids. Opioid withdrawal symptoms are severe and relapse among users is common.

Both the “stop” reward and the relief of painful withdrawal symptoms can serve as powerful memory cues that trigger a relapse.

Researchers at the Shenzhen Institute of Advanced Technology (SIAT) of the Chinese Academy of Sciences and Stanford University disrupted the brain pathway responsible for memories associated with morphine in mice, that is, “erasing” memory associated with the drug of the brain.

The study was published in Neuron July 16.

The researchers put the mice in a two-sided chamber to train. They were given saline on one side and a small dose of morphine on the other side. After five days, the mice developed a compulsive preference for the camera with morphine and were considered addicts.

Then, by using the light from a fiber optic, the scientists could turn off the paraventricular thalamus (PVT) pathway to ease opioid withdrawal symptoms.

When the PVT withdrawal pathway was turned off or silenced, the mice’s preference for the drug-associated chamber disappeared. If tested a day later, when the withdrawal route could theoretically function again and environmental cues could reactivate memory, the scientists were surprised to find that the mice still showed no preference for the camera associated with the drug.

“Our data suggests that after silencing this PVT pathway, environmental signals will not function to reactivate this memory,” said Chen Xiaoke, an associate professor of biology at Stanford University.

Even when morphine was reintroduced into the chamber, the mice still did not preferentially go there, and this was true even two weeks later. It was as if the animals had completely forgotten the effects, both good and bad, of the drug.

“Our success in relapse prevention in rodents could one day translate into long-lasting treatment of opioid addiction in people,” said Zhu Yingjie of SIAT, the corresponding co-author of this study.