Changing Memory Pattern Could Break Drug Addiction

Author: Allie Montgomery

There is now hope for people that are addicted to drugs to reclaim their life. By using a chemical that blocks the creation of memories, researchers have prevented lab rats that were addicted to cocaine from needing a fix. The hope is that physicians may be able to one day give humans some version of this chemical to help stop cocaine addiction in its tracks.

An experimental psychologist at the University of Cambridge in England, Barry Everitt, focused his team's efforts primarily on proteins called NMDA-type glutamate receptors in the brains of the rats. The previous work done on addiction and post-traumatic stress has shown that these types of proteins, which are found on the surface of cells in the brain, are essential to the formation of memory. The receptors are also crucial to reconsolidating our memory as well as moving it from its original storage area in long-term memory to regions of the brain that hand short-term memory.

The researchers on this project will report their findings in the Journal of Neuroscience. The scientists put the lab rats in a cage with a lever in it for a couple of hours daily. When the rats would push the lever, a light would come on and a cocaine solution would then be dispensed to the rats. The rats then began to associate the light that they saw to the cocaine.

After a couple of weeks of the rats being forced to stay sober, the animals were returned to the same cages. Before being returned to the cage, some of the rats received injections of an experimental drug that is used to block NMDA-type glutamate receptors in the amygdala, a region of the brain that has been implicated in memories that are drug-associated.

Both the rats that were treated and untreated, when placed back in the cage, would press the lever again and again. The light would come on as usual but no cocaine would be given to them. The untreated rats continued unfazed, hoping that the cocaine would eventually come out. For the rats that were treated, however, Everitt says, "They press the lever, but it doesn't do anything, so they stop." The rats seemed to forget that the lights in the cage meant that the cocaine was on its way for up to four weeks after only one treatment of the experimental drug.

The scientists suggest that by disrupting the recollection of a memory that is drug-associated, a person that abuses drugs may be able to break the connection between the cues in that environment and the need for the person to have the drugs. Sometimes these particular cues can be quite closely associated to home, possibly a family member or loved one.

A neurobiologist at the National Institute on Drug Abuse in Bethesda, Maryland, Yavin Shaham, said that the work is an example of "basic research that can be readily translated to the treatment of cocaine addiction in humans."

With no medications on the market today that are approved to specifically treat a cocaine addiction, most treatments rely on behavioral therapy. According to Everitt, these therapies often involve exposing the addicts to cues that they would normally associate with drug use, but in the absence of the illegal substance. Once the addict is recovered, when they encounter these cues back in their normal lives, they often relapse. Everitt suggests that using an NMDA-type glutamate receptor blocker in the clinic could improve that type of treatment.