What About Brain Activity During Relapse?
Despite a desire to avoid the substance and the strategies learned for avoiding relapse, intense cravings can often overwhelm the individual. Even with a full understanding of the risk of relapse and the associated consequences, the individual may find themselves unable to resist the cravings.
A study conducted by researchers at the Medical University of South Carolina (MUSC) focused on examining the brain response in animal models when a cue is encountered that was previously associated with substance use.
The study, which was supported by the National Institute on Drug Abuse used rats to investigate how reminders of past use of cocaine could hold a powerful influence over those that had experienced cocaine addiction. The researchers located a brain response that is associated with the encountering of a cue that the rats had previously associated with the self-administration of cocaine. The response did not occur when the cue was associated with a pleasurable, but non-drug, experience.
The brain response could be experienced in humans in a way that delivers a powerful craving. This craving may prevent the brain from using the tools used in treatment to access alternative choices. The response occurs in the nucleus accumbens, which is a sort of liaison between the brain’s motivational and decision-making circuits and the motor circuits.
The response is called synaptic potentiation, and it can make the nucleus accumbens neurons more sensitive to incoming cues. The increased sensitivity may lead to the initiation of relapse in a recovering addict.
The findings from the study could lead to treatment options designed to reduce the effects of synaptic potentiation in order to prevent relapse in recovering addicts.
While the study used a specific cue with the rats, the drug-associated cue could be anything that a recovering addict associates with their previous drug use. This may include a setting where they previously used the drug or a conversation that reminds them of a previous time when they were using drugs.
The MUSC researchers predicted that the cues associated with cocaine would trigger synaptic potentiation in the rats, which would then lead to a relapse-like response. In order to test the theory, the researchers exposed the rats to a three-stage exercise that would mimic the human experience of the use of cocaine, then the association with a cue, followed by withdrawal and then relapse.
The rats were kept in a chamber with a lever that, when pressed, would deliver cocaine along with a tone-and-light cue. After 10 days of cocaine use, the cocaine was eliminated along with the cue. The rats gradually stopped pressing the lever.
Two weeks after the removal of cocaine, the researchers reinstated only the tone-and-light cue. The rats went back to avidly pressing the lever, despite the absence of cocaine. The response of the rats to the reinstatement of the cue resembles the compulsive behaviors that often consume those who have relapsed following a recovery period.