An incredible new experimental study from University College London has found a specifically timed infusion of ketamine can effectively rewrite maladaptive reward memories. In this study a number of subjects with harmful alcohol behaviours significantly reduced their drinking for several months following a single ketamine treatment.
Ketamine was originally developed as a novel anaesthetic in the mid 20th century but its potent disassociative effects rendered it unsuitable for broad human uses. More recently the drug has been experiencing a renaissance after its rapid anti-depressant effects were discovered.
Following on from some landmark Russian research in the 1980s exploring ketamine’s potential for treating a variety of addictive disorders, including alcoholism, a new study is suggesting the drug can potentially disrupt the encoding of reward memories when administered after addictive urges have been primed.
“Learning is at the heart of why people become addicted to drugs or alcohol,” explains Ravi Das, lead author on the new research. “Essentially, the drug hijacks the brain’s in-built reward-learning system, so that you end up associating environmental ‘triggers’ with the drug. These produce an exaggerated desire to take the drug. Unfortunately, once these reward memories are established, it’s very difficult to re-learn more healthy associations, but it’s vital in order to prevent relapse.”
Based on the prior efficacy ketamine had shown treating alcoholism, the new research hypothesized the drug to have the capacity to rewrite maladaptive reward memories (MRMs) if administered at the moment the brain was reconsolidating those memories. To experimentally test this hypothesis the researchers recruited 90 subjects with harmful drinking behaviors. The subjects all self reported heavy drinking (an average consumption of 74 units of alcohol per week) but had no preexisting clinical diagnoses of alcoholism.
To activate a reward memory the researchers presented the subjects with a glass of beer. Before being allowed to drink the beer the subjects were tasked with rating their anticipated pleasure after viewing a series of drinking related images. To destabilize the reward memory the researchers unexpectedly took the beer away from the subjects before they could drink it. The idea is that this process would trigger the reconsolidation of an MRM, creating a short window of time where ketamine could be administered to disrupt the rewriting of the association.
The cohort was randomly split into three groups: one group received an active ketamine infusion immediately after the reward memory activation, another group received a placebo infusion after the memory activation, and a third group received a ketamine infusion in the absence of any MRM activation.
The results revealed the group receiving the ketamine after reward memory activation reported significant reductions in drinking days per week and overall volume of alcohol consumed. The results also impressively held strong for the entire nine-month follow-up period. Interestingly, the group receiving the ketamine without memory activation did report a reduction in drinking behaviors, however, those results were not as strong as those administered the drug alongside MRM activation.