Years into sobriety, seemingly innocent stimuli — like songs, smells or specific visuals — can trigger memories of earlier drug use and an intense craving that can cause even a long-recovered addict to relapse.
But what if those memories could be manipulated to be less triggering?
“If we can dampen that craving by weakening the drug memories,” Washington State University professor Rita Fuchs said, “we would have a better chance of interfering with the whole process of relapse.”
Fuchs was recently awarded a nearly $2.9 million grant from the National Institute on Drug Abuse that will allow her to further explore how the brain retrieves and reforms memories of cocaine use and how the process can be manipulated to reduce occurrences of relapse. She is hopeful the research will eventually lead to more effective treatments for substance abuse disorders.
Most research into the field has focused on the mesocorticolimbic system that plays a role in the acute pleasurable effects of drugs of abuse. Fuchs’ efforts are concentrated on an understudied area, the contributions of long-term memory maintenance mechanisms to substance use disorders.
Along with her team of graduate and undergraduate students and her collaborators in the lab of fellow Integrative Physiology and Neuroscience professor David Rossi, Fuchs is particularly interested in engrams — or small circuits of neurons that encode memories — in the hippocampus region of the brain.
The team plans to use special viruses to precisely identify, map out and alter specific engrams storing memories associated with cocaine use. The viruses will allow the researchers to better study and manipulate only the cocaine engrams cells without affecting any neighboring cells in the brain.
“We hope this will help us to understand how these engrams operate, at least in the hippocampus, but we also realize that engrams for the same memory may be represented in different parts of the brain,” Fuchs said. “The next step will be to spread out to other brain regions and try to essentially keep connecting the dots to understand the same phenomenon at higher and higher levels.”
When cocaine-related memories are triggered, Fuchs says they must be retrieved from long-term memory. During retrieval, the memories become destabilized and need to be reconsolidated into long-term memory stores to be maintained, updated and potentially strengthened.
Fuchs’ earlier research has shown that interference during the reconsolidation phase can weaken cocaine-related memories and reduces drug craving.
“If we can put the memory in that labile state, then we can manipulate it and make it less maladaptive for the individual,” she said.
Similar methods have been shown to be effective at treating human patients for post-traumatic stress disorder. While the subject still has the memory, it has been manipulated in such a way that the emotional dimension is no longer as deep.
“PTSD users usually compare it to looking at a postcard of a battle scene, as opposed to feeling like they’re being transported back into the battle,” Fuchs said. “So, it’s not complete amnesia, it’s just an amnesia of the emotional aspect of the memory.”
Fuchs joined the College of Veterinary Medicine in 2013 and has since focused her research on understanding how environmental stimuli affect drug-seeking behaviors, cognition and physiological functions related to drug addiction.