Implementing Chronic Exercise After the Completion of Extinction Training in Mice Shows Promise in Reducing the Return of Fear in the Long Term

Post-traumatic stress disorder (PTSD) is a prevalent mental health condition that affects a wide variety of populations. One of the first-line treatments for this disorder is prolonged- exposure therapy (PE), a therapy that has produced inconsistent results with high rates of fear return over time. Fear conditioning, a process that relates to PTSD, has been studied in animals for many years. An additional component of this procedure, referred to as extinction training, is similar to the methods behind PE, and as such, different interventions can be tested in animals in hopes of finding ways to improve the success of the therapy in humans. In the past, researchers have tried to use exercise as an intervention, based on experiments demonstrating its ability to improve learning by strengthening the consolidation of memories. Chronic exercise implemented directly after fear conditioning, and before extinction, has been found to increase rather than to reduce the magnitude of the fearful response when tested after the passage of time. In our study, we sought to determine if altering the timing of chronic exercise would have a different effect. We ran three groups through a fear conditioning and extinction paradigm, with one group remaining sedentary for the entire experiment, a second group beginning to exercise directly after fear conditioning, and a third group beginning to exercise after the completion of extinction. Our results indicated a significant overall decrease in magnitude of the return of fear within the group that began exercising after extinction when compared to both the sedentary group and the group that began exercise after fear conditioning. These results show that there is promise in using this method for improving the long-term success of exposure-based therapies for PTSD. Continued adjustments to the procedure could lead to a more dependable method that could be employed in human populations