by University of Tsukuba

Credit: CC0 Public Domain

Post-traumatic stress disorder (PTSD) is a common mental disorder caused by severe stress. Recent research suggests that exercise can help prevent and treat PTSD. However, the specific effects of light-intensity exercise (LIE) on PTSD symptoms remain unclear.

One hypothesis is that the brain-derived neurotrophic factor (BDNF) plays a crucial role in eliminating fear memories. This molecule's expression in the hippocampus, the region of the brain responsible for memory and learning, is known to increase with habitual exercise.

In this study, researchers used an animal treadmill exercise model specifically designed to determine exercise intensity based on lactate threshold. This model allowed them to explore whether regular exercise can erase fear memories and whether BDNF is involved in this process.

The research is published in the journal Medicine & Science in Sports & Exercise.

In the experiment, rats were initially placed in a chamber and subjected to mild electrical stimulation to induce fear memories. Subsequently, the rats underwent LIE training for four weeks. After the training period, the rats were placed back in the chamber and their behavior was observed and compared with that of rats that did not undergo exercise training.

Typically, rats exhibit freezing behavior when experiencing fear. Initially, all rats demonstrated fear-induced freezing behavior. However, rats that were regularly exercised gradually became more active. This indicates that regular exercise facilitated the erasure of fear memories.

Furthermore, when BDNF signaling was inhibited in the rats through the administration of a specific drug, the effects of exercise on fear memory erasure disappeared, indicating that BDNF signaling is involved in the erasure of fear memories via LIE.

The aforementioned findings indicate that PTSD psychiatric symptoms caused by intense stress may be alleviated via continuous LIE because LIE enhances BDNF activity in the hippocampus.

PTSD patients frequently experience concurrent depressive symptoms and struggle to maintain a consistent exercise routine. The findings of this study show that even LIE can effectively erase fear memories. Moreover, these findings may pave the way for new exercise-based treatment and prevention programs with high patient adherence.

More information: Ryo Shimoda et al, Accelerated Fear Extinction by Regular Light-Intensity Exercise: A Possible Role of Hippocampal BDNF-TrkB Signaling, Medicine & Science in Sports & Exercise (2024). DOI: 10.1249/MSS.0000000000003312

Journal information: Medicine & Science in Sports & Exercise 

Provided by University of Tsukuba