A new study published in the Journal of Psychiatric Research has found that a single session of high intensity interval training can temporarily increase levels of brain-derived neurotrophic factor (BDNF), a brain protein important for memory and learning, in individuals with post-traumatic stress disorder (PTSD). However, the research also found that neither high intensity nor low intensity exercise led to sustained increases in BDNF over a period of nearly two weeks. These findings suggest that while intense exercise might offer a short-term biological boost, more research is needed to understand how exercise can best be used to support long-term brain health in people with PTSD.

PTSD is a mental health condition that can develop after a person experiences or witnesses a terrifying event. These events can include serious accidents, physical or sexual assault, war, natural disasters, or other life-threatening situations. People with PTSD can experience a range of distressing symptoms that significantly interfere with their daily lives. These symptoms can include re-experiencing the trauma through nightmares or flashbacks, avoiding reminders of the trauma, negative changes in mood and thinking, and feeling constantly on edge or hyperaroused. While effective treatments like therapy exist, many individuals with PTSD continue to struggle with their symptoms, highlighting the need for additional and complementary approaches to care.

Researchers are increasingly interested in biological factors that might contribute to PTSD and its treatment. One such factor is BDNF, a protein that acts like fertilizer for the brain, helping to support the survival, growth, and connection of brain cells. It plays a key role in brain plasticity, which is the brain’s ability to reorganize itself by forming new neural connections throughout life.

Studies have shown that individuals with PTSD often have lower levels of BDNF in their bloodstream compared to people without the condition. This reduced level of BDNF may play a role in some of the difficulties faced by individuals with PTSD, such as problems with processing and overcoming traumatic memories. For example, BDNF is thought to be involved in the brain’s ability to ‘extinguish’ fear memories – to learn that a previously feared situation is now safe. If BDNF levels are low, this process might be impaired, potentially contributing to the persistent fear and anxiety seen in PTSD.

Because of BDNF’s importance in brain health and its potential link to PTSD, researchers are eager to explore ways to increase BDNF levels in individuals with this condition, hoping to find new avenues for improving treatment and recovery. Given that physical exercise has been shown to boost BDNF in other populations, the researchers sought to determine whether exercise could be a way to raise BDNF levels and potentially alleviate PTSD symptoms.

To conduct their research, the team recruited 40 adults who had been diagnosed with PTSD. Participants were carefully screened to ensure they met specific criteria, including having a confirmed diagnosis of PTSD according to established guidelines. Individuals with certain other serious mental health conditions like schizophrenia or bipolar disorder, those with current substance abuse issues, or those at immediate risk of suicide were excluded from the study. People who were already engaging in a significant amount of regular exercise were also not included, to ensure that the exercise interventions in the study would be the primary factor influencing any changes. Importantly, individuals who were taking psychiatric medications or undergoing psychotherapy were allowed to participate, as long as their medication doses and therapy type had been stable for at least two months prior to the study.

Once enrolled, participants underwent a thorough physical examination, including a fitness test to determine their individual exercise capacity and maximum heart rate. This personalized assessment was important to tailor the exercise programs to each person’s fitness level and to ensure safety. Participants were then randomly assigned to one of two exercise groups: high intensity interval training or low intensity training. The exercise period lasted for 12 days, with participants engaging in exercise sessions every other day, for a total of six sessions. Each session was 30 minutes long and consisted of a warm-up, 20 minutes of the assigned exercise type, and a cool-down period.

The high intensity interval training involved cycling on an exercise bike. During the high intensity intervals, participants were encouraged to cycle at a pace that elevated their heart rate to above 77% of their maximum heart rate. This high intensity period was followed by a recovery interval where they cycled at a lower intensity allowing their heart rate to drop below 77% of their maximum. Each high intensity interval training session included ten cycles of high intensity and recovery. The low intensity training was designed to be less strenuous. It consisted of a series of gentle movements and stability exercises inspired by yoga, but without the focus on breathing or mindfulness that is often part of yoga practice. The goal was to keep participants’ heart rates below 70% of their maximum during these sessions. Throughout all exercise sessions, participants wore heart rate monitors to ensure they were exercising at the correct intensity.

To measure BDNF levels, the researchers collected blood samples from participants on the first and last days of the exercise period. On each of these days, blood was drawn both before and immediately after the exercise session. These blood samples were carefully processed to measure the amount of BDNF in the serum, which is the liquid part of the blood. Because BDNF is also found in platelets, blood cells that help with clotting, the researchers also measured platelet counts in the participants’ blood and took these counts into account when analyzing the BDNF data, to get a more precise measure of BDNF levels. In addition to these biological measures, participants also completed a questionnaire each day to track their PTSD symptoms.

The study’s findings revealed that high intensity interval training did indeed lead to a short-term increase in BDNF levels. Immediately after a high intensity interval training session, participants in this group showed a significant rise in BDNF in their blood, both on the first and last days of the exercise period. This increase was observed even after accounting for platelet counts. In contrast, the low intensity training group did not experience a similar increase in BDNF levels after their exercise sessions.

However, the researchers also found that neither type of exercise, high intensity or low intensity, resulted in a sustained increase in BDNF levels over the 12-day exercise period. When comparing BDNF levels from the beginning to the end of the study, there was no significant change in either exercise group.

Finally, while the study explored whether the short-term increase in BDNF was related to improvements in PTSD symptoms, no strong link was found. There was a slight suggestion that individuals who experienced a larger increase in BDNF after exercise might also report slightly greater day-to-day improvements in their symptoms, but this trend was not statistically strong.

The researchers concluded that high intensity interval training “might be a beneficial form of exercise for individuals with PTSD regarding serum BDNF levels,” but “further studies are needed to investigate whether transient and long-term BDNF increase contributes to a reduction of PTSD symptoms.”

In particular, future research could build upon these findings by examining larger groups of individuals with PTSD and specifically considering potential gender differences in the response to exercise. Longer-term studies are also needed to investigate whether regular high intensity interval training, or other forms of exercise, can lead to sustained increases in BDNF and, importantly, whether these increases translate into meaningful reductions in PTSD symptoms over time. Understanding how exercise affects BDNF in individuals with PTSD could pave the way for developing more effective and personalized exercise interventions to support their recovery and well-being.

The study, “Effects of high intensity interval training on serum brain-derived neurotrophic factor in individuals with PTSD,” was authored by Annabell Jäger, Anima Pieper, Kathlen Priebe, Rainer Hellweg, Kristina Meyer, Sarah Herrmann, Bernd Wolfarth, Maximilian Grummt, Andreas Ströhle, and Nikola Schoofs.