Heart Rate Variability, Stress Response, and PTSD

In post-traumatic stress disorder (PTSD), physiological arousal is increased when a person is reminded of their traumatic experience.  This is somewhat unsurprising. 

An over activated sympathetic nervous system almost certainly plays a role in this. However, under activation of the parasympathetic nervous system, or “low vagal tone,” might be equally important. 

The goal of the paper I’m sharing this week was to examine these two components and determine which might be responsible for the enhanced stress response in PTSD.

As with most things, the answer is likely “they both matter.” But here is what they found.

Low Heart Rate Variability Linked to Enhanced Stress Response

(Read the Full Summary Here)

They measured high-frequency heart rate variability (HRV) as a marker of parasympathetic tone. Then, the participants were read a trauma script and their physiological response was recorded.

Results showed that patients with a higher baseline HRV did not experience as much stress.  The subjects with lower HRV showed a higher heart rate peak, followed by a slower deceleration of heart rate.  That is, they showed an elevated stress response.

The patients with lower baseline HRV also had longer half-recovery times, meaning that their stress response was not only elevated, but also prolonged. 

These findings suggest that low parasympathetic tone, rather than just increased sympathetic activity, might help explain the increased physiological stress response in PTSD.

Two Takeaways

1. HRV measurements might provide insight into the severity of a person’s PTSD and predict how well they respond to stress.

2. Slow breathing is one of the easiest ways to improve HRV, both immediately and long term.

If HRV predicts the stress response, and HRV can be increased via breathing exercises, it is conceivable that breathing practices could improve stress resiliency in PTSD.  (In fact, a 2013 study found that a yoga breathing program significantly improves PTSD symptoms in Australian Vietnam veterans.)

Finally (and importantly), these takeaways might be applicable to conditions other than PTSD, such as anxiety disorder, cardiovascular disease, and diabetes.

In good breath,
Nick

Yoga breathing significantly reduces PTSD in veterans

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For those of you who celebrate, I hope you had a Happy Thanksgiving!

I ate enough to almost start mouth breathing…

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Before we get into this week’s research, I don’t want you to get the impression that breathing will cure PTSD. This study examined using breathing as complementary therapy, one that could be integrated as part of a complete treatment plan for PTSD. And they found encouraging results.

(Read the Full Summary of the Study Here)

The researchers studied 25 male Vietnam veterans from Australia. They were guided through a 5-day yoga program that consisted of breathing, mobility, asanas, and group therapy. Thus, there were several components to the study beyond breathing.

After the extensive 5-day training, the participants went once a week for 1 month, then once a month for 5 more months. In between sessions, they were encouraged to practice yoga breathing for 30 minutes every day. The study lasted a total of 6 months.

The researchers examined how the program affected the patients’ CAPS (Clinician Administered PTSD Scale) score, a 30-question interview that assesses PTSD severity. Scores range from 0 to 88, with higher values indicating more severe PTSD symptoms.

The average CAPS score at the beginning of the study was 56.3.  At week 6, the average score had significantly fallen to 42.1.  Finally, at the end of the 6 months, the average score had dropped to 26.2.

That’s pretty amazing. And this was with no changes to the participants medication.

Because yoga breathing is simple and has essentially no negative side effects, it could potentially be incorporated into the military health care system and be a valuable complementary therapy for PTSD.

Until that happens, let’s hope more scientific studies are conducted to assess the effectiveness of breathing programs for PTSD and to provide practical guidelines for using it as a complementary therapy.

In good breath,
Nick

P.S. HHPF is a nonprofit organization making major scientific advances with breathing therapies for stress in our military and first responder populations.