Post-traumatic Stress Disorder (PTSD) is a significant public health problem in individuals deployed to war. PTSD is a mental health condition linked to many other issues, including anger, insomnia, substance abuse, and chronic depression. Particularly, PTSD is linked to people who are deployed to war. Research shows that 19% of Vietnam-era combat veterans have a lifetime prevalence of PTSD and 13-15% of veterans of Iraq and Afghanistan. Overall, the prevalence of PTSD in the U.S. is 8%. 

What Is Heart Rate Variability?

HRV is the quantitative assessment of variation in heartbeat intervals and is a sensitive autonomic nervous system (ANS) function index. These minor variations add or subtract a fraction of a second between beats. The normal HRV by age varies, but the average HRV in men is 40 while the average HRV in women is 37.

Specialized devices can only detect heart rate variability. While it might be present in healthy individuals, it can still indicate various health problems, including heart conditions and mental health issues. An electrocardiogram (EKG) evaluates HRV measurement by attaching sensors to your skin. 

Your heart rate beats at specific rates, depending on what you’re doing. Your heart rate is slower when you’re resting or relaxed and faster when active, stressed, or in danger. Heart rate variability occurs based on your body’s needs and respiratory patterns. Heart rate variability typically decreases as you get older.

Your heart’s primary responsibility is to react to changes in your life and surroundings regardless of you’re feeling — awake, asleep, calm, or stressed. However, it relies on another body’s system because it doesn’t know how to react independently. 

Parasympathetic vs. Sympathetic Branches

Your brain and nervous system support your heart’s functionality. Your senses feed information to your brain, which has a direct line to your heart, the autonomic nervous system. This set of nerves in your brain operates without knowing it and informs your heart when it needs to speed up and work harder. The autonomic nervous system is divided into two parts.

Sympathetic

Your fight-or-flight response stems from this system and manages heart rate and blood pressure increases during emergencies. 

Parasympathetic

The parasympathetic nervous system balances the sympathetic nervous system and controls the natural relaxation response. Additionally, it slows your heart rate and blood pressure, especially during resting HRV or when you’re taking it easy.

The autonomic nervous system can become impaired in some cases, causing autonomic dysfunction. Autonomic dysfunction develops when the nerves of this system get damaged, and this condition can range from mild to life-threatening. Some issues resulting from autonomic dysfunction are temporary and reversible, while others are chronic and long-term, worsening over time. 

Research on HRV and PTSD 

Between July 14, 2008, and May 24, 2012, active-duty Marines were assessed 1 to 2 months before a combat deployment and again 4 to 6 months after their return. After accounting for deployment-related combat exposure, lower HRV before deployment as an increased low frequency to a high-frequency ratio of HRV was associated with the risk of PTSD diagnosis post-deployment.

Those who are more susceptible to anxiety and have a decreased resilience to stress are at an at-risk state for developing stress disorders like PTSD. If these findings are replicated, interventions that change autonomic nervous system function may open novel opportunities for the prevention and treatment of PTSD.

The Association Between HRV and PTSD

Research shows a strong HRV PTSD connection with an average PTSD heart rate of 95.1 beats per minute. Individuals with PTSD showed lower levels of resting HRVcompared to those exposed to trauma without PTSD. Research also shows that individuals with PTSD also exhibited lower levels of mediated resting HRV than those with panic disorder, another anxiety disorder associated with lower resting HRV. Additionally, individuals with PTSD showed lower levels of HRV even after experiencing traumatic brain injury and levels of depression. 

This data makes it difficult to determine whether lower levels of HRV in individuals with PTSD  result from trauma vulnerability or exposure to trauma. However, since these reduced levels of HRV remain stable over time, they likely precede the onset of a traumatic event. Additional research suggests that HRV measured after exposure to trauma predicted the development of PTSD six months later. 

Individuals with reduced mediated resting HRV are more likely to develop PTSD and show more severe symptoms than those with higher mediated resting HRV. This data further supports the idea that low resting HRV increases an individual’s chances of developing PTSD. This susceptibility may be due to cognitive control processes.

Meadows Behavioral Healthcare works to regulate HRV in our Brain Center

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