The Association Between Post-Traumatic Stress Disorder (PTSD) and Heart Disease

Post by Leanna Kalinowski 

The takeaway

There is an increased risk of heart disease among individuals with PTSD. This risk strengthens following chronic PTSD and is attributable to impaired microvascular function.

What's the science?

The human body is designed to rapidly respond to threats and stressful situations by activating the sympathetic nervous system during the stress response. This leads to an increase in cardiovascular activity, helping one to fight or flee from a stressful stimulus. This is a normal physiological response; however, it can become dysregulated in disorders such as posttraumatic stress disorder (PTSD), which is a chronic psychiatric disorder that develops in some individuals who have experienced a traumatic event. When individuals with PTSD experience a reminder of their trauma, such as a loud noise, their sympathetic nervous system is activated despite the lack of an active threat. This repeated activation is believed to cause an increased risk of heart disease among individuals with PTSD, perhaps through repeated bouts of inflammation and vascular “wear and tear”. However, the exact mechanisms underlying this risk have not been demonstrated. This week in Biological Psychiatry, Vaccarino and colleagues conducted a longitudinal twin study with war veterans to determine the mechanisms underlying the association between PTSD and heart disease.

How did they do it?

A group of 275 twins was selected from the Vietnam Era Twin Registry, which is a large national sample of adult male twins who served on active duty during the Vietnam war era. Studying twins allows for the researchers to separate out factors that are often associated with both PTSD and heart disease but do not causally link the two disorders, including genetic and environmental factors that run in families and are shared among twins. Participants each underwent two examinations that were twelve years apart, each of which included a clinical assessment of PTSD. Participants were classified into one of three groups: no history of PTSD, late-onset PTSD (i.e., not diagnosed at visit 1 but diagnosed at visit 2), and longstanding PTSD (i.e., diagnosed at both visits).

Participants also underwent myocardial perfusion at both examinations, which is a positron emission tomography (PET) imaging test that shows how well blood flows through the heart muscle. PET scans of the heart were taken before and after administration of adenosine, which is a drug that increases the workload of the heart to uncover subclinical disease. From these scans, the researchers were first able to determine whether participants lacked blood flow to the heart because of obstructive coronary artery disease, which is when plaque accumulation leads to a narrowing or blockage of the large arteries that supply blood to the heart. They were also able to assess myocardial flow reserve, which is a measure of the health of the small coronary vessels that bring blood to the heart. Unlike obstructive coronary artery disease, coronary microvascular dysfunction is caused by damage to blood vessels rather than blockage by plaque. 

What did they find?

The researchers found that PTSD is associated with coronary microvascular dysfunction, indicated by lower myocardial flow reserve. This association was particularly noted among twins with longstanding PTSD. Twins with longstanding PTSD also experienced a lower myocardial flow reserve during their second visit compared to the first, suggesting a worsening of microvascular function following prolonged PTSD. These associations persisted even after comparing twin brothers with different PTSD trajectories, ruling out shared genetic and environmental factors, as well as when accounting for other psychiatric disorders, such as depression and substance abuse. Furthermore, there was no evidence that twins with PTSD had more obstructive coronary artery disease, suggesting that the association between PTSD and heart disease is due to damage to blood vessels rather than an increase in plaque accumulation.

What's the impact?

In summary, this unique study design allowed for the researchers to examine how heart disease progresses in relation to PTSD status and duration over a 12-year period. Their findings support a link between PTSD and heart disease and suggest that microvascular function is the mechanism underlying this association. Understanding this mechanism will help in long-term efforts for risk prediction, prevention, and treatment to reduce the burden of heart disease among individuals with PTSD. 

Vaccarino et al. Posttraumatic stress disorder, myocardial perfusion and myocardial blood flow: A longitudinal twin study. Biological Psychiatry (2021). Access the original scientific publication here.