Insulin Resistance, Biological Markers of PTSD Increased in Military Veterans

Military veterans with post-traumatic stress disorder (PTSD) are more likely to have increased insulin resistance and elevated biological factors related to PTSD, according to research published in Psychoneuroendocrinology.

Esther M. Blessing, MD, PhD, of the Steven and Alexandra Cohen Veterans Center for Posttraumatic Stress and Traumatic Brain Injury, department of psychiatry at New York University Langone Medical Center, and colleagues, conducted a case-control study to examine markers of cardiometabolic disease — including insulin resistance, metabolic syndrome, and insulin resistance — in US Armed Forces veterans with PTSD.

Study participants were recruited from regional Veterans Affairs Medical Centers; Mental Health Services of the Manhattan, Bronx, and Brooklyn Veterans Affairs Medical Centers; and reservist agencies, among others. The study included 83 veterans with PTSD (current, war zone-related PTSD of at least 3 months duration) and 83 controls age matched 1:1.

In participants with PTSD, average symptom severity, determined via Clinician Administered PTSD Scale (CAPS) score was 69.7, considered “severe” (CAPS 60-79); symptom severity ranged from 44 (moderate) to 113 (extreme), and all controls were asymptomatic. Average PTSD duration was 5.7 years and average time since worst PTSD event was 5.9 years. On average, participants with PTSD smoked more frequently, had significantly lower education levels, and had a slightly, but still significantly, higher body mass index (BMI). In the PTSD group, 46 participants had comorbid major depressive disorder (MDD) compared with 1 participant in the control group. Overall, BMI in both groups was within the overweight range (25 to 29.9 kg/m²).

Examined via homeostatic model assessment (HOMA), insulin resistance was “significantly higher” in participants with PTSD vs controls, including elevated fasting glucose and fasting insulin; these levels were high following assessment of smoking status or antidepressant use as covariates (P <.01). Participants with PTSD also had a significantly higher frequency of metabolic syndrome (21.3% vs 1.3%; P <.005), with no difference in hemoglobin A1c (HbA1c) between groups.

In participants with metabolic syndrome, insulin resistance was well within the “severe” range and was BMI >30 kg/m². Of those participants, 29% also had elevated triglycerides, 34% had decreased high-density lipoprotein (HDL)-cholesterol, and 30% had increased waist circumference. Of participants with PTSD, 20% were also diagnosed with prediabetes vs 18.8% of controls.

Dr Blessing and colleagues also set out to examine whether the biological features mediating cardiovascular risk in PTSD correlated with PTSD-related insulin resistance. The investigators found that participants with PTSD had significantly higher levels of brain-derived neurotrophic factor, heart rate, C-reactive protein, tumor necrosis factor-α, and interleukin-6 levels vs controls. Plasma cortisol was similar between groups, but other predictors indicated a weak or no correlation. Similar correlations were noted in controls but were less pronounced.

“Our results add to previous findings associating PTSD with impaired insulin function,” wrote Dr Blessing and colleagues. “The relatively more severe insulin resistance associated with PTSD in the current study may relate to [participants’] military veteran status, to the overall higher BMI … or their greater PTSD symptom severity.”

Dr Blessing and colleagues also noted that their findings support a “growing body of evidence” indicating that PTSD should be viewed as more than just a mental illness, as symptoms have an impact on multiple bodily systems.

“Results strongly support further research into early targeted screening strategies for preventing cardiometabolic risk associated with PTSD,” the researchers concluded. “Further study of how these somatic concomitants integrate with pathophysiology underlying PTSD symptoms may result in targeted treatment of this important comorbidity of PTSD.”

Study Limitations

• This study did not include women; conclusions are limited to men
•  Participants with PTSD had lower education status, possibly reflecting overall lower socioeconomic status, which has previously been linked to dietary factors that increase type 2 diabetes risk
• Diet or exercise habits of participants were not assessed
•  A small number of subjects presented with HbA1c levels within the type 2 diabetes range and may have represented undiagnosed type 2 diabetes
• Only a limited set of biological variables that potentially link PTSD with increased insulin resistance were studied

Reference

Blessing EM, Reus V, Mellon SH, et al. Biological predictors of insulin resistance associated with posttraumatic stress disorder in young military veterans. Psychoneuroendocrinology. 2017;82:91-97. doi:10.1016/j.psyneuen.2017.04.016