Decreased Plasma Oxytocin Levels in Patients With PTSD

Claudia Carmassi; Donatella Marazziti; Federico Mucci; Alessandra Della Vecchia; Filippo Maria Barberi; Stefano Baroni; Gino Giannaccini; Lionella Palego; Gabriele Massimetti; Liliana Dell'Osso

doi:10.3389/fpsyg.2021.612338

Decreased Plasma Oxytocin Levels in Patients With PTSD

Front Psychol. 2021 Jul 1:12:612338. doi: 10.3389/fpsyg.2021.612338. eCollection 2021.

Authors

Affiliations

¹ Department of Clinical and Experimental Medicine, Section of Psychiatry, University of Pisa, Pisa, Italy.
² Unicamillus-Saint Camillus International University of Medical and Health Sciences, Rome, Italy.
³ Department of Biotechnology, Chemistry and Pharmacy, University of Siena, Siena, Italy.
⁴ Department of Psychiatry, North-Western Tuscany Region, NHS Local Health Unit, Viareggio, Italy.
⁵ Department of Pharmacy, University of Pisa, Pisa, Italy.

Abstract

Introduction: Although the pathophysiology of post-traumatic stress disorder (PTSD) is still unclear, growing preclinical evidences suggest that oxytocin (OT), a pleiotropic hormone, is possibly involved. However, direct studies on OT levels or clinical trials with this exogenous hormone in patients with PTSD led to inconsistent findings. Therefore, the aim of the present study was at exploring and comparing the plasma OT levels in a group of patients with PTSD and matched healthy subjects as the control group.

Materials and methods: Twenty-six outpatients (13 men, 13 women, mean age: 40.3 ± 11.5 years) suffering from PTSD, according to the Diagnostic and Statistical Manual for Mental Disorders, fifth edition (DSM-5), and 26 healthy subjects (13 men, 13 women, mean age: 43.8 ± 12.7 years) were included. The patients were assessed through the structured clinical interview for DSM-5 research version, patient edition (SCID-I/P), and the Impact for Event Scale revised (IES-R). All fasting subjects underwent three venous blood samples for the subsequent oxytocin radioimmunoassay. We used unpaired Student's t-test to assess OT levels and the intergroup difference of demographic characteristics, while anxiety, avoidance, and hyperarousal scores were compared among groups adjusting for the effect of gender and age by means of analysis of covariance (ANCOVA). The correlations between different variables were investigated by Pearson's method.

Results: The most common traumatic events of patients with PTSD were the following: severe car accident, physical violence, sexual violence, sudden death of a loved one, and natural disaster. The IES total score was 55 ± 15. Student's t-test revealed that the patients showed significantly lower OT levels (mean ± SD, pg/ml) than healthy control subjects (4.37 ± 1.61 vs 5.64 ± 2.17, p < 0.001). We detected no correlation between the IES total score, subscales, or single items and OT plasma levels. Again, no difference between men and women was detected in the patients' group, while healthy control women showed higher OT levels than men.

Discussion: Our study, while reporting the presence of decreased plasma OT levels in outpatients with PTSD of both sexes, as compared with healthy control subjects, would support the possible involvement of OT in the pathophysiology of PTSD. However, given the complexity of the clinical picture, future investigations are necessary to better deepen the role and level of OT in PTSD.

Keywords: PTSD; biomarkers; oxytocin; pathophysiology; stress system; therapeutic targets.