TMAO (trimethylamine n-oxide) as a potential biomarker of individual severe stress perception in posttraumatic stress disorder (PTSD)-vulnerable patients after acute myocardial infarction

Abstract Background Acute myocardial infarction is not only a somatic disease but potentially triggers psychological effects, too. Post-traumatic stress disorder (PTSD) is a common stress-related disorder. It is characterized by numerous symptoms, such as flashbacks, intrusions, nightmares and severe anxiety, as well as uncontrollable, intense and disturbing thoughts and feelings related to the traumatic experience. However, with regard to the development of PTSD, individual stress perception might be crucial since not every serious traumatic experience leads to PTSD. To date, almost no biological correlates of an individual's perception of stress have been identified as being associated with the long-term development of PTSD. Objective The aim of the study was to determine whether blood levels of TMAO vary immediately after AMI (1) in patients with or without depression, and (2) in patients with AMI induced PTSD symptomatology (subsyndromal PTSD and full PTSD). Furthermore, we investigated whether TMAO is a potential biomarker that might be useful in the prediction of PTSD symptomatology in the long term. Method A total of 114 AMI patients were assessed with standardized clinical psychiatric interviews based on the Hamilton Depression Scale (HAMD-17) after admission to the hospital and 6 months later. In addition, the CAPS-5 was used to explore PTSD symptoms (subsyndromal PTSD and full PTSD) 6 months after AMI. To assess patients' TMAO status, serum samples were collected at hospitalization and 6 months after AMI. Results Study participants with post-myocardial infarction PTSD symptomatology (subsyndromal PTSD and full PTSD) had significantly higher TMAO levels immediately after AMI than patients without PTSD symptoms (ANCOVA: TMAO (PTSD x time), F = 4.544, df = 1, p=0.035). In contrast, depressive symptomatology 6 months after AMI had no influence on TMAO levels (TMAO (depression x time), F = 0.083, df = 1, p=0.774). With the inclusion of additional clinical predictors in a hierarchical logistic regression model, TMAO becomes a significant predictor of PTSD symptomatology. Conclusions An elevated TMAO level immediately after AMI might reflect severe stress in PTSD-vulnerable patients, which might also lead to a short-term increased gut permeability to trimethylamine (TMA), the precursor of TMAO. Thus, elevated TMAO might be a biological correlate for stress that is associated with vulnerability to PTSD and might help to identify patients at increased risk. Funding Acknowledgement Type of funding sources: None.