Trauma and the Body: The Role of the Autonomic Nervous System

Psychiatric disorders related to exposure to psychological trauma represent a major public health concern due to their high prevalence and substantial societal burden. Post-traumatic stress disorder (PTSD), in particular, affects a considerable proportion of the population, with prevalence rates varying according to the nature and chronicity of exposure, as well as individual factors such as age, sex/gender, socioeconomic and socio-political context (Olff et al., 2025). For example, among military members and veterans, estimates suggest that rates may reach up to 20% (Institute of Medicine, 2014), while the estimated global lifetime prevalence is 3.9% (Koenen et al., 2017, as cited in Göçen et al., 2024). Importantly, the impact of trauma extends beyond PTSD. As highlighted by the meta-analysis by Hogg et al. (2022), psychological trauma exposure is associated with nearly a threefold increased risk of developing a mental health disorder, including Major Depressive Disorder (MDD), Bipolar Disorder (BD), anxiety disorders, dissociative symptoms, Substance Use Disorders (SUD), Obsessive-Compulsive Disorders (OCD) and sleep disorders, underscoring the broad and transdiagnostic impact of traumatic experiences (Figure 1) (Hogg et al., 2022; Olff et al., 2025). This highlights the need to better understand the mechanisms linking trauma exposure to such a wide range of outcomes. This raises an important question: why is psychological trauma associated with the development of such a wide range of mental disorders? The present thesis addresses this issue by focusing on a potential transdiagnostic mechanism, namely Autonomic Nervous System (ANS) dysregulation.