Posttraumatic stress disorder (PTSD) is a debilitating condition characterized by post-traumatic stress symptoms (PTSS) that persist for more than one month after trauma (Calhoun et al., 2012; Jorge, 2015). About 7% of Americans suffer from PTSD at some point in their lives; consequently, PTSD is considered to have a major impact on public health (Kessler and Wang, 2008). The factors and brain changes that contribute to PTSD development after an adult traumatic event remain largely unknown.

Relationships between PTSS and organization of brain structure have been a focus of previous work (Bremner, 2006; Xie et al., 2018). The thalamus is a large diencephalic structure composed of heterogeneous nuclei that contribute to diverse functions including sensation, cognition, memory, and fear processing (Beas et al., 2018; Bergmann, 2008; LeDoux, 1986; Penzo et al., 2015; Steriade and Llinás, 1988). In general, alterations in the thalamus have been linked to a range of stress-related processing changes, including incorrect integration of trauma-related sensory inputs (Brewin, 2001), inappropriate attention processing (Suvak and Barrett, 2011), and over-consolidation of traumatic memory (Brewin, 2001; Suvak and Barrett, 2011).

PTSS have been shown to be associated with functional changes in the thalamus (Yan et al., 2013; Yin et al., 2011). In addition, thalamic structural alterations have been reported in chronic PTSD patients. One sMRI study has reported gray matter atrophy in the thalamus was significantly greater in chronic PTSD patients than controls (Cardenas et al., 2011). Trauma-related re-experiencing symptoms also negatively correlated with thalamus volumes in chronic PTSD patients (Shucard et al., 2012). The above findings on thalamic structure focus on chronic effects years after trauma. However, PTSS can emerge immediately after trauma and brain structural effects can be seen during the early post-trauma period. For example, we previously reported that hippocampal volumes are negatively associated with PTSS from 2 weeks to subsequent months after trauma in survivors who develop PTSD (Xie et al., 2018). Potential thalamic structural contributions to early PTSS and PTSD development after acute trauma have received little attention. Interestingly, one recent study reported that whole thalamus gray matter volume interacted with fear-potentiated startle at 2 weeks post trauma to predict PCL score 8 weeks later (Steuber et al., 2021). How these results relate to early post-trauma PTSS severity remains unknown. Recent neuroimaging studies also suggest thalamic nuclei volume changes are related to mental and neurological disorders including psychosis, obsessive-compulsive disorder (OCD), migraine, and epilepsy (Chen et al., 2021; Huang et al., 2020; Shin et al., 2019; Weeland et al., 2021). To our knowledge, no studies have assessed thalamic nuclei volume relationships to early post-trauma PTSS or PTSD development.

It has been suggested that adverse childhood experiences (ACEs) may affect development of brain structure which, in turn, may increase risk for PTSD after adult trauma. ACEs, which affect 7–60% of children, include neglect and physical, emotional, or sexual abuse (Gilbert et al., 2009). ACEs have been linked to mental health problems, including PTSD, later in life (Brewin et al., 2000; Kessler et al., 2010; McLaughlin et al., 2012; Nemeroff, 2016). For example, 17–23% of young adults who experienced at least one type of ACE were diagnosed with PTSD after trauma exposure later in adult life as compared to 10% of those without an ACE history (Widom, 1999).

Structural changes in a range of cortical and subcortical structures including prefrontal cortex, hippocampus, and amygdala have been reported in chronic PTSD patients with an ACE history (Bremner et al., 1997; De Bellis et al., 2002; Evans et al., 2016; Hart and Rubia, 2012). Few studies have focused on diencephalic structures, including the thalamus. Children exposed to ACEs may have smaller thalamic volumes than children not exposed to ACEs (Hanson et al., 2010). ACE effects on stress systems have been proposed to underlie brain changes, impairment of stress responses, and vulnerability to PTSD (De Bellis and Zisk, 2014). Whether or how ACEs influence thalamic volumes, stress responses, and PTSD development in related ways at early times after adult trauma is unknown.

To investigate the potential associations between ACEs, subsequent early post-trauma whole thalamus and thalamic nuclei volumes, and PTSS and PTSD development, the present study tracked self-reported ACEs, and whole thalamus and thalamic nuclei volumes at 2 weeks, PTSS at 2 weeks and 3 months, and PTSD diagnosis at 3 months after an adult trauma. This provided original temporal analyses of potential linkages between early life ACEs, subsequent early post-trauma thalamic volumes, and PTSS and PTSD development.