Neuroimaging Correlates of Resilience to Traumatic Events—A Comprehensive Review

Abstract

Improved understanding of the neurobiological correlates of resilience would be an important step toward recognizing individuals at risk of developing post-traumatic stress disorder (PTSD) or other trauma-related diseases, enabling both preventative measures and individually tailored therapeutic approaches. Studies on vulnerability factors allow drawing conclusions on resilience. Structural changes of cortical and subcortical structures, as well as alterations in functional connectivity and functional activity, have been demonstrated to occur in individuals with PTSD symptoms. Relevant areas of interest are hippocampus, amygdala, insula, anterior cingulate cortex, and prefrontal cortex, as well as related brain networks, such as the default-mode, salience, and central executive network. This review summarizes the existing literature and integrates findings from cross-sectional study designs with two-group designs (trauma exposed individuals with and without PTSD), three-group designs (with an additional group of unexposed, healthy controls), twin-studies and longitudinal studies. In terms of structural findings, decreased hippocampal volume in PTSD individuals might be either a vulnerability factor or a result of trauma exposure, or both. Reduced anterior cingulate cortex and prefrontal cortex volumes seem to be predisposing factors for increased vulnerability. Regarding functional connectivity, increased amygdala connectivity has been demonstrated selectively in PTSD individuals, as well as increased default-mode-network and salience network connectivity. In terms of functional activity, increased amygdala and anterior cingulate cortex activities, and decreased prefrontal cortex activity as a response to external stimuli have been associated with higher vulnerability. Increased prefrontal cortex activity seemed to be a protective factor. Selecting adequate study designs, optimizing the diagnostic criteria, as well as differentiating between types of trauma and accounting for other factors, such as gender-specific differences, would be well-served in future research. Conclusions on potential preventative measures, as well as clinical applications, can be drawn from the present literature, but more studies are needed.

The complex neurobiology of resilient functioning after childhood maltreatment

“…Two recent reviews of the neuroimaging literature suggest that resilient functioning in those with a history of CM (i.e. the absence of any mental health disorder as an outcome [44] or the absence of post-traumatic stress disorder [45]) has largely been examined only cross-sectionally and is related to altered volumes and/or function of (midline) PFC as well as to limbic regions and their functional connectivity [45][46][47]. For instance, in the multisite IMAGEN study (n = 1870 adolescents), larger right middle superior PFC volumes were shown to be associated with resilient functioning on multiple domains of functioning, including academic achievement, conduct, relationships and emotional health [48].…”

Potential Neurocognitive Biomarkers for Post Traumatic Stress Disorder (PTSD) Severity in Recent Trauma Survivors

“…To note that our classifier didn't identify several structural abnormalities found in previous cross-sectional studies of PTSD 7,25,34,38 . This includes the most replicated finding of small hippocampus 70 , but also abnormal volume of the amygdala, insular cortex, medial and dorsal prefrontal cortices (mPFC and dlPFC respectively) 28,31,33,[71][72][73] .…”

“…Another structural feature found to be of importance to the classification was the volume of the rostral anterior cingulate cortex (rACC), such that lower rACC volume was associated with higher PTSD severity. Indeed, rACC volume was previously associated with PTSD 34,67,68 . Importantly, it was also shown to predict cognitive behavioral treatment response for individuals with PTSD 69 , suggesting its potential as a guiding mechanism-based early intervention closely after trauma.…”

“…Accumulating neuroimaging evidence point to the presence of structural and functional brain abnormalities in PTSD patients 7,[25][26][27][28] , like lower hippocampal volume [29][30][31][32] and altered activity and connectivity of the amygdala, insula, ACC, mPFC and dlPFC; structures involved in threat detection, executive function, emotion regulation, and contextual processing 7,25,[33][34][35][36][37] . Importantly, some structural and functional neuroimaging studies also point to early predisposing factors to the development of PTSD 25,34,[38][39][40] . Despite promising finding from neurocognitive and neuroimaging studies these objective measures have not been integrated in a routine assessment or management of PTSD.…”

Neuroanatomical Risk Factors for Post Traumatic Stress Disorder (PTSD) in Recent Trauma Survivors

“…Furthermore, trauma exposure even in the absence of PTSD was shown to be associated with hippocampal volume decrease (17), and further hippocampal volume reduction was seen in chronic PTSD (18). Thus, it is yet to be clearly established whether reduced hippocampal size in PTSD is the result of trauma exposure, represents a risk factor for PTSD, or a combination of both (18,20,21). One possibility is that the hippocampus is not an isolated structural risk factor for PTSD, but that its pathological impact depends on the presence of additional brain anomaly.…”