Recovery from Posttraumatic Stress Requires Dynamic and Sequential Shifts in Amygdalar Connectivities

Abstract

The neural mechanisms underlying the development and maintenance of posttraumatic stress disorder (PTSD) have long been studied. However, little is known about the neural correlates of the recovery process from PTSD. A 5-year longitudinal study was conducted to investigate the trajectory of structural connectivities of the amygdala in disaster survivors with PTSD. Thirty disaster survivors, who were diagnosed with PTSD, and 29 healthy individuals, who were not exposed to trauma, underwent three waves of assessments including neuroimaging scanning over a 5-year period from the time of the disaster at approximately 1.3-year intervals. All disaster survivors showed significant improvements in PTSD symptoms over time. Using diffusion tensor imaging analysis, a 5-year trajectory of amygdalar structural connectivities with key brain regions was assessed. The amygdala-insula connection was initially strengthened and then normalized during recovery, while the amygdala-prefrontal cortex (PFC) connection was at first unaffected, then strengthened, and eventually normalized. The lower tract strength of the amygdala-thalamus connection normalized during recovery, while that of amygdala-hippocampus connection remained low. The greater amygdala-PFC connectivity was associated with less PTSD symptom severity. The present longitudinal study revealed that recovery from PTSD parallels dynamic and sequential shifts in amygdalar connectivities with multiple brain regions, suggesting the expanded view of fear circuitry including the insula and thalamus, beyond the traditional model which primarily involves the amygdala, PFC, and hippocampus.

Neurobiology of comorbid post‐traumatic stress disorder and alcohol‐use disorder

“…Non‐diagnosed trauma‐exposed children and adolescents fail to engage inhibitory circuits between the pre‐genual cingulate cortex and amygdala during regulation of emotional conflict (Marusak et al ). In agreement with this observation, high PFC–amygdala connectivity is associated with lower PTSD symptom severity in disaster survivors diagnosed with PTSD (Yoon et al ). Another study showed that certain risk allele carriers diagnosed with PTSD exhibit white matter deficits in the uncinate fasciculus, which serves as a primary connection between ventral PFC and amygdala, suggesting gene × trauma interaction effects on long‐term brain structure and function (Almli et al ).…”

Acute and long-lasting effects of oxytocin in cortico-limbic circuits: consequences for fear recall and extinction

“…Additionally, some structural and functional deficits in this area have been found in fMRI studies in neuropsychiatric disorders, such as generalized anxiety disorder (Andreescu et al 2017) and PTSD (Shvil et al 2014), which both affect severely the extinction of fear memories. In the case of PTSD, interestingly, the activation of ACC, together with the vmPFC and hippocampus, is sexually dimorphic: men with PTSD exhibited increased activation in the left rostral dACC during extinction recall compared to women with PTSD (Shvil et al 2014;Yoon et al 2017). Further, animal and human studies (Cullen et al 2015;Levar et al 2017aLevar et al , 2017b have positioned the ACC as an important hub to trigger fear retrieval alongside the PL, and its inhibition might be a way to boost fear extinction.…”

Diagnostic potential of multimodal neuroimaging in posttraumatic stress disorder

“…The trauma-exposed group in this study included survivors of a subway fire disaster in South Korea [ 9 , 10 ]. The initial assessment was conducted for 38 individuals aged 18 to 50 years at approximately 1.65±0.74 months after the disaster (time 0).…”

“…In our previous studies on the survivors of a subway fire disaster, we found that increased cortical thickness in the dorsolateral prefrontal cortex [ 9 ] and elevated structural connectivity between the amygdala and orbitofrontal and ventromedial prefrontal cortex (OMPFC) [ 10 ] were related to PTSD symptom improvement, and such involvement of specific brain structural features could dynamically change during recovery from PTSD. These findings seem to provide important implications for the use of potential neuroanatomical markers in diagnosing PTSD and predicting recovery from PTSD.…”