Decreased uncinate fasciculus tract integrity in male

Abstract

IntroductionApproximately 10% of trauma-exposed individuals have posttraumatic stress disorder (PTSD), 1 characterized by intrusions and avoidance of reminders of the traumatic event, altered cognitions and mood, and hyperarousal.2 The prevailing neurocircuitry model of PTSD postulates amygdala hyperactivity and ventromedial prefrontal cortex (vmPFC) hypoactivity.3,4 The amygdala plays a pivotal role in fear expression and salience processing, 5 whereas the vmPFC is important in top-down control over the fear response.6 Additionally, decreased resting-state functional connectivity between the amygdala and vmPFC has been observed in male patients with PTSD, possibly underlying diminished top-down prefrontal control over the fear response. White matter fibres, which make up more than 40% of total brain volume, 8 allow effective communication between (cortical and subcortical) brain areas. White matter integrity can be investigated noninvasively with diffusion tensor imaging (DTI), which measures the direction and coherence of water diffusion within myelinated and nonmyelinated tissue. 9 The DTI metrics fractional anisotropy (FA) and mean diffusivity (MD) are predominantly used to quantify white matter integrity: FA reflects the extent to which water diffusion is directionally restricted and represents axonal density and coherence, whereas MD (i.e., magnitude of overall diffusion) is sensitive (but not specific) to membrane integrity. 10,11 In line with the prevailing neurocircuitry model of PTSD, lower white matter integrity of tracts connecting the prefrontal cortex with limbic regions, including the cingulum bundle and uncinate fasciculus, has been associated with PTSD and its development. 12-14 The uncinate fasciculus connects the orbital, medial and lateral prefrontal cortex with rostral temporal areas, including the anterior temporal lobe, parahippocampal Background: Posttraumatic stress disorder (PTSD) is a disabling psychiatric disorder that has been associated with lower white matter integrity of tracts connecting the prefrontal cortex with limbic regions. However, previous diffusion tensor imaging (DTI) findings have been inconsistent, showing high variability in the exact location and direction of effects. Methods: We performed probabilistic tractography of the bilateral uncinate fasciculus, cingulum and superior longitudinal fasciculus (both temporal and parietal projections) in male and female police officers with and without PTSD. Results: We included 38 (21 men) police officers with and 39 (20 men) without PTSD in our analyses. Compared with trauma-exposed controls, patients with PTSD showed significantly higher mean diffusivity of the right uncinate fasciculus, the major white matter tract connecting the amygdala to the prefrontal cortex (p = 0.012). No other significant between-group or group × sex differences were observed. Mean diffusivity of the right uncinate fasciculus was positively associated with anxiety symptoms (r = 0.410, p = 0.013) in patients with PTSD as well as with amygdala activi...

Multimodal structural neuroimaging markers of risk and recovery from posttrauma anhedonia: A prospective investigation

“…By pooling data across scanners, we further demonstrated the robustness of the predictive utility of uncinate fasciculus FA for longterm PTA with respect to both acquisition and processing method from the present sample. Several reports have found uncinate fasciculus microstructure to vary with traditional PTSD symptom clusters (Costanzo et al, 2016;Harnett, Ference et al, 2020;Koch et al, 2017;Olson et al, 2017;Santhanam et al, 2019), although to date only one prior study has investigated its role in PTA symptoms (Fani et al, 2019). Further, few studies have utilized a longitudinal design to identify whether white matter microstructure assessed acutely post-trauma is predictive of future PTSD symptoms.…”

“…Importantly Prior work has demonstrated that PTSD is associated with alterations in white matter pathways that interconnect neural circuitry critical for fear-and reward-related processes that are dysfunctional in PTSD (Fenster et al, 2018;Harnett, Goodman et al, 2020). Specifically, fractional anisotropy (FA) of the uncinate fasciculus (amygdala to ventromedial prefrontal cortex [PFC]) and cingulum bundle (PFC to posterior cingulate and hippocampus) is reduced in individuals with PTSD compared to non-PTSD controls (Costanzo et al, 2016;Fani et al, 2016;Koch et al, 2017;Olson et al, 2017;Sanjuan et al, 2013). In addition, the fornix (which connects the hippocampus to deep-brain nuclei), may also be involved in PTSD; prior research has demonstrated increased fornix and stria terminalis FA over time within treatment-resistant PTSD patients (Kennis et al, 2015) and fornix FA has been found to be positively related to trait anxiety (Modi et al, 2013).…”

Disrupted Amygdala Connectivity Is Associated With Elevated Anxiety in Sensorineural Hearing Loss

“…As shown in Figure 3 , the shape and trajectory of the UF are highly consistent with the template (Yeh, 2020 ) and previous literature (Maier-Hein et al, 2017 ; Park et al, 2019 ; Sanvito et al, 2020 ). The UF is the major white matter tract connecting the ventral pre-frontal cortex and the amygdala (Koch et al, 2017 ), which takes a crucial part of the bidirectional communication within the amygdala-vPFC circuit. However, it is unclear how the structural connectivity of the UF relates to amygdala related emotional impairments.…”

Current and future functional imaging techniques for post-traumatic stress disorder

“…Other studies did not observe differences in the CAB, but instead showed WMT changes in uncinate fasciculus, a white matter tract connecting the AMY to the vmPFC, a decit possibly underlying reduced inhibitory control over the fear response. 78 Other investigators have taken a networking approach and reported distinct differences in the white matter tracts of the salience network between PTSD and control participants. 67,79 Overall, these studies are preliminary and few current literature reviews or metanalyses on this topic are available.…”