Academic journal article European Journal of Psychotraumatology

The Impact of Cultural Differences in Self-Representation on the Neural Substrates of Posttraumatic Stress Disorder

Academic journal article European Journal of Psychotraumatology

The Impact of Cultural Differences in Self-Representation on the Neural Substrates of Posttraumatic Stress Disorder

Article excerpt

Research indicates that posttraumatic stress disorder (PTSD) is a universal phenomenon observed cross-culturally (Figueira et al., 2007; Foa, Keane, Friedman, & Cohen, 2009). However, it remains unknown as to whether the processes implicated in the development, maintenance, and treatment of PTSD are culturally similar. This limitation extends to our current understanding of the neural mechanisms underpinning PTSD. There is currently an impressive body of literature documenting the neural substrates of PTSD, yet there is very little empirical work investigating the impact of culture on these systems. The importance of considering cultural influences is strengthened by research emerging from the field of cultural neuroscience that clearly indicates culture modulates many of the same neural and psychological processes aberrant in PTSD. This review will first provide a focused overview of the current understanding regarding core neural mechanisms underpinning PTSD. Second, we will consider prominent cultural theories. Third, a summary of investigations into how culture modulates neural correlates relevant to the key processes affected in PTSD is presented. Finally, we will develop a model that can be used to guide future empirical work in the domain of PTSD.

Neurocircuitry underpinning five key disrupted mechanisms in PTSD

Across the spectrum of PTSD psychopathology, there are five key affective and cognitive functions that have been repeatedly identified as being disrupted in PTSD and have major relevance to conceptualising how culture may influence the neural substrates of PTSD. These are: (1) fear dysregulation; (2) attentional biases; (3) emotional memory impairments; (4) self-referential processing deficits; and (5) attachment and interpersonal processing alterations.

Fear dysregulation

PTSD is characterised by core disturbances in the neural balance between prefrontal regulatory systems over fear and arousal systems. The central neurocircuitry model of PTSD purports that hyperactivity within fear-processing networks (including the amygdala, insula, and hippocampus), coupled with reduced regulatory activity within medial prefrontal cortical (MPFC) regions and cognitive control centres (dorsolateral prefrontal cortex; DLPFC), results in an inability to control fear responses (see reviews by Hayes, Hayes, & Mikedis, 2012; Jovanovic & Ressler, 2010; Patel, Spreng, Shin, & Girad, 2012; Pitman et al., 2012; Shin & Liberzon, 2010). Functionally, disruptions to these neural systems in PTSD are reflected in a hypervigilance to threat (see 'Attention biases' section), compromised fear learning and extinction processes (Jovanovic & Ressler, 2010; Milad et al., 2009), and heightened stress sensitivity and poor regulation over strong negative emotional reactions (New et al., 2009). An alternative dysregulation model, whereby hyperactive medial prefrontal regions overmodulate fear networks, has also been proposed for a dissociative subtype of PTSD (Lanius et al., 2010). This neural pattern is associated with emotional withdrawal and numbing symptoms, deactivation of arousal systems, as well as depersonalisation and derealisation symptoms (Lanius, 2015; Lanius, Brand, Vermetten, Frewen, & Spiegel, 2012).

Aberrant fear extinction, perception, and regulation processes in PTSD may also be due to problems with contextual processing (Liberzon & Sripada, 2008). A striking feature of PTSD is that re-experiencing symptoms usually occur in a safe context, suggesting that those with PTSD have difficulty updating their contextual representations of the traumatic event (Hayes et al., 2011; Van Rooij, Geuze, Kennis, Rademaker, & Vink, 2015), as well as generalised context-processing deficits (Van Rooij et al., 2014). Dysregulation between MPFC and hippocampal networks, vital to healthy contextualisation of emotional events (Maren, Phan, & Liberzon, 2013), form the neural basis for poor extinction of fear memories in safe contexts in PTSD (Jovanovic, Kazama, Bachevalier, & Davis, 2012; Parsons & Ressler, 2013). …

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