**2. The relationship between PTSD and anger**

Anger is strongly associated with other dysphoric and aversive emotions. When dysfunctional it is closely associated with psychiatric conditions. Research shows that individuals with anxiety disorders experience greater anger severity, aggression, hostility and anger-related impairment, compared to those without them [9]. Anger is also often prominent in chronic pain conditions (particularly complex regional pain syndromes and fibromyalgia) [36] and psychotic spectrum disorders [9]. It is further associated with personality disorders, especially borderline, narcissistic, paranoid and antisocial types [37].

Anger's strongest link is, however, with PTSD. Sufferers of PTSD experience greater anger compared to individuals with subthreshold PTSD [38] and those without it [9]. They also have greater difficulty with anger control, compared to individuals suffering social or generalised anxiety or panic and obsessive-compulsive disorders [9, 39]. This has been identified in clinical samples like combat veterans [24] and non-clinical student samples [38].

The anger-PTSD association reflects several influences. Initially, there is the effect of anger's base-rate prevalence. Although it is not well understood clinically, anger, along with anxiety and depression, forms the "big three" [40], "unholy trinity" or "FAD" (fear-anger-depression) [41] of negative affect, but is considered the predominant emotion in treatment contexts [42]. Moreover, negative affects rarely occur alone. Typically, they share a content overlap and are recursively interdependent in their dysphoric effects. Consequently, beyond the direct impact of its high base-rate, anger also has a significant indirect association with PTSD through its strong relationship with other primary emotions [43].

Anger is more intertwined with other negative affects than any other emotion and comorbid aversive emotions are the norm in PTSD. Prominent, high impact emotions in PTSD that share an intimate relationship with anger include horror and disgust [44] and "responsibility emotions", such as guilt and shame [45, 46]. Shame-proneness is thought to be related to anger arousal, resentment and irritability and associated with indirect/non-expression of anger [47]. The angriest people have strong underlying feelings of guilt and shame [48]. Tournier observed that "Irritation-aggressiveness: this is the law of unconscious and repressed guilt [… and …] those affected by guilt may be understandably irritable and at times, explode in anger or rage" (page 150) [49].

Considered one of the "moral emotions" [50], anger is a response to perceived failure to meet responsibility [51] and social norms [52] and is concerned with norm enforcement [53]. Exposure to potentially traumatising events (PTEs), and particularly extreme and malevolent interpersonal PTEs, almost inevitably raises issues of causality and intense meaning-related issues around responsibility and failure by commission or omission. This is provided for in hypothetical constructs that seek to explain trauma-related responses associated with anger. For example, the core symptoms of posttraumatic embitterment disorder [54] include: negativity, helplessness, blame of self and others, non-specific somatic symptoms, phobic avoidance of persons or situations related to the PTE, intrusions, phantasies of revenge and aggression. Additionally, in betrayal-based moral injury [55], anger is directed at another person who is perceived as having perpetrated a betrayal resulting in the injury or worse of associates.

Importantly, it is the relationship anger has with PTSD that is critical. This was highlighted almost 30 years ago by Lasko, Gervis, Kuhne, Orr and Pitman [56], who observed "increased aggression in war veterans is more appropriately regarded as a property of PTSD, rather than a direct consequence of military combat" (page 373). That observation was elaborated upon in the first meta-analysis undertaken in relation to anger and PTSD by Orth & Wieland in 2006. They concluded that "anger and hostility are substantially related to PTSD among samples who have experienced all possible types of traumatic events, not only in individuals with combat-related PTSD" (page 704) [57].
