Exaggerated anxiety is not unique to CO2 in panic disorder: a comparison of hypercapnic and hypoxic challenges.

Current biological models of panic disorder (PD) assert that this disorder is maintained by hypersensitivity to carbon dioxide (CO2) and related asphyxia cues, which is manifested as an exaggerated suffocation alarm (D. Klein, 1993). Because suffocation can result from both increased CO2 (hypercapnia) and decreased oxygen (O2; hypoxia), this study examined respiratory responding and anxiety during 5% CO2 (a hypercapnic challenge) and 12% O2 (a hypoxic challenge) in 14 PD patients and 14 matched controls (MC). Results demonstrate that irrespective of the source of suffocation, PD patients respond with increased anxiety relative to MC participants. Significant group differences were observed in respiratory functioning, with the PD patients showing higher respiratory rates in response to both challenges. The MC sample demonstrated the expected respiratory responses to both hypercapnia and hypoxia. The findings indicate that PD patients are hypersensitive to alterations in breathing and that this reactivity is not specific to CO2.     

Attentional interference by threat and post-traumatic stress disorder: The role of thought control strategies

Attentional interference by threat is associated with PTSD, but the mechanisms of this relationship remain unclear. Attentional interference might be related to increased use of maladaptive thought control strategies, such as suppressing unwanted thoughts (thought suppression) or replacing threatening thoughts with everyday concerns (worry), which increase PTSD risk. Conversely, attentional interference might be associated with reduced use of adaptive strategies, such as talking about threatening thoughts (social control), which decrease PTSD risk. This study tested if thought control strategies mediate the relationship between attentional interference and PTSD. Sixty-one male Vietnam-era veterans completed measures of PTSD symptoms and thought control strategies. Participants also completed a Visual Search Task measuring attentional interference, which required participants to identify a target letter string among a group of threat or neutral words. Attentional interference by threat was related to PTSD symptoms, and mediation analyses revealed significant indirect effects of attentional interference through thought suppression and worry. Attentional interference was related to re-experiencing and avoidance, but not hyperarousal, symptom clusters. Thought suppression was a unique mediator for re-experiencing, whereas thought suppression and worry both mediated the relationship with avoidance. These results offer evidence for maladaptive thought control strategies as a mechanism linking attentional biases for threat to PTSD.     

Humean dispositionalism

Humean metaphysics is characterized by a rejection of necessary connections between distinct existences. Dispositionalists claim that there are basic causal powers. The existence of such properties is widely held to be incompatible with the Humean rejection of necessary connections. In this paper I present a novel theory of causal powers that vindicates the dispositionalist claim that causal powers are basic, without embracing brute necessary connections. The key assumptions of the theory are that there are natural types of causal processes, and that manifestations of powers are identified with certain kinds of causal processes. From these assumptions, the modal features of powers are explained in terms of internal relations between powers themselves and the process-types in which powers are manifested.     

Training Experiences as Mediators of the Association Between Gender-Role Egalitarianism and Women��s Adjustment to Marine Recruit Training

Women may face particular challenges adjusting to the military environment, in part due to their numerical minority status in a traditionally male culture. In addition, women are more likely than men to experience the added stressor of sexual harassment. We examined several potential mediators of the relationship between gender-role egalitarianism and adjustment to boot camp training in a sample of 658 female U.S. Marine recruits. Results indicated that sexual harassment, performance stress, and unit cohesion mediated the relationship between egalitarianism and mental health symptomatology. These findings suggest that beliefs about gender roles are important to consider in efforts to improve women??s adjustment in the military.     

The role of attentional biases in PTSD: is it interference or facilitation?

Although attentional biases have been demonstrated in individuals with posttraumatic stress disorder (PTSD), the cognitive methodologies used have not allowed for disambiguation of two types of attentional biases. It remains unclear if PTSD involves difficulty disengaging attention from threatening stimuli (interference) or facilitated detection. To differentiate between attentional interference and facilitation, 57 male Vietnam-era veterans (30 High PTSD and 27 Low PTSD) completed a visual search task with a lexical decision component. High PTSD veterans who engaged in the interference task first showed increased interference to threat-relevant words relative to Low PTSD veterans. However, no evidence was found for facilitated detection of threatening stimuli in PTSD.     

Response patterns to repeated CO2 inhalation in individuals with high anxiety sensitivity.

The present report extends previous work which has documented two distinct response patterns to repeated presentation of interoceptive cues (using CO2 inhalation) in PD patients [Beck, J. G. & Shipherd, J. C. (1997). Repeated exposure to interoceptive cues: does habituation of fear occur in panic disorder patients? Behaviour Research and Therapy, 35, 551-557]. We were interested in determining if these two patterns of fear habituation and sensitization would be noted in panic-naive individuals who reported high levels of Anxiety Sensitivity. A second aspect of this report examined whether attention to bodily sensations versus to neutral material would impact fear habituation and sensitization. Participants included 43 panic-naive individuals who scored at least 1 standard deviation above norms on the Anxiety Sensitivity Index. Results indicated that 37% of the sample reported habituation of fear, 47% reported fear sensitization and 16% demonstrated relatively stable fear levels across 12 inhalations of CO2 during session 1. The attentional manipulation did not exert a pronounced influence on anxiety, panic symptom severity, skin conductance, or heart rate in either Habituators or Sensitizers during session 2. These results are discussed in light of their relevance in understanding fundamental psychopathological processes underlying Panic Disorder.     

Main and interactive effects of social support in predicting mental health symptoms in men and women following military stressor exposure

Abstract

Evidence across a multitude of contexts indicates that social support is associated with reduced risk for mental health symptoms. More information is needed on the effectiveness of different sources of support, as well as sex differences in support. Associations between social support from two sources – the military unit and friends and family – and mental health symptoms were examined in a study of 1571 Marine recruits assessed at the beginning and end of a highly stressful 13-week training program. Military social support buffered the stressor exposure–posttraumatic stress symptomatology (PTSS) relationship, whereas the relationship between stressor exposure and PTSS was highest when civilian social support was high. Further inspection of the interactions revealed that military support was most important at high levels of stressor exposure. Sex differences in the relationship between social support and symptoms were found, such that support from military peers was associated with lower levels of PTSS for men, whereas civilian support was associated with lower PTSS for women. While civilian social support was associated with lower levels of depression symptom severity in both women and men, the relationship was stronger for women. Reviewed implications focus on the importance of considering the recipient, source, and context of social support.