| This research addressed three current controversies surrounding panic disorder (PD). One concerns its nosologic boundaries. Premenstrual dysphoric disorder (PMDD) and PD patients share elevated rates of challenge-induced panic, a commonality that a literature review revealed could not be accounted for by PMDD histories of PD or panic attacks. No physiologic hypothesis examined in this work emerged as an empirically supported candidate to account for shared PMDD and PD elevated challenge-induced panic. Psychological hypotheses suggest that anxiety symptoms themselves can cause fear. Because only anxiety sensitivity theory contends that fears of anxiety symptoms can result from factors other than direct panic experience, the possibility that PMDD and PD patients share elevated anxiety sensitivity warrants attention. A second controversy surrounding panic disorder concerns the diagnostic significance of respiratory symptoms during panic in PD. Klein proposes that respiratory symptoms distinguish the classic spontaneous panic attacks of panic disorder from other fearful reactions and demarcate a severe form of panic disorder. But findings from this work suggest that the diagnostic importance that Klein assigns to respiratory distress may be unwarranted. Respiratory symptoms during panic did not best differentiate PD respondents from non-claustrophobic respondents with only panic attack histories. Instead, fear of dying had the largest effect size. Similarly, hot flashes or chills, not respiratory symptoms, best differentiated non-claustrophobic simple phobics with panic attack histories from PD respondents. In PD respondents, respiratory distress itself did not predict greater impairment, beyond that accounted for by non-respiratory symptom endorsement. But heterogeneity was evident within PD respondents characterized by homogeneous respiratory distress; PD respondents whose respiratory distress was accompanied by fear of dying, relative to PD respondents with respiratory distress but without fear of dying, were significantly more impaired. A third controversy surrounding PD concerns whether panic disorder itself elevates suicide attempt risk. In this work, epidemiologic respondents with lifetime histories of panic disorder were not at heightened risk for self-reported suicide attempt, when psychiatric comorbidity was considered. Indeed, panic disorder respondents who had made a suicide attempt were characterized by comorbidity. These papers taken together are intended to advance understanding of the nature of panic disorder. |
