PTSD, Co-morbid Anxiety Disorders and Emotional Reactivity

Lisa M. McTeague, Gainesville, Florida

Lisa M. McTeague is the 2003 recipient of the ISTSS Student Poster Award. The following is a summary of the winning poster that was presented at the ISTSS 19th Annual Meeting.

In current diagnostic practice, physiological hyperarousal is considered a hallmark symptom of posttraumatic stress disorder (PTSD). Curiously, when reactions are objectively assessed in the psychophysiological laboratory, PTSD patients do not always show the expected greater reactivity. In an effort to understand this inconsistency, physiological reactions were systematically measured in PTSD patients (N=34) and demographically matched controls (N=49) as these participants listened to emotionally evocative scripts and then imagined that they were participating personally in the events described.

The imagery scripts depicted a variety of pleasant, neutral and unpleasant emotional scenes. These standard scripts were presented to all participants, along with an idiographic fear script related to the primary anxiety diagnosis. Startle probes were presented aperiodically during all phases of the experiment. Reflex magnitude was assessed, and heart rate and cell firing in the corrugator (frown) muscle were continuously recorded.

Diagnoses were established, using the Anxiety Disorder Interview Schedule for DSM-IV (ADIS-IV; Brown et al., 1994). For some analyses, the PTSD sample was further divided into two subgroups--one group for which PTSD was the principal anxiety diagnosis, and a second group with clear, clinically significant PTSD but with a different principal, co-morbid anxiety diagnosis (e.g., panic, GAD). The subgroups did not differ in trauma type, chronicity or prevalence of depressive symptoms.

Affective judgments differed, as expected, for neutral, pleasant and unpleasant scripts, and these reports of experienced emotion were equivalent for all groups. Furthermore, PTSD patients and controls did not differ in average startle probe magnitude. However, while the controls showed the usual startle modulation--greater reactivity for emotional scripts than for neutral scripts--these content differences were not apparent for PTSD patients.

Controls and PTSD patients differed significantly in heart rate, as the patients showed a general, markedly diminished response to emotional challenge, and particularly to the pleasant scripts. The analysis of PTSD subgroups showed that this pattern appeared mainly in the anxiety co-morbid PTSD patients. PTSD and control participants did not differ overall in frown muscle activity. However, again in the subgroup analysis, the patients with prominent, co-morbid anxiety diagnoses differed, showing less of an expected corrugator relaxation to the pleasant scenes than did patients for whom PTSD was the principal diagnosis.

The experiment yielded very little evidence of the exaggerated arousal response in PTSD that is typically reported in clinical interviews. On the contrary, the results suggest that physiological reactivity during emotional processing may be diminished, especially in response to pleasant cues. This reduced reaction was found particularly in PTSD patients with another principal anxiety diagnosis. Psychophysiological studies to date have rarely considered the role of co-morbid anxiety reactions in PTSD. The present findings for heart rate and facial action suggest that PTSD patients with another dominant anxiety disorder are a special subgroup. Given the apparent deficit in appetitive responding, these patients may have a different prognosis than patients whose anxiety is predominantly focused on trauma, which may warrant modification to the usual PTSD treatment plan.

Lisa M. McTeague, MS, is a graduate student in the Department of Clinical and Health Psychology at the University of Florida. In addition to winning the 2003 ISTSS Student Poster Award, McTeague has been honored with an NRSA predoctoral fellowship to investigate physiological reactivity in PTSD.