The study included 17 patients with PTSD (assault n = 5, childhood abuse n = 3, military trauma n = 2, workplace trauma n = 2, motor vehicle collision n = 1, other n = 4) and 26 healthy controls who had experienced a criterion A traumatic event (military trauma n = 10, motor vehicle collision n = 8, assault n = 2, other n = 6) but never had PTSD. The participants were matched for age (mean age 36.8, standard deviation [SD] 8.2 yr in the control group v. 36.7, SD 9.7 yr in the PTSD group; t40 = 0.043, p = 0.97) and sex (female controls, n = 11; PTSD n = 9; Fisher exact test p = 0.54). Participants in the PTSD group exhibited the following current DSM-IV comorbid diagnoses: major depression (n = 5), dysthymia (n = 1), panic disorder (n = 2), anorexia (n = 1), generalized anxiety disorder (n = 1) and social phobia (n = 1). The 3 medicated patients with PTSD received fluoxetine (n = 1), quetiapine and bupropion (n = 1), and citalopram and olanzapine (n = 1).
Clinical rating scales and pain ratings
Significant group differences were established for all clinical rating scales (), including trait dissociation and state dissociation after exposure to the trauma script. There was no significant difference between hot (painful) and warm (nonpainful) temperatures chosen during thresholding by patients with PTSD and controls. After the traumatic script as compared with the neutral script, the painful stimulus was rated as significantly more painful (t25 = 2.502, p = 0.019) and unpleasant (t25 = 3.233, p = 0.003) in the control group (). We noted a tendency for lower pain ratings after the trauma script as compared with the neutral script in the PTSD group, although it failed to reach statistical significance. In a direct group comparison, patients with PTSD reported significantly lower pain intensity and unpleasantness after the trauma script than the control group.
Pain ratings, clinical rating scales and mean temperatures* of patients with PTSD and controls
Neuroimaging statistical parametric mapping analyses
All analyses presented refer to the comparison of hot (painful) stimulation with warm (nonpainful) stimulation and were covaried for use of medication.
Within-group analyses of pain perception after the traumatic script
Comparing pain perception after traumatic and neutral scripts, no significant differences in BOLD signal emerged for the control group. The PTSD group exhibited greater activations in the head of the left caudate ( and ).
Fig. 1 (A) Caudate: between-group results show greater activation in the posttramatic stress disorder (PTSD) group than the control group. (B) Thalamus: positive correlation with the Clinician Administered PTSD Scale29 in the PTSD group. (C) Amygdala: negative (more ...)
Blood oxygen level–dependent activations
Between-group analyses of pain perception
No significant group differences emerged after exposure to the neutral script.
Between-group analyses revealed that after exposure to the trauma script compared with the neutral script, activation of the head of the right caudate was significantly greater in the PTSD group than the control group during pain perception ().
The CAPS scores correlated positively with the BOLD signal after the trauma script in a number of areas implicated in stress-induced analgesia, such as the bilateral insulae, left thalamus, left caudate and left putamen. Activity in the right medial frontal gyrus (Brodmann area [BA] 9) was negatively correlated with CAPS scores ().
Correlations with CAPS scores in the PTSD group
The DES scores, a measure of trait dissociation, correlated negatively with the right amygdala, the left putamen, the right anterior cingluate cortex (BA 32) and the left superior frontal gyrus (BA 9, 10) in the PTSD group after the trauma script (). We detected no positive correlations. The CADSS scores, a measure of state dissociation, did not reveal any significant correlations with the BOLD signal in the ROIs in the PTSD group.
Negative correlations with DES scores in the PTSD group