Altered pain processing in veterans with posttraumatic stress disorder.

CONTEXT

Posttraumatic stress disorder (PTSD) is a chronic and debilitating anxiety disorder. Several brain areas related to pain processing are implicated in PTSD. To our knowledge, no functional imaging study has discussed whether patients with PTSD experience and process pain in a different way than control subjects.

OBJECTIVE

To examine neural correlates of pain processing in patients with PTSD.

DESIGN

The experimental procedure consisted of psychophysical assessment and neuroimaging with functional magnetic resonance imaging. Two conditions were assessed during functional magnetic resonance imaging in both experimental groups, one condition with administration of a fixed temperature of 43 degrees C (fixed-temperature condition) and the other condition with an individual temperature for each subject but with a similar affective label equaling 40% of the subjective pain intensity (individual temperature condition).

SETTING

Academic outpatient unit in a department of military psychiatry in collaboration with an imaging center at a psychiatric hospital.

PARTICIPANTS

Twelve male veterans with PTSD and 12 male veterans without PTSD were recruited and matched for age, region of deployment, and year of deployment.

MAIN OUTCOME MEASURES

Changes in functional magnetic resonance imaging blood oxygenation level-dependent response to heat stimuli, reflecting increased and decreased activity of brain areas involved in pain processing.

RESULTS

Patients with PTSD rated temperatures in the fixed-temperature assessment as less painful compared with controls. In the fixed-temperature condition, patients with PTSD revealed increased activation in the left hippocampus and decreased activation in the bilateral ventrolateral prefrontal cortex and the right amygdala. In the individual temperature condition, patients with PTSD showed increased activation in the right putamen and bilateral insula, as well as decreased activity in the right precentral gyrus and the right amygdala.

CONCLUSIONS

These data provide evidence for reduced pain sensitivity in PTSD. The witnessed neural activation pattern is proposed to be related to altered pain processing in patients with PTSD.