Faculty Bibliography

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.

Posttraumatic stress disorder (PTSD) is an anxiety disorder associated with changes in neural circuitry involving frontal and limbic systems. Altered metabolism in these brain structures after a traumatic event is correlated to PTSD. Developments in the field of neuroimaging have allowed researchers to look at the structural and functional properties of the brain in PTSD. Despite the relative novelty of functional imaging and its application to the field of PTSD, numerous publications have brought to light several of the circuits implied in this disorder. This article summarizes the findings with regard to PTSD in the functional imaging techniques of single-photon emission computed tomography (SPECT), positron emission tomography (PET), and functional magnetic resonance imaging (fMRI). Furthermore, we discuss strengths and weaknesses of the various techniques and studies. Finally, we explore the future potential of functional neuroimaging studies in PTSD.

OBJECTIVE: Memory for odors is often associated with highly emotional experiences, and odors have long been noted by clinicians to be precipitants of trauma symptoms in posttraumatic stress disorder (PTSD). Primitive brain systems involved in fear responsivity and survival also mediate smell, including the olfactory cortex and amygdala. The purpose of this study was to measure neural correlates of olfaction in PTSD. METHODS: We exposed male combat veterans with PTSD (N = 8) and without PTSD (N = 8) to a set of smells, including diesel (related to traumatic memories of combat), and three other types of smells: odorless air, vanilla/coconut, and hydrogen sulfide (H2S) (respectively, a neutral, positive, and negative hedonic nontraumatic smell) in conjunction with PET imaging of cerebral blood flow and assessment of psychophysiological and behavioral symptoms. All subjects also underwent a baseline of olfactory acuity. RESULTS: PTSD patients rated diesel as unpleasant and distressing, resulting in increased PTSD symptoms and anxiety in PTSD versus combat controls. Exposure to diesel resulted in an increase in regional blood flow (rCBF) in amygdala, insula, medial prefrontal cortex, and anterior cingulate cortex, and decreased rCBF in lateral prefrontal cortex in PTSD in comparison to combat controls. Combat controls showed less rCBF changes on any smell, and did not show amygdala activation upon diesel exposure. CONCLUSIONS: These data support the hypothesis that in PTSD trauma-related smells can serve as strong emotional reminders. The findings indicate the involvement of a neural circuitry that shares olfactory elements and memory processing regions when exposed to trauma-related stimuli.

BACKGROUND: Nightmares and insomnia are experienced by 70% of patients suffering from post-traumatic stress disorder (PTSD). These sleep problems are often resistant to treatment and exert a strong negative influence on the quality of life. In the last few decades several studies have reported on the characteristics of sleep disturbances in PTSD. AIM: To provide an overview of objective features of sleep disturbances - as opposed to self-report methods - in patients with PTSD. METHOD: Articles on this topic, published in peer-reviewed journals between 1980 and the present, were retrieved from Medline and Embase, using the search terms 'PTSD', 'sleep', 'nightmares', 'insomnia', 'polysomnography'. RESULTS: Studies reported on changes in sleep efficiency, arousal regulation, motor activity during sleep, rem characteristics and delta sleep activity during sleep. Also, correlations were found between nightmares and sleep apnoea in ptsd. In some studies on sleep disturbance no objective sleep disturbances were found in PTSD patients. However, most studies on PTSD related sleep disturbances were conducted in small, heterogeneous groups, and results were therefore inconsistent. Even the results of larger and more homogeneous studies were sometimes contradictory. CONCLUSION: There is a discrepancy between the clinical importance of sleep problems in PTSD and unambiguous objective sleep disorders. Future research should try to establish objective criteria for identifying the altered sleep patterns in PTSD. These criteria should help us to understand the neurobiological mechanisms of sleep disturbances in PTSD and develop new treatment strategies.