Positron tomographic emission study of olfactory induced emotional recall in veterans with and without combat-related posttraumatic stress disorder.

Full Abstract

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.

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Author information

Author/s: Vermetten, Eric (E); Schmahl, Christian (C); Southwick, Steven M (SM); Bremner, J Douglas (JD);

Affiliation: University Medical Center, Utrecht, The Netherlands. e.vermetten(-atsign-)umcutrecht.nl

Grants: 1R01MH56120-01A1 (Agency:NIMH NIH HHS)

Journal and publication information

Publication Type: Journal Article; Research Support, N.I.H., Extramural; Research Support, U.S. Gov't, Non-P.H.S.

Journal: Psychopharmacology bulletin (Psychopharmacol Bull), published in United States. (Language: eng)

Reference: 2007-; vol 40 (issue 1) : pp 8-30

Dates: Created 2007/02/07; Completed 2007/05/02; Revised 2007/12/03;

PMID: 17285093, status: MEDLINE (last retrieval date: 12/26/2008)

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Adult
Amygdala - blood supply; radionuclide imaging
Brain - blood supply; radionuclide imaging
Brain Mapping
Combat Disorders - radionuclide imaging
Emotions - physiology
Humans
Male

Male
Mental Recall - physiology
Middle Aged
Olfactory Pathways - blood supply; radionuclide imaging
Positron-Emission Tomography
Regional Blood Flow - physiology
Smell - physiology
Veterans - psychology

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