title: Effects of low-level sarin and cyclosarin exposure on hippocampal subfields in Gulf War Veterans.
abstract: BACKGROUND
  More than 100,000 US troops were potentially exposed to chemical warfare agents sarin (GB) and cyclosarin (GF) when an ammunition dump at Khamisiyah, Iraq was destroyed during the 1991 Gulf War (GW). We previously reported reduced hippocampal volume in GW veterans with suspected GB/GF exposure relative to matched, unexposed GW veterans estimated from 1.5T magnetic resonance images (MRI). Here we investigate, in a different cohort of GW veterans, whether low-level GB/GF exposure is associated with structural alterations in specific hippocampal subfields, estimated from 4T MRI.
  
  
  METHODS
  The Automatic Segmentation of Hippocampal Subfields (ASHS) technique was used to quantify CA1, CA2, CA3 and dentate gyrus (DG), and subiculum (SUB) subfields volumes from high-resolution T2-weighted images acquired on a 4T MR scanner in 56 GW veterans with suspected GB/GF exposure and 56 "matched" unexposed GW veterans (mean age 49±7 years).
  
  
  RESULTS
  GB/GF exposed veterans had smaller CA2 (p=0.003) and CA3/DG (p=0.01) subfield volumes compared to matched, unexposed GW veterans. There were no group difference in total hippocampal volume, quantified with FreeSurfer, and no dose-response relationship between estimated levels of GB/GF exposure and total hippocampal or subfield volume.
  
  
  CONCLUSIONS
  These findings extend our previous report of structural alterations in the hippocampi of GW veterans with suspected GB/GF exposure to volume changes in the CA2, CA3, and DG hippocampal subfields in a different cohort of GW veterans with suspected GB/GF exposure.
authors: Center for Imaging of Neurodegenerative Diseases, San Francisco Veterans Affairs Medical Center, 4150 Clement Street, 114M, San Francisco, CA 94121, United States; Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA, United States; Department of Psychiatry, University of California San Francisco, San Francisco, CA, United States. Electronic address: linda.chao@ucsf.edu.
authors: Linda L
authors: LL
authors: Chao
authors: Center for Imaging of Neurodegenerative Diseases, San Francisco Veterans Affairs Medical Center, 4150 Clement Street, 114M, San Francisco, CA 94121, United States.
authors: Stephen
authors: S
authors: Kriger
authors: Center for Imaging of Neurodegenerative Diseases, San Francisco Veterans Affairs Medical Center, 4150 Clement Street, 114M, San Francisco, CA 94121, United States.
authors: Shannon
authors: S
authors: Buckley
authors: Center for Imaging of Neurodegenerative Diseases, San Francisco Veterans Affairs Medical Center, 4150 Clement Street, 114M, San Francisco, CA 94121, United States.
authors: Peter
authors: P
authors: Ng
authors: Center for Imaging of Neurodegenerative Diseases, San Francisco Veterans Affairs Medical Center, 4150 Clement Street, 114M, San Francisco, CA 94121, United States; Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA, United States.
authors: Susanne G
authors: SG
authors: Mueller
mesh_terms: D002619:Chemical Warfare Agents / Q000633:toxicity*; D005260:Female; D047830:Gulf War; D006624:Hippocampus / Q000187:drug effects* / Q000473:pathology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009943:Organophosphorus Compounds / Q000633:toxicity*; D012524:Sarin / Q000633:toxicity*; D014728:Veterans
chemical_list: D002619:Chemical Warfare Agents; D009943:Organophosphorus Compounds; D012524:Sarin; C053914:cyclohexyl methylphosphonofluoridate
keywords: Cyclosarin; Gulf War veterans; Hippocampus; Magnetic resonance imaging; Sarin