title: Hippocampal function in posttraumatic stress disorder.
abstract: Recent studies have reported memory deficits and reduced hippocampal volumes in posttraumatic stress disorder (PTSD). The goal of the current research was to use functional neuroimaging and a validated explicit memory paradigm to examine hippocampal function in PTSD. We used positron emission tomography (PET) and a word-stem completion task to study regional cerebral blood flow (rCBF) in the hippocampus in 16 firefighters: 8 with PTSD (PTSD group) and 8 without PTSD (Control group). During PET scanning, participants viewed three-letter word stems on a computer screen and completed each stem with a word they had previously encoded either deeply (High Recall condition) or shallowly (Low Recall condition). Relative to the Control group, the PTSD group exhibited significantly smaller rCBF increases in the left hippocampus in the High vs Low Recall comparison. However, this finding reflected relatively elevated rCBF in the Low Recall condition in the PTSD group. Collapsing across High and Low Recall conditions, (1) the PTSD group had higher rCBF in bilateral hippocampus and left amygdala than the Control group, and (2) within the PTSD group, symptom severity was positively associated with rCBF in hippocampus and parahippocampal gyrus. The groups did not significantly differ with regard to accuracy scores on the word-stem completion task. The PTSD group had significantly smaller right (and a trend for smaller left) hippocampal volumes than the Control group. The results suggest an abnormal rCBF response in the hippocampus during explicit recollection of nonemotional material in firefighters with PTSD, and that this abnormal response appears to be driven by relatively elevated hippocampal rCBF in the comparison condition.
authors.affiliation: Department of Psychology, Tufts University, 490 Boston Avenue, Medford, MA 02155, USA. lisa.shin@tufts.edu
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Shin
authors.forename: Patrick S
authors.initials: PS
authors.lastname: Shin
authors.forename: Stephan
authors.initials: S
authors.lastname: Heckers
authors.forename: Terri S
authors.initials: TS
authors.lastname: Krangel
authors.forename: Michael L
authors.initials: ML
authors.lastname: Macklin
authors.forename: Scott P
authors.initials: SP
authors.lastname: Orr
authors.forename: Natasha
authors.initials: N
authors.lastname: Lasko
authors.forename: Ethan
authors.initials: E
authors.lastname: Segal
authors.forename: Nikos
authors.initials: N
authors.lastname: Makris
authors.forename: Katherine
authors.initials: K
authors.lastname: Richert
authors.forename: Jeff
authors.initials: J
authors.lastname: Levering
authors.forename: Daniel L
authors.initials: DL
authors.lastname: Schacter
authors.forename: Nathaniel M
authors.initials: NM
authors.lastname: Alpert
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Fischman
authors.forename: Roger K
authors.initials: RK
authors.lastname: Pitman
authors.forename: Scott L
authors.initials: SL
authors.lastname: Rauch
mesh_terms: D000328:Adult; D001284:Atrophy / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D002560:Cerebrovascular Circulation / Q000502:physiology*; D002561:Cerebrovascular Disorders / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006624:Hippocampus / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D009784:Occupational Diseases / Q000209:etiology / Q000503:physiopathology; D020534:Parahippocampal Gyrus / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D013313:Stress Disorders, Post-Traumatic / Q000150:complications / Q000503:physiopathology* / Q000523:psychology; D014055:Tomography, Emission-Computed