Attention, learning, and memory performances and intellectual resources in Vietnam veterans: PTSD and no disorder comparisons

Neural networks of information processing in posttraumatic stress disorder: a functional magnetic resonance imaging study

BACKGROUND

Neuroimaging studies report reduced medial prefrontal cortical (particularly anterior cingulate) but enhanced amygdala response to fear signals in posttraumatic Stress Disorder (PTSD). We investigated whether anterior cingulate-amygdala dysregulation in PTSD would generalize to salient, but nonthreat related signals.

METHODS

Individuals with PTSD (n = 14) and age and sex-matched nontraumatized controls (n = 14) completed an auditory oddball paradigm adapted to functional magnetic resonance imaging at a 1.5-T field strength.

RESULTS

Controls displayed bilateral activation in ventral anterior cingulate and amygdala networks, and PTSD subjects showed bilateral dorsal anterior cingulate and amygdala activation to targets relative to nontargets. Compared to controls, PTSD subjects showed enhanced responses to targets in the dorsal and rostral anterior cingulate, and left amygdala. Whole-brain analyses confirmed the expected pattern of distributed prefrontal-parietal responses to targets in the oddball task. Greater activity in posterior parietal somatosensory regions was observed in PTSD.

CONCLUSIONS

Our findings of enhanced anterior cingulate responses in PTSD contrast with reports of reduced activity for threat stimuli, suggesting that the latter may be specific to processing of threat-related content. Activation in rostral and dorsal anterior cingulate, left amygdala and posterior parietal networks in response to salient, nonthreatening stimuli may reflect generalized hypervigilance.

Effects of phenytoin on memory, cognition and brain structure in post-traumatic stress disorder: a pilot study

Phenytoin (Dilantin) is an anticonvulsant used in the treatment of epilepsy. It is believed to act by modulation of glutamatergic transmission. Because the neurobiology of post-traumatic stress disorder (PTSD) has been hypothesized to involve alterations in glutamatergic transmission with subsequention neurotoxicity, we assessed the effects of phenytoin on cognition and brain structure in PTSD patients. Phenytoin was administered in an open label fashion for 3 months to nine adult patients with PTSD related to a variety of traumas, including early abuse, combat and car accidents. Subjects underwent magnetic resonance imaging for measurement of whole brain and hippocampal volume, and neuropsychological testing of memory and cognition, before and after treatment. Phenytoin treatment resulted in a significant 6% increase in right brain volume (p < 0.05). Increased hippocampal volume was correlated with reductions in symptom severity as measured by the Clinician Administered PTSD Scale and improvements in executive function as measured by the Trails test. However, treatment associated improvements in memory and cognition did not achieve statistical significance. These findings suggest that phenytoin treatment may be associated with changes in brain structure in patients with PTSD.

Effects of dexamethasone on declarative memory function in posttraumatic stress disorder

Alterations in the hypothalamic-pituitary-adrenal (HPA) axis and hippocampal-based memory have been associated with posttraumatic stress disorder (PTSD), and the administration of exogenous glucocorticoids has been shown to result in a transient verbal declarative memory impairment in healthy human subjects. The purpose of this study was to assess the effects of the glucocorticoid dexamethasone on verbal declarative memory function in patients with PTSD. Forty-two men and women with (n=14) and without (n=28) PTSD received placebo or dexamethasone (1 and 2 mg on two successive days) in a double-blind, randomized fashion. Declarative memory was assessed with paragraph recall at baseline (day 1) and day 3. There was a significant interaction between diagnosis and drug (dexamethasone vs. placebo) on paragraph recall related to a relative detrimental effect of dexamethasone on memory function in healthy subjects, but not those with PTSD. These findings are consistent with an altered sensitivity of declarative memory function in PTSD to regulation by glucocorticoids, possibly explainable by alterations in glucocorticoid receptors in the hippocampus or other brain regions mediating declarative memory.

Deficits in verbal declarative memory function in women with childhood sexual abuse-related posttraumatic stress disorder

Several studies have shown deficits in verbal declarative memory function in posttraumatic stress disorder (PTSD). Most of these studies have been performed in men with combat-related PTSD compared with healthy subjects; relatively little is known about memory function in women with abuse-related PTSD, or whether these effects are specific to PTSD or are a nonspecific outcome of exposure to early abuse. The purpose of this study was to assess declarative memory function in women with and without a history of early childhood sexual abuse and PTSD. Forty-three women with and without a history of early childhood sexual abuse and PTSD underwent neuropsychological testing with subtests of the Wechsler Memory Scale--Revised for measurement of verbal and visual memory and subtests of the Wechsler Adult Intelligence Scale for measurement of IQ, and behavioral ratings of PTSD and other psychiatric symptoms. Abused women with PTSD had deficits in verbal declarative memory as measured with the subtests of the Wechsler Memory Scale--Revised compared with women with early abuse without PTSD and nonabused women without PTSD. There were no significant differences in IQ. These findings suggest that early abuse with PTSD is associated with deficits in verbal declarative memory, and that these effects are not related to the nonspecific effects of childhood abuse.

Global-local visual processing in posttraumatic stress disorder

The purpose of this study was to examine a behavioral index of hemispheric asymmetry (i.e., visual hierarchical attention) in posttraumatic stress disorder (PTSD), a disorder characterized by anxiety and other emotional symptoms. A reaction time based, computerized, global-local visual paradigm was administered to 26 PTSD-diagnosed and 22 psychopathology-free right-handed, male Vietnam War zone veterans. Results indicated that PTSD-diagnosed veterans displayed slower reaction times to all targets than the no-mental disorders comparison sample. However, findings also revealed a Group x Target location interaction in which the PTSD group was slower than the no-disorders comparison sample to respond to local, but not global, targets. Moreover, relative global bias was greater among PTSD-diagnosed veterans than their no-diagnosis counterparts. Findings provide partial support for the hypothesis that PTSD may be associated with a functional cerebral asymmetry favoring the right hemisphere.

Neuropsychological function in college students with and without posttraumatic stress disorder

Previous research on the neuropsychology of posttraumatic stress disorder (PTSD) has identified several neurocognitive deficits that co-occur with the disorder. However, it remains unclear whether these deficits are due to trauma exposure, PTSD symptomatology or psychiatric/substance abuse comorbidity. We examined trauma exposure, PTSD symptoms and neuropsychological performance in 235 undergraduate students, i.e. a non-clinical sample. The sample comprised 146 subjects with trauma exposure (38 with current PTSD and 108 without lifetime PTSD) and 89 no-trauma comparison (NC) subjects who were administered tests of attention, working memory, psychomotor speed, word generation and executive functioning. Relationships of neuropsychological functioning to measures of psychiatric symptoms and substance abuse were examined. Current PTSD (PTSD+), trauma-exposed without PTSD (PTSD-) and NC subjects did not differ significantly on the vast majority of neuropsychological tests. There were very few significant associations between neuropsychological performance and clinical variables, and those that were statistically significant were small in magnitude. The striking lack of differences in neuropsychological performance between the three groups suggests that college students with trauma exposure, regardless of the presence of PTSD symptoms, may be cognitively resilient. Neuropsychological impairment may not be an invariant feature of PTSD, but when it is present, it may be associated with poorer functional outcomes.

Alterations of Myelin Basic Protein and Ultrastructure in the Limbic System at the Early Stage of Trauma-Related Stress Disorder in Dogs

BACKGROUND

The secondary injury and related complications after trauma are still the focus of trauma research. However, whether the remote effects on the central nervous system could be induced by high-energy missile extremity impact remains unclear. Also, the possible biomarker for brain damage in traumatic stress disorder has not been determined.

METHODS

Forty-two healthy adult dogs were divided into three groups: the control group (n = 12), the high-speed trauma group (n = 15), and the low-speed trauma group (n = 15). Bilateral thighs of dogs were wounded with a smoothbore 6.2-mm rifle at a speed of 1,368 m/s (1.03-g steel bullet) for the high-speed trauma group and 625 m/s for the low-speed trauma group. The expression of myelin basic protein (MBP) in cerebrospinal fluid (CSF), hypothalamus and hippocampus of the limbic system, and temporoparietal cortex was investigated by enzyme-linked immunosorbent assay and dot-blot analysis. Also, the ultrastructure of the above areas was observed with light and electron microscopy.

RESULTS

Neuronal degeneration and nerve fiber demyelination were seen in the hypothalamus and hippocampus in the high-speed trauma group at 8 hours after impact. The MBP level was markedly increased in the CSF (p < 0.01) in the two trauma groups, in the hypothalamus of the low-speed trauma group (p < 0.05), and in both the hypothalamus and the hippocampus of the high-speed trauma group (p < 0.01). The expression of MBP mRNA was also significantly enhanced in these areas at the same time. The increase of MBP content in the CSF was positively correlated with the elevation of MBP concentration in the hypothalamus and hippocampus.

CONCLUSION

The hypothalamus and hippocampus of the limbic system in the central nervous system are vulnerable to damage after high-energy missile extremity impact, indicating that it might be one of the important pathologic bases involved in the development of trauma-related complications. Meanwhile, the MBP level in the CSF may be a sensitive biological indicator for brain damage at the early stage of trauma-related stress disorder.

Progress and controversy in the study of posttraumatic stress disorder

Research on posttraumatic stress disorder (PTSD) has been notable for controversy as well as progress. This article concerns the evidence bearing on the most contentious issues in the field of traumatic stress: broadening of the definition of trauma, problems with the dose-response model of PTSD, distortion in the recollection of trauma, concerns about "phony combat vets," psychologically toxic guilt as a traumatic stressor, risk factors for PTSD, possible brain-damaging effects of stress hormones, recovered memories of childhood sexual abuse, and the politics of trauma.

Attention, learning, and memory in posttraumatic stress disorder

This study compared attention and declarative memory in a sample of combat veterans with posttraumatic stress disorder (PTSD, n = 24) previously reported to have reduced concentrations of the hippocampal neuronal marker N-acetyl aspartate (NAA), but similar hippocampal volume compared to veteran normal comparison participants (n = 23). Healthy, well-educated males with combat-related PTSD without current depression or recent alcohol/drug abuse did not perform differently on tests of attention, learning, and memory compared to normal comparison participants. Further, hippocampal volume, NAA, or NAA/Creatine ratios did not significantly correlate with any of the cognitive measures when adjustments for multiple comparisons were made. In this study, reduced hippocampal NAA did not appear to be associated with impaired declarative memory.

The accumulative effect of trauma exposure on short-term and delayed verbal memory in a treatment-seeking sample of female rape victims

The accumulative effect of prior high-magnitude trauma exposure on memory was examined in 73 rape victims, 92% of whom had current posttraumatic stress disorder (PTSD). Participants were administered the Logical Memory component of the Wechsler Memory Scale, the Quick Test to obtain an estimate of intelligence, and were assessed for prior traumatic experiences. Prior exposure to high-magnitude stressors (e.g., child rape, being kidnapped) was significantly correlated with poorer performance on the memory tasks. Regression analyses controlling for estimated IQ and psychopathology severity demonstrated that magnitude of prior trauma exposure predicted performance on the memory task, suggesting that in the current sample, deficits in verbal memory may be related (in part) to the degree of accumulative stress experienced over the lifetime.

Impaired memory following predatory stress in mice is improved by fluoxetine

The first purpose of the present study was to investigate possible effects of predatory stress (i.e., 5-min cat exposure) on short-term learning abilities in Swiss mice using the object recognition test (ORT). The second aim was to evaluate the effects of anxiolytics (i.e., diazepam and fluoxetine) on learning/memory abilities in the ORT following predatory stress. Results showed that predatory exposure impaired learning and produced amnesia of acquired information or impairment to retrieve learned information (48 and 96 h poststressor). The learning impairment in the ORT in stressed mice was restored by acute fluoxetine treatment, but not by diazepam that instead affected learning in nonstressed animals. Taken together, these findings indicate that this animal model of exposure of mice to unavoidable predatory stimuli produces early cognitive changes analogous to those seen in patients with acute stress disorder (ASD).

Long-term treatment with paroxetine increases verbal declarative memory and hippocampal volume in posttraumatic stress disorder

BACKGROUND

Animal studies have shown that stress is associated with damage to the hippocampus, inhibition of neurogenesis, and deficits in hippocampal-based memory dysfunction. Studies in patients with posttraumatic stress disorder (PTSD) found deficits in hippocampal-based declarative verbal memory and smaller hippocampal volume, as measured with magnetic resonance imaging (MRI). Recent preclinical evidence has shown that selective serotonin reuptake inhibitors promote neurogenesis and reverse the effects of stress on hippocampal atrophy. This study assessed the effects of long-term treatment with paroxetine on hippocampal volume and declarative memory performance in PTSD.

METHODS

Declarative memory was assessed with the Wechsler Memory Scale-Revised and Selective Reminding Test before and after 9-12 months of treatment with paroxetine in PTSD. Hippocampal volume was measured with MRI. Of the 28 patients who started the protocol, 23 completed the full course of treatment and neuropsychological testing. Twenty patients were able to complete MRI imaging.

RESULTS

Patients with PTSD showed a significant improvement in PTSD symptoms with treatment. Treatment resulted in significant improvements in verbal declarative memory and a 4.6% increase in mean hippocampal volume.

CONCLUSIONS

These findings suggest that long-term treatment with paroxetine is associated with improvement of verbal declarative memory deficits and an increase in hippocampal volume in PTSD.

Hypoactivation of the prefrontal cortex during verbal fluency test in PTSD: a near-infrared spectroscopy study

Several studies have suggested that there is frontal dysfunction in subjects with posttraumatic stress disorder (PTSD). We investigated the relationship between alterations of the hemodynamic response of the prefrontal cortex during a cognitive task (verbal fluency task; VFT) and memory function measured using the Wechsler Memory Scale-Revised (WMS-R). The subjects were victims of the Tokyo Subway Sarin attack with (n = 8) or without (n = 26) PTSD. Hemodynamic response in the prefrontal cortex was measured using a 24-channel near-infrared spectroscopy (NIRS) system. Subjects with PTSD had a significantly smaller response of oxygenated hemoglobin and total hemoglobin during the VFT compared with those without PTSD, although there was no significant difference in performance on the VFT. Subjects with PTSD had significantly lower scores on attention and concentration in the WMS-R, which was positively correlated with the increase of total hemoglobin during the VFT. The 'frontal dysfunction' observed in subjects with PTSD may be a secondary phenomenon to reduced attentional capacity.

Psychological theories of posttraumatic stress disorder

We summarize recent research on the psychological processes implicated in posttraumatic stress disorder (PTSD) as an aid to evaluating theoretical models of the disorder. After describing a number of early approaches, including social-cognitive, conditioning, information-processing, and anxious apprehension models of PTSD, the article provides a comparative analysis and evaluation of three recent theories: Foa and Rothbaum's [Foa, E. B. & Rothbaum, B. O. (1998). Treating the trauma of rape: cognitive behavioral therapy for PTSD. New York: Guilford Press] emotional processing theory; Brewin, Dalgleish, and Joseph's [Psychological Review 103 (1996) 670] dual representation theory; Ehlers and Clark's [Behaviour Research and Therapy 38 (2000) 319] cognitive theory. We review empirical evidence relevant to each model and identify promising areas for further research.

Psychological mechanisms in acute response to trauma

Traumatic events are common, but posttraumatic stress disorder (PTSD) is relatively rare. These facts have prompted several questions: What variables increase risk for PTSD among trauma-exposed people? Can we distinguish between pathologic and nonpathologic responses to traumatic stressors? If so, what psychobiological mechanisms mediate pathologic responses? Prospective studies have identified certain individual difference variables as heightening risk (e.g., lower intelligence, negative personality traits). Studies on peritraumatic and acute-phase response have identified certain dissociative symptoms (e.g., time slowing, derealization) and cognitive appraisal (e.g., belief that one is about to die) as harbingers of later PTSD. Negative appraisal of acute symptoms themselves may foster chronic morbidity (e.g., that symptoms signify shameful moral weakness or prefigure impending psychosis). Further attempts to elucidate pathologic mechanisms in the cognitive psychology laboratory and via biological challenges are warranted.

Neuropsychological function in female victims of intimate partner violence with and without posttraumatic stress disorder

BACKGROUND

Various aspects of neuropsychologic function have been reported to be abnormal in patients with posttraumatic stress disorder (PTSD); however, the majority of these data come from studies of seriously ill, treatment-seeking samples with substantial substance use comorbidity. Few studies have included similarly trauma-exposed subjects without PTSD, and fewer still have focused on women.

METHODS

Thirty-nine female victims of intimate partner violence (IPV; 22 without lifetime PTSD and 17 with current PTSD), and 22 nonvictimized comparison (NC) subjects were administered tests of attention, working memory, visuoconstruction, language ability, learning and memory, and executive functioning.

RESULTS

The IPV and NC subjects did not demonstrate statistically significant differences on most neuropsychologic tests, with the exception of those in the realm of working memory, visuoconstruction, and executive functioning. The IPV subjects, regardless of PTSD status, had poorer performance on tasks of speeded, sustained auditory attention and working memory (Paced Auditory Serial Addition Test) and response inhibition (Stroop). The IPV subjects with PTSD performed worse than NCs on a set-shifting task (Trail Making Test, Part B). No consistent relationships were noted between neuropsychologic functioning and severity of childhood abuse or domestic violence experiences.

CONCLUSIONS

Cognitive deficits in IPV subjects were confined to measures of working memory, visuoconstruction, and executive function; were subtle; and were not uniformly worse among those with current PTSD. This pattern, however, is consistent with frontal-subcortical dysfunction in traumatized women. The clinical significance of these findings deserves further study.