Longitudinal associations between self-reported experiences of discrimination and depressive symptoms in young women and men post- myocardial infarction

Objectives

Research suggests that following a myocardial infarction (MI), women under the age of 60 have more elevated depressive symptoms and adverse outcomes than similarly aged men. Identifying risk factors that contribute to gender differences in depressive symptoms among this group may be critical to the development of psychosocial interventions. Experiences of discrimination may be an important correlate of depressive symptoms in this group; however, studies of this relationship have largely been cross-sectional and focused on healthy populations. This study examines longitudinal associations among gender, discrimination, and depressive symptoms in a young post-MI cohort.

Methods

Participants were 313 adults from the Myocardial Infarction and Mental Stress Ischemia Study 2 of young (≤60 yrs) post-MI patients. At baseline and 6 month follow-up, depressive symptoms were measured with the Beck Depression Inventory-II and discrimination was assessed with the 10-item version Everyday Discrimination scale. Linear regression models were used to assess the longitudinal association between reports of discrimination and depressive symptoms adjusted for sociodemographic characteristics, psychosocial factors and health status indicators and tested for gender differences.

Results

The mean age was 51.2, 49.6% were women, and 69.5% were African-American. Although the discrimination-by-gender interaction was marginally significant (p=.09) in the fully adjusted model, findings suggest that the association between changes in reports of discrimination and depressive symptoms over time may be more pronounced for women (β=.61, standard error=.15, p<.001) than men (β=.27, standard error=.13, p=.033).

Conclusion

Our findings suggest that discrimination is a risk factor for depressive symptoms in young post-MI populations over time.

Script-driven imagery of self-injurious behavior in patients with borderline personality disorder: a pilot FMRI study

OBJECTIVE

Self-injurious behavior (SIB) is one of the most distinctive features of borderline personality disorder (BPD) and related to impulsivity and emotional dysregulation.

METHOD

Female patients with BPD (n = 11) and healthy controls (n = 10) underwent functional magnetic resonance imaging while listening to a standardized script describing an act of self-injury. Experimental sections of the script were contrasted to the neutral baseline section and group-specific brain activities were compared.

RESULTS

While imagining the reactions to a situation triggering SIB, patients with BPD showed significantly less activation in the orbitofrontal cortex compared with controls. Furthermore, only patients with BPD showed increased activity in the dorsolateral prefrontal cortex during this section and a decrease in the mid-cingulate while imagining the self-injurious act itself.

CONCLUSION

This pattern of activation preliminary suggests an association with diminished emotion regulation, impulse control as well as with response selection and reappraisal during the imagination of SIB.

Heritability of flow-mediated dilation: a twin study

BACKGROUND

Endothelial dysfunction assessed by brachial artery flow-mediated dilation (FMD) is a marker for early atherosclerotic vascular disease and future cardiovascular events.

OBJECTIVE

To estimate the heritability of brachial artery FMD using a twin design.

METHODS

We estimated the heritability of FMD using 94 middle-aged male twin pairs. FMD was measured by ultrasound, and traditional coronary heart disease risk factors were measured. Genetic modeling techniques were used to determine the relative contributions of genes and environment to the variation in FMD.

RESULTS

The mean age of the twin participants was 54.9 +/- 2.8 years. The mean FMD was 0.047 +/- 0.030. The intraclass correlation coefficient was higher in MZ twins [0.38, 95% confidence interval (CI) 0.32-0.43] than in DZ twins (0.19, 95% CI 0.11-0.26), suggesting a role of genetic influence in FMD variation. Structural equation modeling showed that both genetic and unique environmental factors contributed significantly to the variation in FMD. The crude FMD heritability was 0.37 (95% CI 0.15-0.54). After adjustment for traditional cardiovascular risk factors, including age, total cholesterol, blood pressure, and body mass index, the heritability of FMD was 39% (95% CI 0.18-0.56). The remaining variation in FMD could be explained by individual-specific environment.

CONCLUSION

This is the first study using twins to estimate the relative contributions of genetics and environment to the variation in FMD in a US population. Our results demonstrate a moderate genetic effect on brachial artery FMD, independent of traditional coronary risk factors. Our data also highlight the importance of unique environment on the variability in FMD.

Functional neuroimaging studies in posttraumatic stress disorder: review of current methods and findings

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.

MR-based in vivo hippocampal volumetrics: 1. Review of methodologies currently employed

The advance of neuroimaging techniques has resulted in a burgeoning of studies reporting abnormalities in brain structure and function in a number of neuropsychiatric disorders. Measurement of hippocampal volume has developed as a useful tool in the study of neuropsychiatric disorders. We reviewed the literature and selected all English-language, human subject, data-driven papers on hippocampal volumetry, yielding a database of 423 records. From this database, the methodology of all original manual tracing protocols were studied. These protocols differed in a number of important factors for accurate hippocampal volume determination including magnetic field strength, the number of slices assessed and the thickness of slices, hippocampal orientation correction, volumetric correction, software used, inter-rater reliability, and anatomical boundaries of the hippocampus. The findings are discussed in relation to optimizing determination of hippocampal volume.

MR-based in vivo hippocampal volumetrics: 2. Findings in neuropsychiatric disorders

Magnetic resonance imaging (MRI) has opened a new window to the brain. Measuring hippocampal volume with MRI has provided important information about several neuropsychiatric disorders. We reviewed the literature and selected all English-language, human subject, data-driven papers on hippocampal volumetry, yielding a database of 423 records. Smaller hippocampal volumes have been reported in epilepsy, Alzheimer's disease, dementia, mild cognitive impairment, the aged, traumatic brain injury, cardiac arrest, Parkinson's disease, Huntington's disease, Cushing's disease, herpes simplex encephalitis, Turner's syndrome, Down's syndrome, survivors of low birth weight, schizophrenia, major depression, posttraumatic stress disorder, chronic alcoholism, borderline personality disorder, obsessive-compulsive disorder, and antisocial personality disorder. Significantly larger hippocampal volumes have been correlated with autism and children with fragile X syndrome. Preservation of hippocampal volume has been reported in congenital hyperplasia, children with fetal alcohol syndrome, anorexia nervosa, attention-deficit and hyperactivity disorder, bipolar disorder, and panic disorder. Possible mechanisms of hippocampal volume loss in neuropsychiatric disorders are discussed.

Cortisol response to a cognitive stress challenge in posttraumatic stress disorder (PTSD) related to childhood abuse

Preclinical studies show that animals with a history of chronic stress exposure have increased hypothalamic-pituitary-adrenal (HPA) axis reactivity following reexposure to stress. Patients with posttraumatic stress disorder (PTSD) have been found to have normal or decreased function of the HPA axis, however no studies have looked at the HPA response to stress in PTSD. The purpose of this study was to assess cortisol responsivity to a stressful cognitive challenge in patients with PTSD related to childhood abuse. Salivary cortisol levels, as well as heart rate and blood pressure, were measured before and after a stressful cognitive challenge in patients with abuse-related PTSD (N=23) and healthy comparison subjects (N=18). PTSD patients had 61% higher group mean cortisol levels in the time period leading up to the cognitive challenge, and 46% higher cortisol levels during the time period of the cognitive challenge, compared to controls. Both PTSD patients and controls had a similar 66-68% increase in cortisol levels from their own baseline with the cognitive challenge. Following the cognitive challenge, cortisol levels fell in both groups and were similar in PTSD and control groups. PTSD patients appeared to have an increased cortisol response in anticipation of a cognitive challenge relative to controls. Although cortisol has been found to be low at baseline, there does not appear to be an impairment in cortisol response to stressors in PTSD.

Positron emission tomography in female patients with borderline personality disorder

The pathology of Borderline personality disorder (BPD) is poorly understood and its biological basis remains largely unknown. One functional brain imaging study using [(18)F]Deoxyglucose-PET previously reported frontal and prefrontal hypometabolism. We studied brain metabolism at baseline in 12 medication-free female patients with BPD without current substance abuse or depression and 12 healthy female controls by [(18)F]Deoxyglucose-PET and statistical parametric mapping. We found significant frontal and prefrontal hypermetabolism in patients with BPD relative to controls as well as significant hypometabolism in the hippocampus and cuneus. This study demonstrated limbic and prefrontal dysfunction under resting conditions in patients with BPD by FDG-PET. Dysfunction in this network of brain regions, which has been implicated in the regulation of emotion, may underlie symptoms of BPD.

Gender differences in cognitive and neural correlates of remembrance of emotional words

Studies suggest that men and women have important differences in specific cognitive functions. Men show superior spatial memory and women demonstrate superior verbal memory, and women rely on emotional content to a greater degree in the processing of information. In spite of extensive research in neural correlates of human cognition, little is known about possible gender differences or the role of emotional content in the mediation of cognition. Two sets of lists of word pairs were developed, one with neutral (e.g., school-grocery) and the other with emotional (e.g., mutilate-beat) content. Male and female subjects were asked to rate emotions related to the words on several dimensions (e.g., nervous, fearful, happy). In a second experiment, men and women underwent positron emission tomographic (PET) measurement of brain blood flow during retrieval of word pairs. Words in the "emotional" category were rated more highly on the emotional dimensions, and women rated them as having more emotional impact than did the men. During retrieval of emotional words (but not neutral words) there was a different pattern of activation among the women compared with the men, with greater activation in bilateral posterior hippocampus and cerebellum, and decreased activity in medial prefrontal cortex, which are brain areas previously implicated in emotion. There were no significant differences in retrieval of emotional versus neutral words, or in differences in memory performance between men and women. The findings suggest differences in cognitive appraisal and involvement of a broader network of brain regions mediating emotion during remembrance of emotional words in women compared with men.

Are the neural substrates of memory the final common pathway in posttraumatic stress disorder (PTSD)?

A model for the posttraumatic stress disorder (PTSD) as a disorder of memory is presented drawing both on psychological and neurobiological data. Evidence on intrusive memories and deficits in declarative memory function in PTSD-patients is reviewed in relation to three brain areas that are involved in memory functioning and the stress response: the hippocampus, amygdala, and the prefrontal cortex. Neurobiological studies have shown that the noradrenergic stress-system is involved in enhanced encoding of emotional memories, sensitization, and fear conditioning, by way of its effects on the amygdala. Chronic stress also affects the hippocampus, a brain area involved in declarative memories, suggesting that hippocampal dysfunction may partly account for the deficits in declarative memory in PTSD-patients. Deficits in the medial prefrontal cortex, a structure that normally inhibits the amygdala, may further enhance the effects of the amygdala, thereby increasing the frequency and intensity of the traumatic memories. Thus, by way of its influence on these brain structures, exposure to severe stress may simultaneously result in strong emotional reactions and in difficulties to recall the emotional event. This model is also relevant for understanding the distinction between declarative and non-declarative memory-functions in processing trauma-related information in PTSD. Implications of our model are reviewed.

Increased pituitary and adrenal reactivity in premenopausal women with posttraumatic stress disorder

BACKGROUND

Limited studies of hypothalamic-pituitary-adrenal axis regulation in posttraumatic stress disorder have been performed in premenopausal women. We therefore undertook a study of hypothalamic-pituitary-adrenal axis regulation in this population.

METHODS

Outpatient posttraumatic stress disorder subjects were compared with healthy, age- and weight-matched nontraumatized subjects. Subjects were free from psychotropic medications, alcohol and other illicit substances for at least 4 weeks before study. Menstrual cycle phase was determined by monitoring the LH surge and plasma progesterone levels. Corticotropin releasing factor and adrenocorticotropin stimulation tests, as well as 24-hour urinary-free cortisol measurements were performed.

RESULTS

Corticotropin releasing factor test: Baseline adrenocorticotropic hormone and cortisol levels did not differ between the 12 PTSD and 11 comparison subjects, but the posttraumatic stress disorder group had greater adrenocorticotropic hormone and cortisol responses to corticotropin releasing factor, as well as a later cortisol peak. Adrenocorticotropic hormone test: Baseline cortisol levels did not differ between the 10 posttraumatic stress disorder subjects and seven controls, but the posttraumatic stress disorder group showed greater cortisol responses to adrenocorticotropic hormone. Peak cortisol responses to corticotropin releasing factor and adrenocorticotropic hormone were correlated with each other and with 24-hour urinary-free cortisol excretion.

CONCLUSIONS

Pituitary and adrenal hyperreactivity to exogenous corticotropin releasing factor and adrenocorticotropic hormone is demonstrated in premenopausal women with chronic posttraumatic stress disorder. Cortisol hyperreactivity thus may play a role in the pathophysiology of posttraumatic stress disorder in women.

Development and preliminary psychometric properties of an instrument for the measurement of childhood trauma: the Early Trauma Inventory

Research on the effects of childhood trauma has been limited by the lack of a comprehensive, reliable, and valid instrument that assesses the occurrence of early traumatic experiences. This paper presents the development and preliminary psychometric properties of an instrument, the Early Trauma Inventory (ETI), for the assessment of reported childhood trauma. The clinician-administered ETI is a 56-item interview for the assessment of physical, emotional, and sexual abuse, as well as general traumatic experience (including items which range from parental loss to natural disaster). For each item of the ETI, frequency of abuse/trauma by developmental stage, onset and termination of abuse/trauma, perpetrator of the abuse/trauma, and impact on the individual are assessed. Initial analyses indicate acceptable inter-rater reliability, test-retest reliability, and internal consistency for the ETI. Comparisons between the ETI and other instruments for the assessment of trauma, as well as instruments for the measurement of symptoms related to abuse, such as dissociation and PTSD, demonstrated good convergent validity. Validity was also demonstrated based on the ability of the ETI to discriminate patients with PTSD from comparison subjects. Based on these findings, the ETI appears to be a reliable and valid instrument for the measurement of reported childhood trauma.

Cerebrospinal fluid corticotropin-releasing hormone in healthy humans: effects of yohimbine and naloxone

CRH neurons projecting from the paraventricular nucleus (PVN) of the hypothalamus to the median eminence control hypothalamic-pituitary-adrenal (HPA) axis activity. However, CRH neurons outside the PVN as well as PVN neurons projecting to sites other than the median eminence also contribute to the stress response and may play a role in mood and anxiety disorders. We have attempted to investigate possible noradrenergic and opioid regulation of these non-HPA CRH neurons. We hypothesized that yohimbine (an alpha2-adrenergic antagonist) would have stimulatory action on non-HPA CRH neurons, whereas naloxone (a mu-opioid receptor antagonist) would not have this effect. Adult normal volunteers received i.v. yohimbine (n = 5; 0.4 microg/kg), naloxone (n = 4; 125 microg/kg), or placebo (n = 3; 0.9% saline). Cerebrospinal fluid (CSF) was collected continuously, and concentrations of CSF CRH, CSF norepinephrine (NE), and plasma cortisol were measured. Administration of either yohimbine or naloxone caused significant increases in plasma cortisol concentrations over time. Although yohimbine robustly increased CSF NE levels and appeared to increase CSF CRH levels, these effects were not seen after naloxone or placebo administration. Intraindividual correlations were not observed between the measured concentrations of plasma cortisol and CSF CRH for any of the subjects. The results support the idea that CSF CRH concentrations reflect the activity of non-HPA CRH neurons. Although both yohimbine and naloxone stimulated the HPA axis, only yohimbine appeared to have stimulatory effects on central NE and non-HPA CRH.

Temporal lobe volume in panic disorder--a quantitative magnetic resonance imaging study

Although previous studies have used magnetic resonance imaging (MRI) to demonstrate qualitative abnormalities of the temporal lobes in patients with panic disorder, no study to date has applied quantitative volumetric methods to evaluate brain changes in panic disorder. The purpose of this study was to measure the volume of the temporal lobe and the hippocampus in patients with panic disorder and healthy control subjects using quantitative MRI measures. The volume of the temporal lobe, hippocampus and whole brain was measured in 13 patients with panic disorder and 14 healthy subjects. The mean volume of the left and right temporal lobes was significantly smaller in panic disorder compared to healthy subjects (16770+/-909 mm(3) vs. 18343+/-1740 mm(3)). This result was significant after controlling for differences in whole brain volume. There was no significant difference in volume of the hippocampus between patients and control subjects. These findings are consistent with smaller temporal lobe volume in panic disorder despite normal hippocampal volume.

False memories in women with self-reported childhood sexual abuse: an empirical study

Although controversy exists about the validity of memories of childhood abuse, little is known about memory function in individuals reporting childhood abuse. This study assessed memories for previously presented words, including the capacity for false memory of critical lures not actually present in the word list, in 63 subjects, including abused women with posttraumatic stress disorder (PTSD), abused women without PTSD, and men and women without abuse or PTSD. Abused women with PTSD had a higher frequency of false recognition memory of critical lures (95%) than abused women without PTSD (78%), nonabused women without PTSD (79%), or nonabused men without PTSD (86%). PTSD women also showed poorer memory for studied words and increased insertions of non-studied words other than critical lures. These findings are consistent with a broad range of memory alterations in abused women with PTSD.

Decreased benzodiazepine receptor binding in prefrontal cortex in combat-related posttraumatic stress disorder

OBJECTIVE

Animals exposed to stress exhibit a decrease in benzodiazepine receptor binding in the frontal cortex. No studies have examined central benzodiazepine receptor binding in patients with posttraumatic stress disorder (PTSD). The purpose of this study was to examine measures of benzodiazepine receptor binding in PTSD.

METHOD

From 13 patients with Vietnam combat-related PTSD and 13 case-matched healthy comparison subjects, a quantitative measure related to benzodiazepine receptor binding (distribution volume) was obtained with single photon emission computed tomography (SPECT) imaging of [(123)I]iomazenil binding and measurement of radioligand concentration in plasma. Distribution volume image data were analyzed by means of statistical parametric mapping.

RESULTS

Lower distribution volumes were found in the prefrontal cortex (Brodmann's area 9) of PTSD patients than in comparison subjects.

CONCLUSIONS

These findings of lower values for the benzodiazepine receptor binding measure of distribution volume are consistent with fewer benzodiazepine receptors and/or reduced affinity of receptor binding in the medial prefrontal cortex in patients with PTSD. Alterations in benzodiazepine receptor function in this area may underlie many of the symptoms of PTSD.

Neuroanatomic substrates of late-life mental disorders

Advances in magnetic resonance imaging (MRI) techniques have made it possible to quantify anatomic brain abnormalities in neuropsychiatric disorders. This review focuses on controlled, quantitative MRI studies in depression, degenerative disorders, and psychosis in the elderly. Although many of the anatomic abnormalities detected are observed across disorders, the patterns of regional involvement may be more selective and disorder specific. We integrate MRI findings with relevant clinical and neurobiologic observations in an attempt to develop a cohesive model of late-life psychiatric illness. Although the model primarily alludes to the pathophysiology of late-life depression, it may have broader biologic implications for other mental disorders in the elderly.

Low baseline and yohimbine-stimulated plasma neuropeptide Y (NPY) levels in combat-related PTSD

BACKGROUND

Consistent with many studies demonstrating enhanced reactivity of the sympathetic nervous system in posttraumatic stress disorder (PTSD), the administration of yohimbine, a noradrenergic alpha(2)-antagonist, has been shown to increase core symptoms of PTSD and to induce greater increases in plasma 3-methyl-4-hydroxy-phenyl-glycol (MHPG) in subjects with PTSD compared with healthy control subjects. In turn, neuropeptide Y (NPY) has been shown to inhibit the release of norepinephrine from sympathetic noradrenergic neurons.

METHODS

In the following study, plasma NPY responses to yohimbine and placebo were measured in a subgroup of 18 subjects with PTSD and 8 healthy control subjects who participated in the previous study of the effect of yohimbine on plasma MHPG.

RESULTS

The PTSD subjects had lower baseline plasma NPY and blunted yohimbine-stimulated increases in plasma NPY compared with the healthy control subjects. Within the PTSD group, baseline plasma NPY levels correlated negatively with combat exposure scale scores, baseline PTSD and panic symptoms, and yohimbine-stimulated increases in MHPG and systolic blood pressure.

CONCLUSIONS

This study suggests that combat stress-induced decreases in plasma NPY may mediate, in part, the noradrenergic system hyperreactivity observed in combat-related PTSD. The persistence of this decrease in plasma NPY may contribute to symptoms of hyperarousal and the expression of exaggerated alarm reactions, anxiety reactions, or both in combat veterans with PTSD long after war.

SPECT [I-123]iomazenil measurement of the benzodiazepine receptor in panic disorder

BACKGROUND

Alterations in benzodiazepine receptor function have long been hypothesized to play a role in anxiety. Animal models of anxiety involving exposure to chronic stress have shown a specific decrease in benzodiazepine receptor binding in frontal cortex and hippocampus. The purpose of this study was to examine benzodiazepine receptor binding patients with panic disorder and comparison subjects.

METHODS

A quantitative measure related to benzodiazepine receptor binding (Distribution Volume (DV)) was obtained with single photon emission computed tomography (SPECT) imaging of [123I]iomazenil and measurement of radioligand concentration in plasma in patients with panic disorder and healthy controls. DV image data were analyzed using statistical parametric mapping (spm96).

RESULTS

A decrease in measures of benzodiazepine receptor binding (DV) was found in left hippocampus and precuneus in panic disorder patients relative to controls. Panic disorder patients who had a panic attack compared to patients who did not have a panic attack at the time of the scan had a decrease in benzodiazepine receptor binding in prefrontal cortex.

CONCLUSIONS

Findings of a decrease in left hippocampal and precuneus benzodiazepine receptor binding may be related to alterations in benzodiazepine receptor binding, or other factors including changes in GABAergic transmission or possible endogenous benzodiazepine compounds. Benzodiazepine receptor function in prefrontal cortex appears to be involved in changes in state-related panic anxiety.

Kinetic modeling of benzodiazepine receptor binding with PET and high specific activity [(11)C]Iomazenil in healthy human subjects

Quantitation of the PET benzodiazepine receptor antagonist, [(11)C]Iomazenil, using low specific activity radioligand was recently described. The purpose of this study was to quantitate benzodiazepine receptor binding in human subjects using PET and high specific activity [(11)C]Iomazenil. Six healthy human subjects underwent PET imaging following a bolus injection of high specific activity (>100 Ci/mmol) [(11)C]iomazenil. Arterial samples were collected at multiple time points after injection for measurement of unmetabolized total and nonprotein-bound parent compound in plasma. Time activity curves of radioligand concentration in brain and plasma were analyzed using two and three compartment model. Kinetic rate constants of transfer of radioligand between plasma, nonspecifically bound brain tissue, and specifically bound brain tissue compartments were fitted to the model. Values for fitted kinetic rate constants were used in the calculation of measures of benzodiazepine receptor binding, including binding potential (the ratio of receptor density to affinity), and product of BP and the fraction of free nonprotein-bound parent compound (V(3)'). Use of the three compartment model improved the goodness of fit in comparison to the two compartment model. Values for kinetic rate constants and measures of benzodiazepine receptor binding, including BP and V(3)', were similar to results obtained with the SPECT radioligand [(123)I]iomazenil, and a prior report with low specific activity [(11)C]Iomazenil. Kinetic modeling using the three compartment model with PET and high specific activity [(11)C]Iomazenil provides a reliable measure of benzodiazepine receptor binding. Synapse 35:68-77, 2000. Published 2000 Wiley-Liss, Inc.

Hippocampal volume reduction in major depression

OBJECTIVE

Elevated levels of glucocorticoids in depression have been hypothesized to be associated with damage to the hippocampus, a brain area involved in learning and memory. The purpose of this study was to measure hippocampal volume in patients with depression.

METHOD

Magnetic resonance imaging was used to measure the volume of the hippocampus in 16 patients with major depression in remission and 16 case-matched nondepressed comparison subjects.

RESULTS

Patients with depression had a statistically significant 19% smaller left hippocampal volume than comparison subjects, without smaller volumes of comparison regions (amygdala, caudate, frontal lobe, and temporal lobe) or whole brain volume. The findings were significant after brain size, alcohol exposure, age, and education were controlled for.

CONCLUSIONS

These findings are consistent with smaller left hippocampal volume in depression.

Neural correlates of memories of childhood sexual abuse in women with and without posttraumatic stress disorder

OBJECTIVE

Childhood sexual abuse is very common in our society, but little is known about the long-term effects of abuse on brain function. The purpose of this study was to measure neural correlates of memories of childhood abuse in sexually abused women with and without the diagnosis of posttraumatic stress disorder (PTSD).

METHOD

Twenty-two women with a history of childhood sexual abuse underwent injection of [15O]H2O, followed by positron emission tomography imaging of the brain while they listened to neutral and traumatic (personalized childhood sexual abuse events) scripts. Brain blood flow during exposure to traumatic and neutral scripts was compared for sexually abused women with and without PTSD.

RESULTS

Memories of childhood sexual abuse were associated with greater increases in blood flow in portions of anterior prefrontal cortex (superior and middle frontal gyri-areas 6 and 9), posterior cingulate (area 31), and motor cortex in sexually abused women with PTSD than in sexually abused women without PTSD. Abuse memories were associated with alterations in blood flow in medial prefrontal cortex, with decreased blood flow in subcallosal gyrus (area 25), and a failure of activation in anterior cingulate (area 32). There was also decreased blood flow in right hippocampus, fusiform/inferior temporal gyrus, supramarginal gyrus, and visual association cortex in women with PTSD relative to women without PTSD.

CONCLUSIONS

These findings implicate dysfunction of medial prefrontal cortex (subcallosal gyrus and anterior cingulate), hippocampus, and visual association cortex in pathological memories of childhood abuse in women with PTSD. Increased activation in posterior cingulate and motor cortex was seen in women with PTSD. Dysfunction in these brain areas may underlie PTSD symptoms provoked by traumatic reminders in subjects with PTSD.

Role of norepinephrine in the pathophysiology and treatment of posttraumatic stress disorder

This review focuses on the role of norepinephrine (NE) in traumatic stress. The review is divided into three sections. The first section, "Norepinephrine and Arousal," describes preclinical studies related to norepinephrine's role in arousal, orienting to novel stimuli, selective attention and vigilance. It also contains a brief discussion of NE and its relationship to fear-provoking stimuli followed by preclinical and clinical studies that demonstrate heightened noradrenergic neuronal reactivity, increased alpha 2 receptor sensitivity and exaggerated arousal in organisms that have been exposed to chronic uncontrollable stress. The second section, "Norepinephrine and Memory," describes preclinical and clinical studies related to norepinephrine's role in enhanced encoding of memory for arousing and aversive events and in subsequent re-experiencing symptoms such as, intrusive memories and nightmares. The third section, "Norepinephrine and Pharmacologic Treatment," briefly discusses the use of adrenergic blockers, clonidine and propranol, as well as tricyclic and MAO inhibitors, for the treatment of PTSD. Finally, we attempt to synthesize trauma-related preclinical and clinical studies of norepinephrine. We do this, in part, by focusing on a series of yohimbine studies in subjects with PTSD because data from these studies allow for a discussion that brings together preclinical and clinical findings relevant to trauma-related alterations in arousal and memory.

Alterations in brain structure and function associated with post-traumatic stress disorder

Neuroimaging studies in post-traumatic stress disorder (PTSD) have revealed changes in brain structure and function that may underlie the symptoms of PTSD. Two brain areas that have been consistently implicated in PTSD include the hippocampus and prefrontal cortex. Several studies showed that PTSD is associated with reduction in volume of the hippocampus, a brain area involved in learning and memory, as measured with magnetic resonance imaging (MRI). Positron emission tomography (PET) studies showed dysfunction of medial and orbital prefrontal cortex during PTSD symptom provocation and in response to traumatic reminders. Decreased benzodiazepine receptor binding was found in the medial prefrontal cortex as measured with neuroimaging in PTSD. The hippocampus and medial prefrontal cortex play important roles in memory and emotional regulation, and dysfunction in these areas may underlie memory deficits and pathological emotions in PTSD.

Glutamate and post-traumatic stress disorder: toward a psychobiology of dissociation

Dissociative cognitive and perceptual alterations commonly occur at the time of traumatization and as an enduring feature of post-traumatic stress disorder (PTSD). After stress exposure, dissociative symptoms are a predictor of the development of PTSD. Recent preclinical data suggest that stress stimulates the cortico-limbic release of glutamate. The glutamate that is released during stress in animal models influences behavior, induces a variety of changes in neural plasticity that may have long-lasting effects on brain function and behavior, and contributes to neural toxicity. Antagonist of the N-methyl-D-aspartate (NMDA) subtype of glutamate receptor also stimulates transient cortico-limbic glutamate release in animals. Further, some of the effects of NMDA antagonists in animals are blocked by drugs that attenuate glutamate release. Clinical studies suggest that NMDA antagonists may transiently stimulate glutamate release and produce symptoms resembling dissociative states in humans. A recent study suggests that a drug that reduces glutamate release also attenuates the perceptual effects of the NMDA antagonist, ketamine, in humans. Because of the possible contributions of hyperglutamatergic states to the acute and long-lasting consequences of traumatic stress exposure, the therapeutic and neuroprotective potential of drugs that attenuate glutamate release should be explored in traumatized individuals with dissociative symptoms.

Neurotransmitter alterations in PTSD: catecholamines and serotonin

In this chapter we review trauma-related studies involving epinephrine (E), norepinephrine (NE), and serotonin (5-HT). Central catecholamine neurons seem to play a critical role in level of alertness, vigilance, orienting, selective attention, memory, fear conditioning, and cardiovascular responses to life-threatening stimuli. Evidence of catecholamine dysregulation in post-traumatic stress disorder (PTSD) includes exaggerated increases in heart rate and blood pressure when exposed to visual and auditory reminders of trauma, elevated 24-hour urine catecholamine excretion, decreased platelet alpha-2 adrenergic receptor number, exaggerated behavioral, cardiovascular, and biochemical responses to IY yohimbine, decreased cortical brain metabolism secondary to IV yohimbine, and clinical efficacy of adrenergic blocking agents. Serotonin seems to play numerous roles in the central nervous system, including regulation of sleep, aggression, appetite, cardiovascular and respiratory activity, motor output, anxiety, mood, neuroendocrine secretion, and analgesia. Evidence of serotonergic dysregulation in PTSD includes frequent symptoms of aggression, impulsivity, depression and suicidality, decreased platelet paroxetine binding, blunted prolactin response to fenfluramine, exaggerated reactivity to m-chloro-phenyl-piperazine, and clinical efficacy of serotonin reuptake inhibitors. It has been suggested that alterations in NE, E, and 5-HT may have relevance for symptoms commonly seen in survivors with PTSD, including hypervigilance, exaggerated startle, irritability, impulsivity, aggression, intrusive memories, depressed mood, and suicidality.

Quantitation of benzodiazepine receptor binding with PET [11C]iomazenil and SPECT [123I]iomazenil: preliminary results of a direct comparison in healthy human subjects

Although positron emission tomography (PET) and single photon emission computed tomography (SPECT) are increasingly used for quantitation of neuroreceptor binding, almost no studies to date have involved a direct comparison of the two. One study found a high level of agreement between the two techniques, although there was a systematic 30% increase in measures of benzodiazepine receptor binding in SPECT compared with PET. The purpose of the current study was to directly compare quantitation of benzodiazepine receptor binding in the same human subjects using PET and SPECT with high specific activity [11C]iomazenil and [123I]iomazenil, respectively. All subjects were administered a single bolus of high specific activity iomazenil labeled with 11C or 123I followed by dynamic PET or SPECT imaging of the brain. Arterial blood samples were obtained for measurement of metabolite-corrected radioligand in plasma. Compartmental modeling was used to fit values for kinetic rate constants of transfer of radioligand between plasma and brain compartments. These values were used for calculation of binding potential (BP = Bmax/Kd) and product of BP and the fraction of free non-protein-bound parent compound (V3'). Mean values for V3' in PET and SPECT were as follows: temporal cortex 23+/-5 and 22+/-3 ml/g, frontal cortex23+/-6 and 22+/-3 ml/g, occipital cortex 28+/-3 and 31+/-5 ml/g, and striatum 4+/-4 and 7+/-4 ml/g. These preliminary findings indicate that PET and SPECT provide comparable results in quantitation of neuroreceptor binding in the human brain.

Neural correlates of exposure to traumatic pictures and sound in Vietnam combat veterans with and without posttraumatic stress disorder: a positron emission tomography study

BACKGROUND

Patients with posttraumatic stress disorder (PTSD) show a reliable increase in PTSD symptoms and physiological reactivity following exposure to traumatic pictures and sounds. In this study neural correlates of exposure to traumatic pictures and sounds were measured in PTSD.

METHODS

Positron emission tomography and H2[15O] were used to measure cerebral blood flow during exposure to combat-related and neutral pictures and sounds in Vietnam combat veterans with and without PTSD.

RESULTS

Exposure to traumatic material in PTSD (but not non-PTSD) subjects resulted in a decrease in blood flow in medial prefrontal cortex (area 25), an area postulated to play a role in emotion through inhibition of amygdala responsiveness. Non-PTSD subjects activated anterior cingulate (area 24) to a greater degree than PTSD patients. There were also differences in cerebral blood flow response in areas involved in memory and visuospatial processing (and by extension response to threat), including posterior cingulate (area 23), precentral (motor) and inferior parietal cortex, and lingual gyrus. There was a pattern of increases in PTSD and decreases in non-PTSD subjects in these areas.

CONCLUSIONS

The findings suggest that functional alternations in specific cortical and subcortical brain areas involved in memory, visuospatial processing, and emotion underlie the symptoms of patients with PTSD.

Does stress damage the brain?

Studies in animals showed that stress results in damage to the hippocampus, a brain area involved in learning and memory, with associated memory deficits. The mechanism involves glucocorticoids and possibly serotonin acting through excitatory amino acids to mediate hippocampal atrophy. Patients with posttraumatic stress disorder (PTSD) from Vietnam combat and childhood abuse had deficits on neuropsychological measures that have been validated as probes of hippocampal function. In addition, magnetic resonance imaging (MRI) showed reduction in volume of the hippocampus in both combat veterans and victims of childhood abuse. In combat veterans, hippocampal volume reduction was correlated with deficits in verbal memory on neuropsychological testing. These studies introduce the possibility that experiences in the form of traumatic stressors can have long-term effects on the structure and function of the brain.

The effects of stress on memory and the hippocampus throughout the life cycle: implications for childhood development and aging

Studies in animals showing hippocampal atrophy and associated memory deficits in stress and aging have implications for stress and aging in humans. Clinical studies in traumatized human populations with posttraumatic stress disorder (PTSD) have replicated studies in animals, showing reduction in volume of the hippocampus measured with magnetic resonance imaging and associated memory deficits. Trauma at different stages of development (early childhood abuse versus trauma in later life due to combat) may influence the nature of memory deficits and hippocampal atrophy. Studies in aging human subjects are consistent with animal studies, although future research is needed in this area. The similarities between biological findings related to cortisol and the hippocampus in stress and aging in both animal and human studies raises the question of whether PTSD can be seen as a form of accelerated aging. Evidence that stress affects the hippocampus and the capacity for learning has broad implications for public health policy, underlying the need for additional resources in this important area and a reexamination of our understanding of factors influencing academic achievement.

Cerebral cortical hyperactivation in response to mental stress in patients with coronary artery disease

The central nervous system (CNS) effects of mental stress in patients with coronary artery disease (CAD) are unexplored. The present study used positron emission tomography (PET) to measure brain correlates of mental stress induced by an arithmetic serial subtraction task in CAD and healthy subjects. Mental stress resulted in hyperactivation in CAD patients compared with healthy subjects in several brain areas including the left parietal cortex [angular gyrus/parallel sulcus (area 39)], left anterior cingulate (area 32), right visual association cortex (area 18), left fusiform gyrus, and cerebellum. These same regions were activated within the CAD patient group during mental stress versus control conditions. In the group of healthy subjects, activation was significant only in the left inferior frontal gyrus during mental stress compared with counting control. Decreases in blood flow also were produced by mental stress in CAD versus healthy subjects in right thalamus (lateral dorsal, lateral posterior), right superior frontal gyrus (areas 32, 24, and 10), and right middle temporal gyrus (area 21) (in the region of the auditory association cortex). Of particular interest, a subgroup of CAD patients that developed painless myocardial ischemia during mental stress had hyperactivation in the left hippocampus and inferior parietal lobule (area 40), left middle (area 10) and superior frontal gyrus (area 8), temporal pole, and visual association cortex (area 18), and a concomitant decrease in activation observed in the anterior cingulate bilaterally, right middle and superior frontal gyri, and right visual association cortex (area 18) compared with CAD patients without myocardial ischemia. These findings demonstrate an exaggerated cerebral cortical response and exaggerated asymmetry to mental stress in individuals with CAD.

Safety of mirtazapine in overdose

INTRODUCTION

We report 6 confirmed cases of substantial overdose with mirtazapine, a new antidepressant compound, that occurred up to January 1997 in the United States during postmarketing surveillance or in the clinical trials.

RESULTS

In 6 patients, the mirtazapine doses ranged from 10 to 30 times the maximum recommended dose, and there were no serious adverse effects of overdose. Two patients at special risk, a 90-year-old man and a 3-year-old child, took higher-than-usual doses without serious sequelae. The 4 patients who combined other central nervous system (CNS) depressants with mirtazapine appeared to experience more CNS depression. One patient who ingested 60 mg of alprazolam had clinically significant respiratory depression in the emergency room but recovered fully within 24 hours.

CONCLUSION

After an overdose of substantial multiples of mirtazapine that exceed the maximum recommended daily dosage, the new antidepressant mirtazapine appears to be safe in a limited number of cases.

Interactive effects of subanesthetic ketamine and subhypnotic lorazepam in humans

Ketamine is an N-methyl-D-aspartate (NMDA) receptor antagonist with psychotogenic and dissociative effects in healthy humans. These cognitive and perceptual effects in humans are reportedly reduced by benzodiazepine premedication. This study assessed the interactive effects of a ketamine (i.v. bolus of 0.26 mg/kg followed by an infusion of 0.65 mg/kg per hour) and lorazepam 2 mg., PO, in humans. Twenty-three healthy subjects completed 4 test days involving the oral administration of lorazepam or matched placebo 2 h prior to the i.v. infusion of ketamine or placebo. Ketamine: 1) produced behaviors similar to the positive and negative symptoms of schizophrenia as assessed by the Brief Psychiatric Rating Scale (BPRS); 2) evoked perceptual alterations as measured by the Clinician-Administered Dissociative States Scale (CADSS); 3) impaired performance on the Wisconsin Card Sorting Test (WCST) and other tests sensitive to frontal cortical impairment; and 4) had amnestic effects. Lorazepam produced attention impairments, concrete proverb interpretations, and recall impairments. Lorazepam reduced ketamine-associated emotional distress and there was a non-significant trend for it to decrease perceptual alterations produced by ketamine. However, it failed to reduce many cognitive and behavioral effects of ketamine, including psychosis. Further, lorazepam exacerbated the sedative, attention-impairing, and amnestic effects of ketamine. There was no evidence of pharmacokinetic interaction between these medications. These data suggest that subhypnotic lorazepam and ketamine show a spectrum of interactive effects, ranging from antagonism to potentiation.

Measurement of dissociative states with the Clinician-Administered Dissociative States Scale (CADSS)

The purpose of this study was to develop an instrument for the measurement of present-state dissociative symptoms, the Clinician Administered Dissociative States Scale (CADSS). Reported here are interrater reliability and internal consistency of the CADSS, validity as assessed by comparisons with other instruments for the assessment of dissociation, and sensitivity of the CADSS to discriminate patients with dissociative disorders from patients with other psychiatric disorders and healthy subjects. Initial analyses indicated good interrater reliability and construct validity for the CADSS. Scores on the CADSS discriminated patients with dissociative disorders from the other groups.

Noradrenergic and serotonergic function in posttraumatic stress disorder

BACKGROUND

Yohimbine hydrochloride produces marked behavioral and cardiovascular effects in combat veterans with posttraumatic stress disorder (PTSD). In the present study, yohimbine was used as a probe of noradrenergic activity, and meta-chlorophenylpiperazine (m-CPP) as a probe of serotonergic activity. To our knowledge, this is the first study to describe the behavioral and cardiovascular effects of meta-CPP in patients with PTSD, and to compare these effects with those of yohimbine.

METHOD

Twenty-six patients with PTSD and 14 healthy subjects each received an intravenous infusion of yohimbine hydrochloride (0.4 mg/kg), m-CPP (1.0 mg/kg), or saline solution on 3 separate test days in a randomized balanced order and in double-blind fashion. Behavioral and cardiovascular measurements were determined at multiple times.

RESULTS

Eleven (42%) of the patients with PTSD experienced yohimbine-induced panic attacks and had significantly greater increases compared with controls in anxiety, panic, and PTSD symptoms, but not in cardiovascular measurements. Eight patients (31%) with PTSD experienced m-CPP-induced panic attacks and had significantly greater increases compared with controls in anxiety, panic, and PTSD symptoms, and in standing diastolic blood pressure. Yohimbine-induced panic attacks tended to occur in different patients from m-CPP-induced panic attacks.

CONCLUSION

These data suggest the presence of 2 neurobiological subgroups of patients with PTSD, one with a sensitized noradrenergic system, and the other with a sensitized serotonergic system.

Elevated CSF corticotropin-releasing factor concentrations in posttraumatic stress disorder

OBJECTIVE

Corticotropin-releasing factor (CRF) and somatostatin both play important roles in mediating responses to acute and chronic stress. The purpose of this study was to measure CSF concentrations of CRF and somatostatin in patients with chronic combat-related post-traumatic stress disorder (PTSD) and comparison subjects.

METHOD

Lumbar punctures for collection of CSF were performed in Vietnam combat veterans with PTSD (N = 11) and comparison subjects (N = 17). CSF concentrations of CRF and somatostatin were compared between the two groups.

RESULTS

CSF concentrations of CRF were higher in the PTSD patients than in the comparison subjects (mean = 29.0 pg/ml, SD = 7.8, versus mean = 21.9 pg/ml, SD = 6.0). This group difference remained significant after covariance for age. CSF somatostatin concentrations in PTSD patients were higher than those of the comparison subjects (mean = 19.9 pg/ml, SD = 5.4, versus mean = 13.7 pg/ml, SD = 8.0). However, covarying for age reduced the level of significance.

CONCLUSIONS

Higher CSF CRF concentrations in patients with PTSD may reflect alterations in stress-related neurotransmitter systems. The higher CSF CRF concentrations may play a role in disturbances of arousal in patients with PTSD.

Scholastic impairments among traumatized adolescents

This investigation sought to determine if exposure to exceptional stress is associated with academic deficits or whether academic deficits are specifically associated with post-traumatic stress disorder (PTSD). In order to address these questions, the Metropolitan Achievement Test (MAT) as well as a measure of intelligence were administered to three groups of Lebanese adolescents. The first group met diagnostic criteria for PTSD. The second group had been exposed to qualitatively and quantitatively similar stressors but did not meet diagnostic criteria for PTSD. The third group consisted of nontraumatized controls. Data analysis using IQ as a covariate determined that the MAT scores of the PTSD subjects were significantly lower than the scores of the stress exposed PTSD negatives and controls. No significant differences were observed when the MAT scores of the stress exposed PTSD negatives and controls were compared.

Positron emission tomography measurement of cerebral metabolic correlates of tryptophan depletion-induced depressive relapse

BACKGROUND

Short-term depletion of plasma tryptophan has been shown to result in depressive relapse in patients with remission of major depression. Positron emission tomography and single photon emission computed tomography studies implicated the dorsolateral prefrontal cortex, orbitofrontal cortex, thalamus, and caudate nucleus in the pathogenesis of depression. The purpose of this study was to measure cerebral metabolic correlates of tryptophan depletion-induced depressive relapse.

METHODS

Patients diagnosed as having major depression (N = 21) who clinically improved with serotonin reuptake inhibitors underwent 2 test days involving tryptophan depletion or placebo, followed 6 hours later by positron emission tomography scanning with fludeoxy-glucose F18. Brain metabolism was compared in patients with (n = 7) and without (n = 14) a tryptophan depletion-induced depressive relapse.

RESULTS

Tryptophan depletion resulted in a decrease in brain metabolism in the middle frontal gyrus (dorsolateral prefrontal cortex), thalamus, and orbitofrontal cortex in patients with a depletion-induced depressive relapse (but not in patients without depletion-induced relapse). Decreased brain metabolism in these regions correlated with increased depressive symptoms. Baseline metabolism was increased in prefrontal and limbic regions in relapse-prone patients.

CONCLUSION

Specific brain regions, including the middle frontal gyrus, thalamus, and orbitofrontal cortex, may mediate the symptoms of patients with major depression.

Positron emission tomography measurement of cerebral metabolic correlates of yohimbine administration in combat-related posttraumatic stress disorder

BACKGROUND

We have previously reported an increase in symptoms of anxiety in patients with posttraumatic stress disorder (PTSD) following administration of the beta 2-antagonist yohimbine, which stimulates brain norepinephrine release. Preclinical studies show decreased metabolism in the neocortex and the caudate nucleus with high-dose yohimbine-induced norepinephrine release, but low levels of norepinephrine release result in an increase in metabolism in these areas.

METHODS

We used positron emission tomography and fludeoxyglucose F 18 to measure brain metabolism in Vietnam combat veterans with PTSD (n = 10) and healthy age-matched control subjects (n = 10), following administration of yohimbine (0.4 mg/kg) or placebo in a randomized, double-blind fashion.

RESULTS

Yohimbine resulted in a significant increase in anxiety in the patients with PTSD, but not in healthy subjects. There was a significant difference in brain metabolic response to yohimbine in patients with PTSD compared with healthy subjects in prefrontal, temporal, parietal, and orbitofrontal cortexes. Metabolism tended to decrease in patients with PTSD and increase in healthy subjects following administration of yohimbine.

CONCLUSION

These findings are consistent with our previous hypothesis of enhanced norepinephrine release in the brain with yohimbine in patients with PTSD.

Magnetic resonance imaging-based measurement of hippocampal volume in posttraumatic stress disorder related to childhood physical and sexual abuse--a preliminary report

We have previously reported smaller hippocampal volume and deficits in short-term memory in patients with combat-related posttraumatic stress disorder (PTSD) relative to comparison subjects. The purpose of this study was to compare hippocampal volume in adult survivors of childhood abuse to matched controls. Magnetic resonance imaging was used to measure volume of the hippocampus in adult survivors of childhood abuse (n = 17) and healthy subjects (n = 17) matched on a case-by-case basis for age, sex, race, handedness, years of education, body size, and years of alcohol abuse. All patients met criteria for PTSD secondary to childhood abuse. PTSD patients had a 12% smaller left hippocampal volume relative to the matched controls (p < .05), without smaller volumes of comparison regions (amygdala, caudate, and temporal lobe). The findings were significant after controlling for alcohol, age, and education, with multiple linear regression. These findings suggest that a decrease in left hippocampal volume is associated with abuse-related PTSD.

Trauma-related dissociative states and long-term psychopathology in posttraumatic stress disorder

Dissociative responses to trauma have been hypothesized to be associated with long-term increases in psychopathology. The purpose of this study was to examine dissociative responses to premilitary, combat-related and postmilitary traumatic events and long-term psychopathology in Vietnam combat veterans with (n = 34) and without (n = 28) posttraumatic stress disorder (PTSD). PTSD patients reported higher levels of dissociative states at the time of combat-related traumatic events than non-PTSD patients. Higher levels of dissociative states persisted in PTSD patients in the form of higher levels of dissociative states in-response to postmilitary traumatic events. In addition, dissociative responses to combat trauma were associated with higher long-term general dissociative symptomatology as measured by scores on the Dissociative Experience Scale, as well as increases in the number of flashbacks since the time of the war. These findings are consistent with previous formulations that dissociation in the face of trauma is a marker of long-term psychopathology.

Neural mechanisms in dissociative amnesia for childhood abuse: relevance to the current controversy surrounding the "false memory syndrome"

OBJECTIVE

There is considerable controversy about delayed recall of childhood abuse. Some authors have claimed that there is a "false memory syndrome," in which therapists suggest to patients events that never actually occurred. These authors point to findings that suggest that memory traces are susceptible to modification. The purpose of this paper is to review the literature on the potential vulnerability of memory traces to modification and on the effects of stress on the neurobiology of memory.

METHOD

The authors review findings on mechanisms involved in normal memory function, effects of stress on memory in normal persons, children's memory of stressful events, and alterations of memory function in psychiatric disorders. The effects of stress on specific brain regions and brain chemistry are also examined.

RESULTS

Neuropeptides and neurotransmitters released during stress can modulate memory function, acting at the level of the hippocampus, amygdala, and other brain regions involved in memory. Such release may interfere with the laying down of memory traces for incidents of childhood abuse. Also, childhood abuse may result in long-term alterations in the function of these neuromodulators.

CONCLUSIONS

John Nemiah pointed out several years ago that alterations in memory in the form of dissociative amnesia are an important part of exposure to traumatic stressors, such as childhood abuse. The studies reviewed here show that extreme stress has long-term effects on memory. These findings may provide a model for understanding the mechanisms involved in dissociative amnesia, as well as a rationale for phenomena such as delayed recall of childhood abuse.

Noradrenergic mechanisms in stress and anxiety: I. Preclinical studies

There is considerable preclinical evidence for a relationship between noradrenergic brain systems and behaviors associated with stress and anxiety. The majority of noradrenergic neurons are located in the locus coeruleus (pons), with projections throughout the cerebral cortex and multiple subcortical areas, including hippocampus, amygdala, thalamus, and hypothalamus. This neuroanatomical formation of the noradrenergic system makes it well suited to rapidly and globally modulate brain function in response to changes in the environment, as occurs during the presentation of stressors. Stress exposure is associated with an increase in firing of the locus coeruleus and with associated increased release and turnover of norepinephrine in brain regions which receive noradrenergic innervation. Increased firing of the locus coeruleus is also associated with behavioral manifestations of fear, such as arched back and piloerection in the cat. Exposure to chronic stress results in long-term alterations in locus coeruleus firing and norepinephrine release in target brain regions of the locus coeruleus. Norepinephrine is also involved in neural mechanisms such as sensitization and fear conditioning, which are associated with stress. These findings are relevant to an understanding of psychiatric disorders, such as panic disorder and post-traumatic stress disorder (PTSD), the symptoms of which have been hypothesized to be related to alterations in noradrenergic function.

Noradrenergic mechanisms in stress and anxiety: II. Clinical studies

Studies in animals have shown a relationship between alterations in noradrenergic brain system function and behaviors of anxiety and fear. These findings have generated the hypothesis that the symptoms seen in patients with anxiety disorders may be related to alterations in noradrenergic function. A number of clinical studies have tested this hypothesis, utilizing measures of catecholaminergic function such as heart rate and blood pressure, measurement of norepinephrine and its metabolites in urine and plasma and adrenergic receptor binding in platelets, as well as pharmacological challenge to the noradrenergic system. Acute stressors, such as public speaking, have been associated with an increase in heart rate, blood pressure, and norepinephrine and its metabolites in urine and plasma. Findings in patients with panic disorder at baseline related to heart rate, blood pressure, baseline norepinephrine and its metabolites, and platelet adrenergic receptors have been mixed, while the most consistent findings have been blunted growth hormone response to clonidine and increased 3-methoxy-4-hydroxy-phenylethylene-glucol (MHPG) and anxiety following stimulation of the noradrenergic system with yohimbine. Baseline measures of noradrenergic function in patients with posttraumatic stress disorder (PTSD) have also been mixed, while an increased heart, blood pressure and norepinephrine response to traumatic reminders, as well as increased behavioral (as well as different brain metabolic) response to yohimbine, have been found in PTSD. There are fewer studies of noradrenergic function in the other anxiety disorders, and the findings there have not been consistent. These studies provide evidence for increased noradrenergic responsiveness in panic disorder and PTSD, although there does not appear to be an alteration in baseline noradrenergic function in these patients.

Chronic PTSD in Vietnam combat veterans: course of illness and substance abuse

OBJECTIVE

The purpose of this study was to measure the longitudinal course of specific symptoms of posttraumatic stress disorder (PTSD) and related symptoms of alcohol and substance abuse and the effects of alcohol and substances on the symptoms of PTSD.

METHOD

A structured interview for the assessment of PTSD and alcohol and substance abuse, as well as other factors such as life stressors and treatment, was administered to 61 Vietnam combat veterans with PTSD.

RESULTS

Onset of symptoms typically occurred at the time of exposure to combat trauma in Vietnam and increased rapidly during the first few years after the war. Symptoms plateaued within a few years after the war, following which the disorder became chronic and unremitting. Hyperarousal symptoms such as feeling on guard and feeling easily startled developed first, followed by avoidant symptoms and finally by symptoms from the intrusive cluster. The onset of alcohol and substance abuse typically was associated with the onset of symptoms of PTSD, and the increase in use paralleled the increase of symptoms. Patients reported a tendency for alcohol, marijuana, heroin, and benzodiazepines to make PTSD symptoms better, while cocaine made symptoms in the hyperarousal category worse. There was no relationship between treatment interventions and the natural course of PTSD.

CONCLUSIONS

These findings suggest that symptoms of PTSD begin soon after exposure to trauma, that hyperarousal symptoms are the first symptoms to occur, that the natural course of alcohol and substance abuse parallels that of PTSD, and that specific substances have specific effects on PTSD symptoms.

Deficits in short-term memory in adult survivors of childhood abuse

Exposure to stress has been associated with alterations in memory function, and we have previously shown deficits in short-term verbal memory in patients with a history of exposure to the stress of combat and the diagnosis of posttraumatic stress disorder (PTSD). Few studies of any kind have focused on adult survivors of childhood physical and sexual abuse. The purpose of this study was to investigate short-term memory function in adult survivors of childhood abuse. Adult survivors of severe childhood physical and sexual abuse (n = 21), as defined by specific criteria derived from the Early Trauma Inventory (ETI), who were presenting for psychiatric treatment were compared with healthy subjects (n = 20) matched for several variables including age, alcohol abuse, and years of education. All subjects were assessed with the Wechsler Memory Scale (WMS) Logical (verbal memory) and Figural (visual memory) components, the Verbal and Visual Selective Reminding Tests (SRT), and the Wechsler Adult Intelligence Scale-Revised (WAIS-R). Adult survivors of childhood abuse had significantly lower scores on the WMS Logical component for immediate and delayed recall in comparison to normal subjects, with no difference in visual memory, as measured by the WMS or the SRT, or IQ, as measured by the WAIS-R. Deficits in verbal memory, as measured by the WMS, were associated with the severity of abuse, as measured by a composite score on the ETI. Our findings suggest that childhood physical and sexual abuse is associated with long-term deficits in verbal short-term memory. These findings of specific deficits in verbal (and not visual) memory, with no change in IQ, are similar to the pattern of deficits that we have previously found in patients with combat-related PTSD.