Psychoneuroendocrine assessment of posttraumatic stress disorder: current progress and new directions

Exposure to war and conflict: The individual and inherited epigenetic effects on health, with a focus on post-traumatic stress disorder

War and conflict are global phenomena, identified as stress-inducing triggers for epigenetic modifications. In this state-of-the-science narrative review based on systematic principles, we summarise existing data to explore the outcomes of these exposures especially in veterans and show that they may result in an increased likelihood of developing gastrointestinal, auditory, metabolic and circadian issues, as well as post-traumatic stress disorder (PTSD). We also note that, despite a potential "healthy soldier effect", both veterans and civilians with PTSD exhibit the altered DNA methylation status in hypothalamic-pituitary-adrenal (HPA) axis regulatory genes such as NR3C1. Genes associated with sleep (PAX8; LHX1) are seen to be differentially methylated in veterans. A limited number of studies also revealed hereditary effects of war exposure across groups: decreased cortisol levels and a heightened (sex-linked) mortality risk in offspring. Future large-scale studies further identifying the heritable risks of war, as well as any potential differences between military and civilian populations, would be valuable to inform future healthcare directives.

Time-dependent protective effects of morphine against behavioral and morphological deficits in an animal model of posttraumatic stress disorder

Post-traumatic stress disorder (PTSD) arises after an individual has experienced a major traumatic event. Recent evidence suggests that acute morphine treatment may serve as a strategy to reduce PTSD development. In the present study, we investigated the time-dependent effects of morphine on behavioral and morphological deficits induced by the single prolonged stress (SPS), an experimental model of PTSD, in adult male rats. The rats were exposed to SPS (restraint for 2 h, forced swimming for 20 min, and ether anesthesia), and kept undistributed for 11 days. Morphine was injected immediately, 6, 12 and 24 h after SPS. Anxiety profile was evaluated using the elevated plus maze11 days after SPS. Then, animals were conditioned in a fear conditioning task and extinction training was performed on days 1, 2, 3, 4 and 11 after fear conditioning which followed by morphological assessments in the medial prefrontal cortex (mPFC). SPS rats showed increased anxiety levels and impaired contextual fear extinction retention. SPS also decreased dendritic length in the infra-limbic (IL) and dendritic spines in the IL and pre-limbic (PL) regions of the mPFC. Conversely, morphine treatment 6, 12 and 24 h but not immediately after SPS significantly improved anxiety-like behaviors, fear extinction, increased dendritic length, and spines in the mPFC. Morphine-induced much stronger response when injected 24 h after the SPS, and this effect was blocked by naloxone. Our findings show that morphine within a restricted time window selectively reversed the SPS-induced deficits in anxiety profile, fear extinction, and dendritic morphology in the mPFC. Finally, these findings suggest that the time point of morphine injection following a traumatic event is an important determinant of the full therapeutic effect of morphine against PTSD.

The effect of chronic phenytoin administration on single prolonged stress induced extinction retention deficits and glucocorticoid upregulation in the rat medial prefrontal cortex

RATIONALE

Post-traumatic stress disorder (PTSD) is a chronic, debilitating disorder. Only two pharmacological agents are approved for PTSD treatment, and they often do not address the full range of symptoms nor are they equally effective in all cases. Animal models of PTSD are critical for understanding the neurobiology involved and for identification of novel therapeutic targets. Using the rodent PTSD model, single prolonged stress (SPS), we have implicated aberrant excitatory neural transmission and glucocorticoid receptor (GR) upregulation in the medial prefrontal cortex (mPFC) and hippocampus (HPC) in fear memory abnormalities associated with PTSD.

OBJECTIVE

The objective of this study is to examine the potential protective effect of antiepileptic phenytoin (PHE) administration on SPS-induced extinction retention deficits and GR expression.

METHODS

Forty-eight SPS-treated male Sprague Dawley rats or controls were administered PHE (40, 20 mg/kg, vehicle) for 7 days following SPS stressors; then, fear conditioning, extinction, and extinction retention were tested.

RESULTS

Fear conditioning and extinction were unaffected by SPS or PHE, but SPS impaired extinction retention, and both doses of PHE rescued this impairment. Similarly, SPS increased GR expression in the mPFC and dorsal HPC, and PHE prevented SPS-induced GR upregulation in the mPFC.

CONCLUSIONS

These data demonstrate that PHE administration can prevent the development of extinction retention deficits and upregulation of GR. PHE exerts inhibitory effects on voltage-gated sodium channels and decreases excitatory neural transmission via glutamate antagonism. If glutamate hyperactivity in the days following SPS contributes to SPS-induced deficits, then these data may suggest that the glutamatergic system constitutes a target for secondary prevention.

Posttraumatic stress disorder and suicide risk among veterans: a literature review

Posttraumatic stress disorder (PTSD) is frequently associated with suicidal ideation and suicide attempts. Suicide is an important cause of death in veterans, and the risk for intentional death continues to be high many years after service. The aim of the present study was to investigate whether there is a relationship between PTSD and suicidal behavior among veterans. We also discussed the risk factors of suicide among war veterans with PTSD. A systematic review was conducted focusing on war-related PTSD and suicidal behavior. A total of 80 articles from peer-reviewed journals were identified, 34 were assessed for eligibility, and 16 were included. Having a history of PTSD is associated with higher rates of morbidity and mortality and increased the risk for suicidal behavior. The association between PTSD and suicidal behavior was confirmed by the presence of other risk factors and high rates of comorbidity. Current suicidal behavior should be adequately assessed in war veterans.

Altered locus coeruleus-norepinephrine function following single prolonged stress

Data from preclinical and clinical studies have implicated the norepinephrine system in the development and maintenance of post-traumatic stress disorder. The primary source of norepinephrine in the forebrain is the locus coeruleus (LC); however, LC activity cannot be directly measured in humans, and previous research has often relied upon peripheral measures of norepinephrine to infer changes in central LC-norepinephrine function. To directly assess LC-norepinephrine function, we measured single-unit activity of LC neurons in a validated rat model of post-traumatic stress disorder - single prolonged stress (SPS). We also examined tyrosine hydroxylase mRNA levels in the LC of SPS and control rats as an index of norepinephrine utilisation. For electrophysiological recordings, 92 LC neurons were identified from 19 rats (SPS, 12; control, 7), and spontaneous and evoked responses to a noxious event (paw compression) were recorded. Baseline and restraint stress-evoked tyrosine hydroxylase mRNA expression levels were measured in SPS and control rats (n = 16 per group) in a separate experiment. SPS rats showed lower spontaneous activity but higher evoked responses, leading to an enhanced signal-to-noise ratio of LC neurons, accompanied by impaired recovery from post-stimulus inhibition. In concert, tyrosine hydroxylase mRNA expression in the LC of SPS rats tended to be lower at baseline, but was exaggerated following restraint stress. These data demonstrate persistent changes in LC function following stress/trauma in a rat model of post-traumatic stress, as measured by differences in both the electrophysiological properties of LC neurons and tyrosine hydroxylase mRNA transcription.

[Psychoneuroendocrinology of posttraumatic stress disorder]

OBJECTIVE

To review the literature on neurobiological findings related to hypothalamic-pituitary-adrenal axis dysfunctions associated with posttraumatic stress disorder.

METHOD

The relevant scientific findings were described according to the date of publication and the characteristics of the studies: preclinical studies, studies on early life violence as a risk factor, and clinical findings related to patients diagnosed with posttraumatic stress disorder.

RESULTS

A rich literature on hypothalamic-pituitary-adrenal axis dysfunctions and posttraumatic stress disorder was found. Neurobiological findings showed that posttraumatic stress disorder is associated with hypothalamic-pituitary-adrenal axis dysfunctions and other brain-related structures: prefrontal cortex, hippocampus, and amygdala. Posttraumatic stress disorder patients have low plasma levels of cortisol and present increased responsivity of glucocorticoid receptors, suggesting that the inhibition of negative feedback plays a significant role in the disorder pathology. Preclinical studies using animal models of maternal deprivation showed that depending on the moment the trauma occurred during the development, different hypothalamic-pituitary-adrenal axis dysfunctions were produced. Clinical studies showed that early life stress is related to the development of psychopathologies during adulthood.

CONCLUSIONS

There is robust evidence of hypothalamic-pituitary-adrenal axis dysfunctions related to posttraumatic stress disorder, and the mechanisms underlying this association are being better understood.

Crossroads of corticotropin releasing hormone, corticosteroids and monoamines. About a biological interface between stress and depression

Mental disorders are frequently preceded by stressful events or situations. Depression is a typical case in point. This raises the question, is depression - or possibly better: are certain forms of depression - caused by stress? Can stress be a true pathogenic factor? Phrased differently: can stress destabilize neuronal systems in the central nervous system to such an extent that depressive symptoms are generated? This question is discussed with the corticotrophin releasing hormone (CRH) and MA systems and hypothalamic-pituitary-adrenal (HPA) axis as major foci. The following issues are explored: the effect of antidepressants on corticosteroid receptor gene expression; the behavioral sequellae of CRH administration; CRH disturbances in depression; the impact of early life adversity on the development of the CRH system and on stress reactivity; the interrelationships of stress hormones and monoaminergic (MA ergic) transmission and finally the therapeutic potential of CRH and cortisol antagonists. The available data suggest that CRH overdrive and cortisol overproduction may play a pathogenic role in the occurrence of certain types of depression, directly and/or indirectly, i.e. by induction or exacerbation of disturbances in MA ergic transmission. Stress should, thus, become a major focus of biological depression research.

Corticotropin-releasing hormone in depression and post-traumatic stress disorder

Corticotropin-releasing hormone (CRH) has been implicated in the regulation of a wide range of behaviors including arousal, motor function, feeding, and reproduction. Because depressed patients are often hypercortisolemic and intracerebroventricular administration of CRH to experimental animals produces a syndrome reminiscent of depression, dysregulation of this compound has been suggested to be involved in the pathogenesis of depressive and anxiety disorders. Studies of cerebrospinal fluid CRH levels and clinical neuroendocrine tests in patients with anxiety and affective disorders have supported this hypothesis. This review discusses these neuroendocrine findings in melancholic and atypical depression as well as post-traumatic stress disorder (PTSD). Overall, the data suggest that melancholic depression is characterized by hyperactive central CRH systems with overactivity of the pituitary-adrenal (HPA) axis. On the other hand, atypical depression is characterized by hypoactive central CRH systems and accompanying underactivity of the hypothalamic-pituitary-adrenal axis. Furthermore, the neuroendocrinology of PTSD appears to be unique, in that patients have hyperactive central CRH systems with underactivity of the pituitary-adrenal axis.

Anxiety disorders: a review of tricyclic antidepressants and selective serotonin reuptake inhibitors

OBJECTIVE

Anxiety disorders are the most common mental health disorders. While the older tricylic antidepressants (TCAs) are efficacious in the treatment of many anxiety disorders, recent studies with fluoxetine and other selective serotonin reuptake inhibitors (SSRIs) have emphasized the role of serotonin in the aetiology of these conditions.

METHOD

We reviewed the efficacy, safety and tolerability of TCAs and SSRIs in the treatment of the most common anxiety disorders, specifically, panic disorder, obsessive-compulsive disorder, post-traumatic stress disorder, social phobia and generalized anxiety disorder.

RESULTS

Both the TCA and SSRI antidepressants are effective in treating a wide variety of anxiety disorders. SSRIs, due to their greater safety and tolerability, should be the preferred choices in treating anxiety disorders in those instances where TCAs and SSRIs are considered equally effective. In the cases of OCD and social phobia, SSRIs are almost always preferable given that the TCAs do not appear effective in these disorders.

CONCLUSION

Further research is needed on the naturalistic long-term use of the TCAs and SSRIs in the treatment of anxiety disorders.

Immune, endocrine, and psychological responses in civilians displaced by war

OBJECTIVES

The objectives of this study were to assess the influence of trauma caused by forced expulsion from home in a war-ravaged region on the psychological, hormonal, and immune responses in displaced persons and to analyze the relationships between psychometric, hormonal, and immunologic variables.

METHODS

Participants were 20 displaced and 14 control women. Psychosomatic response was evaluated using the COR-NEX2 test. Serum concentrations of cortisol, prolactin, endorphin, thyroxine, and triiodothyronine were measured by radioimmunoassay. Immunophenotyping and lymphocyte proliferation were determined by flow cytometry, and phagocyte functions (i.e., ingestion and antibody-dependent cytotoxicity) against 51Cr-labeled sheep red blood cells were assessed through radioactivity uptake and release, respectively.

RESULTS

In comparison with control women, displaced women had higher COR-NEX2 test scores; higher serum cortisol, prolactin, and endorphin levels; an increase in activated phenotype within all three measured cell populations (i.e., B, T, and natural killer cells); as well as an enhanced proportion of proliferating lymphocytes in freshly isolated samples. However, the phytohemagglutinin-stimulated proliferative response, estimated as the stimulation index, was lower in displaced women. A complex pattern of relations between psychological, hormonal, and immune responses was observed.

CONCLUSIONS

Chronic psychological stress elicited multiple, predominantly stimulatory influences on immune functions.

Brain activation in PTSD in response to trauma-related stimuli

BACKGROUND

Repetitive recall of traumatic memories and chronic intermittent hyperarousal are characteristic of posttraumatic stress disorder (PTSD). Hyperarousal and memory dysfunction implicates "limbic" brain regions, including the amygdaloid complex, hippocampal formation, and limbic cortex, such as the orbitofrontal and anterior cingulate areas. To investigate the neurobiologic role of these brain regions in PTSD, we measured regional cerebral blood flow in PTSD with single photon emission computerized tomography (SPECT) during a symptom provocation paradigm.

METHODS

Fourteen Vietnam veterans with PTSD, 11 combat control subjects, and 14 normal control subjects were studied with [99mTc]HMPAO in two sessions 48 hours apart: one session after exposure to white noise and the other following exposure to combat sounds. Skin conductance, heart rate, and subjective experience were recorded at the time of the studies.

RESULTS

Activation for all three groups occurred in the anterior cingulate/middle prefrontal gyrus. Activation in the region of the left amygdala/nucleus accumbens was found in PTSD patients only. Deactivation was found in all three groups in the left retrosplenial region.

CONCLUSIONS

These findings implicate regions of the "limbic" brain, which may mediate the response to aversive stimuli in healthy individuals and in patients suffering from PTSD.

Burnout, perceived stress, and cortisol responses to awakening

OBJECTIVE

The effects of burnout and perceived stress on early morning free cortisol levels after awakening were investigated in a group of teachers. Previous studies revealed that cortisol levels show a significant increase after awakening, with high intraindividual stability.

METHODS

Sixty-six teachers from local public schools (42 women and 24 men, mean age 42+/-5 years) were asked to sample saliva for cortisol analysis on 3 consecutive days. On each day, cortisol levels were measured at the time of awakening and 15, 30, and 60 minutes thereafter. On the night before the third day, subjects took 0.5 mg dexamethasone orally for testing glucocorticoid feedback inhibition. Burnout and perceived stress were measured by three different questionnaires.

RESULTS

Perceived stress correlated with increases of cortisol levels during the first hour after awakening after dexamethasone pretreatment. In addition, teachers scoring high on burnout showed lower overall cortisol secretion on all sampling days, and a higher suppression of cortisol secretion after dexamethasone administration. In the subgroup of teachers with both high levels of perceived stress and high levels of burnout, a lower overall cortisol secretion was observed on the first 2 days, with stronger increases during the first hour after awakening after dexamethasone suppression. This subgroup also showed the lowest self-esteem, the highest external locus of control, and the highest number of somatic complaints.

CONCLUSIONS

These results demonstrate differential effects of burnout and perceived stress on hypothalamic-pituitary-adrenal axis regulation.

Post-traumatic stress disorder in children and adolescents exposed to violence

The common biopsychosocial sequelae of violence exposures are reviewed, with a focus on post-traumatic stress disorder in developmental, clinical, and familial contexts. Challenges to assessment are reviewed, and implications for prevention and treatment are presented. Pediatricians have an essential role to play in secondary and tertiary prevention through the use of anticipatory guidance and victimization as a marker of developmental risk.

Increasing correlations between personality traits and cortisol stress responses obtained by data aggregation

Attempts to link personality traits and cortisol stress responses have often been inconclusive. The aim of this paper was to investigate this association by aggregating cortisol stress responses. Therefore, 20 healthy men were exposed to a task consisting of public speaking and mental arithmetics in front of an audience on five days. Six cortisol levels were measured in relation to the stressful task obtained at 10-min intervals on each day. Psychological assessment included the Questionnaire for Competence and Control (FKK) and the Giessen-Test (G-T). These questionnaires focus on assessing personality traits, i.e. locus of control and self-concept. Areas under the response curve (AUC) of the six cortisol samples were computed to obtain an index of the individual's cortisol stress response on each day. Since novelty is a random situational factor likely to mask individual differences in the stress response, the AUC cortisol stress responses of days two to five were consecutively aggregated, excluding the first day. Scales of the two questionnaires employed did not correlate with the AUC cortisol stress response of the first stress trial. The correlation pattern of the AUC cortisol measures of days two to five with the questionnaire scales was inconclusive. However, significant correlations emerged with an increasing number of cortisol stress responses aggregated. Correlations between the measure of social dominance and aggregated AUC cortisol stress responses rose from r = -.47 on day two of the experimental session to r = -.70 after aggregating days two to five. Similarly, measures of locus of control and cortisol stress responses became increasingly correlated with aggregation of several stress exposures. These data provide preliminary evidence for a relationship between questionnaire scales aiming at assessing personality traits and cortisol stress responses uncovered by repeated stress exposure and data aggregation. While novelty may mask the impact of personality on the cortisol stress response on the first exposure, differences in the ability to cope with the stressful situation may lead to different cortisol stress response patterns on subsequent stress exposures. With data aggregation, an association between the trait component of cortisol stress responses and questionnaire scales might be uncovered. For reliable investigation of correlations between personality variables and cortisol stress responses, repeated stress exposure and data aggregation is suggested.

Enhanced dexamethasone suppression of plasma cortisol in adult women traumatized by childhood sexual abuse

A study was undertaken to determine if female survivors of childhood and/or adolescent sexual abuse (CSA) would exhibit hypothalamic-pituitary-adrenal (HPA) axis abnormalities characteristic of patients with combat-related posttraumatic stress disorder (PTSD)--i.e., enhanced cortisol suppression to low-dose dexamethasone and increased density of lymphocyte glucocorticoid receptors. Nineteen women who reported experiencing severe CSA and 21 nonvictimized women participated in a low-dose (0.5 mg) dexamethasone suppression test and donated blood for measurement of lymphocyte glucocorticoid receptor binding. Women with CSA had significantly enhanced suppression of plasma cortisol in response to 0.5 mg dexamethasone compared to the nonvictimized women. These observations are consistent with findings in male veterans with combat-related PTSD. They suggest that this pattern of HPA axis dysfunction may be a characteristic sequel of psychiatric disorders that occur following a range of traumatic experiences. This HPA axis profile is different than that associated with acute stress or with major depressive disorder.

Psychological and endocrine abnormalities in refugees from East Germany: Part II. Serum levels of cortisol, prolactin, luteinizing hormone, follicle stimulating hormone, and testosterone

We investigated afternoon serum levels of cortisol, prolactin, luteinizing hormone (LH), follicle stimulating hormone (FSH), and testosterone in a group of 84 refugees who had fled from East to West Germany and suffered from psychiatric disorders within 6 weeks of their arrival in West Berlin. The mean hormone levels were compared with those of healthy control subjects. Cortisol levels were lower and LH levels were higher in the patients than in the control subjects, but only at trend levels of significance. No differences were found between the prolactin, FSH, or testosterone concentrations of the two groups. The patients with major depressive disorder (MDD) had a significantly higher mean cortisol level than the mean levels in the subgroups in whom posttraumatic stress disorder, dysthymia, and adjustment disorder were diagnosed. It can be concluded that the hypothalamic-pituitary-adrenal axis may "adapt" during severe long-term psychological stress and that long-term stress may be only one of the neurochemical mechanisms underlying the hypercortisolemia in patients with MDD.