Linking in vivo brain serotonin type 1B receptor density to phenotypic heterogeneity of posttraumatic stress symptomatology

Is factor analysis useful for revising diagnostic criteria for PTSD? A systematic review of five issues ten years after DSM-5

BACKGROUND

Based on factor analysis research, DSM-5 revised the diagnostic criteria for posttraumatic stress disorder (PTSD) by increasing symptom clusters from three to four.

AIMS

To question whether that is an appropriate use of factor analysis.

METHODS

Reviewed the literature on five issues of factor analysis relevant to diagnostic criteria: (1) discovery of factors identical to symptom clusters, (2) consensus about the number of factors in best-fitting models, (3) configural variance between subpopulations to explain inconsistent model results, (4) methods to externally validate factors after discovery, and (5) treatment response of symptom clusters to externally validate factors. Two hundred four articles using DSM-IV or DSM-5 symptoms were included.

RESULTS

Two of four DSM-5 clusters were discovered with exploratory factor analysis. Support for a best-fitting model was inconsistent. Models with the highest number of factors were the best mathematical fit 87% of the time. Subpopulations did not reveal a pattern of configural variance to explain inconsistent findings. External validation of factors relied entirely on questionnaires. A review of 143 randomized controlled trials did not reveal differential treatment response of any symptom cluster.

CONCLUSION

Findings did not support the usefulness of factor analysis because the findings are too disparate to be helpful.

Reduced serotonergic transmission alters sensitivity to cost and reward via 5-HT1A and 5-HT1B receptors in monkeys

Serotonin (5-HT) deficiency is a core biological pathology underlying depression and other psychiatric disorders whose key symptoms include decreased motivation. However, the exact role of 5-HT in motivation remains controversial and elusive. Here, we pharmacologically manipulated the 5-HT system in macaque monkeys and quantified the effects on motivation for goal-directed actions in terms of incentives and costs. Reversible inhibition of 5-HT synthesis increased errors and reaction times on goal-directed tasks, indicating reduced motivation. Analysis found incentive-dependent and cost-dependent components of this reduction. To identify the receptor subtypes that mediate cost and incentive, we systemically administered antagonists specific to 4 major 5-HT receptor subtypes: 5-HT1A, 5-HT1B, 5-HT2A, and 5-HT4. Positron emission tomography (PET) visualized the unique distribution of each subtype in limbic brain regions and determined the systemic dosage for antagonists that would achieve approximately 30% occupancy. Only blockade of 5-HT1A decreased motivation through changes in both expected cost and incentive; sensitivity to future workload and time delay to reward increased (cost) and reward value decreased (incentive). Blocking the 5-HT1B receptor also reduced motivation through decreased incentive, although it did not affect expected cost. These results suggest that 5-HT deficiency disrupts 2 processes, the subjective valuation of costs and rewards, via 5-HT1A and 5-HT1B receptors, thus leading to reduced motivation.

Emphasizing the Crosstalk Between Inflammatory and Neural Signaling in Post-traumatic Stress Disorder (PTSD)

Post-traumatic stress disorder (PTSD) is a chronic incapacitating condition with recurrent experience of trauma-related memories, negative mood, altered cognition, and hypervigilance. Agglomeration of preclinical and clinical evidence in recent years specified that alterations in neural networks favor certain characteristics of PTSD. Besides the disruption of hypothalamus-pituitary-axis (HPA) axis, intensified immune status with elevated pro-inflammatory cytokines and arachidonic metabolites of COX-2 such as PGE2 creates a putative scenario in worsening the neurobehavioral facet of PTSD. This review aims to link the Diagnostic and Statistical Manual of mental disorders (DSM-V) symptomology to major neural mechanisms that are supposed to underpin the transition from acute stress reactions to the development of PTSD. Also, to demonstrate how these intertwined processes can be applied to probable early intervention strategies followed by a description of the evidence supporting the proposed mechanisms. Hence in this review, several neural network mechanisms were postulated concerning the HPA axis, COX-2, PGE2, NLRP3, and sirtuins to unravel possible complex neuroinflammatory mechanisms that are obscured in PTSD condition.

Reexperiencing and anxious arousal symptoms in relation to volumes of thalamus nuclei in posttraumatic stress spectrum adults

INTRODUCTION

Trauma reexperiencing is dominated by recollection of sensory-perceptual elements of the trauma, pointing to involvement of the sensory thalamus. This study examined posttraumatic stress symptoms in relation to volumes of thalamic nuclei that were grouped based on their predominant functions. We hypothesized that reexperiencing, controlling for other symptom dimensions, would correlate with volumes of thalamic nuclei involved in primary and higher-order sensory processing.

METHODS

Seventy-two trauma-exposed adults were interviewed with the Clinician Administered PTSD Scale for DSM-IV and underwent 3T magnetic resonance imaging. Scores were derived for reexperiencing, anxious arousal, dysphoric arousal, emotional numbing, and avoidance symptoms. These were entered as simultaneous predictors in five separate regression analyses, with age, sex, and total thalamus volume as covariates, predicting volumesf of five thalamus nuclear groupings corrected for intracranial volume: Specific sensory, associative-sensory, associative-cognitive, intralaminar, and motor groupings.

RESULTS

Reexperiencing symptoms were significantly positively correlated with volumes of the motor thalamic grouping, which included the ventral anterior, ventral lateral, and ventromedial nuclei. Anxious arousal was significantly negatively correlated with volumes of all five thalamic groupings.

CONCLUSIONS

Reexperiencing symptoms were correlated with volumes of the motor thalamus, while anxious arousal symptoms were related to all thalamic subregion volumes. Thalamic nuclei involved in motor functions, including oculomotor control and motor planning, may be implicated in posttraumatic reexperiencing symptoms.

Elucidating posttraumatic stress symptom dimensions and health correlates among postpartum women

BACKGROUND

Posttraumatic stress disorder (PTSD) is associated with interpersonal dysfunction and adverse maternal health during the perinatal period (extending from conception through one year postpartum). However, PTSD is a heterogeneous disorder, and little is known about which aspects of this disorder may be particularly deleterious to the health of new mothers. Such data may inform more personalized approaches to PTSD prevention and treatment among postpartum women.

METHODS

Using confirmatory factor analysis, we compared three models of PTSD symptom structure-the four-factor dysphoria model, four-factor emotional numbing model, and five-factor dysphoric arousal model-in 1,663 postpartum women from the Community and Child Health Network (CCHN). We examined associations between PTSD symptom dimensions of the best-fitting model with four correlates relevant to maternal health and functioning-parenting stress, partner relationship stress, relationship satisfaction, and contraceptive use.

RESULTS

Though all models fit well, the five-factor dysphoric arousal model provided optimal fit. Symptom dimensions from this model-re-experiencing, avoidance, numbing, dysphoric arousal, and anxious arousal-evidenced differential associations with the maternal health indicators. Numbing symptoms were most strongly associated with indicators of poor interpersonal functioning, whereas dysphoric arousal symptoms were most strongly related to low-efficacy contraceptive use.

LIMITATIONS

Our cross-sectional study assessed DSM-IV PTSD symptoms.

CONCLUSIONS

PTSD symptoms among postpartum women are best-represented by five factors. Numbing symptoms (e.g., restricted affect, detachment) are most strongly associated with interpersonal difficulties, whereas dysphoric arousal symptoms (e.g., agitation, irritability) are linked with low-efficacy contraceptive use. Screening for these symptoms may help promote the health of new mothers.

Contribution of Hippocampal 5-HT3 Receptors in Hippocampal Autophagy and Extinction of Conditioned Fear Responses after a Single Prolonged Stress Exposure in Rats

One of the hypotheses about the pathogenesis of posttraumatic stress disorder (PTSD) is the dysfunction of serotonin (5-HT) neurotransmission. While certain 5-HT receptor subtypes are likely critical for the symptoms of PTSD, few studies have examined the role of 5-HT3 receptor in the development of PTSD, even though 5-HT3 receptor is critical for contextual fear extinction and anxiety-like behavior. Therefore, we hypothesized that stimulation of 5-HT3 receptor in the dorsal hippocampus (DH) could prevent hippocampal autophagy and the development of PTSD-like behavior in animals. To this end, we infused SR57227, selective 5-HT3 agonist, into the DH after a single prolonged stress (SPS) treatment in rats. Three weeks later, we evaluated the effects of this pharmacological treatment on anxiety-related behaviors and extinction of contextual fear memory. We also accessed hippocampal autophagy and the expression of 5-HT3A subunit, Beclin-1, LC3-I, and LC3-II in the DH. We found that SPS treatment did not alter anxiety-related behaviors but prolonged the extinction of contextual fear memory, and such a behavioral phenomenon was correlated with increased hippocampal autophagy, decreased 5-HT3A expression, and increased expression of Beclin-1 and LC3-II/LC3-I ratio in the DH. Furthermore, intraDH infusions of SR57227 dose-dependently promoted the extinction of contextual fear memory, prevented hippocampal autophagy, and decreased expression of Beclin-1 and LC3-II/LC3-I ratio in the DH. These results indicated that 5-HT3 receptor in the hippocampus may play a critical role in the pathogenesis of hippocampal autophagy, and is likely involved in the pathophysiology of PTSD.

Support for the association between RORA gene polymorphisms and the DSM-5 posttraumatic stress disorder symptoms in male earthquake survivors in China

BACKGROUND

This study examined the association between interaction of retinoid-related orphan receptor alpha (RORA) (rs8042149) genotype x trauma exposure and post-traumatic stress disorder (PTSD) symptoms.

METHODS

A total of 1196 Chinese adults who suffered from a deadly 2008 Wenchuan earthquake participated in this study. PTSD symptoms were measured with the PTSD Checklist for DSM-5 (PCL-5). A custom-by-design 2×48-Plex SNPscan™Kit were used to genotype the RORA rs8042149 SNP.

RESULTS

Our results showed that the interaction of rs8042149 genotype x trauma exposure was associated with total PTSD symptoms in males. Moreover, the rs8042149 genotype x trauma exposure interaction was only associated with severity of the negative affect, anhedonia and dysphoric arousal symptoms in males.

LIMITATIONS

A moderate sample exposed to a specific event was assessed with a self-reported PTSD measure.

CONCLUSIONS

This study provides preliminary evidence supporting the functional role of RORA in PTSD, and adds to the knowledge for understanding the genetic underpinnings of PTSD. Moreover, this study carries implications for understanding the comorbidity of PTSD and the sex-specific expression of PTSD's symptoms.

Molecular Neuroimaging in Posttraumatic Stress Disorder

Over the past decade, an increasing number of neuroimaging studies have provided insight into the neurobiological mechanisms of posttraumatic stress disorder (PSTD). In particular, molecular neuroimaging techniques have been employed in examining metabolic and neurochemical processes in PTSD. This article reviews molecular neuroimaging studies in PTSD and focuses on findings using three imaging modalities including positron emission tomography (PET), single photon emission computed tomography (SPECT), and magnetic resonance spectroscopy (MRS). Although there were some inconsistences in the findings, patients with PTSD showed altered cerebral metabolism and perfusion, receptor bindings, and metabolite profiles in the limbic regions, medial prefrontal cortex, and temporal cortex. Studies that have investigated brain correlates of treatment response are also reviewed. Lastly, the limitations of the molecular neuroimaging studies and potential future research directions are discussed.

Intrusive memories to traumatic footage: the neural basis of their encoding and involuntary recall

BACKGROUND

A hallmark symptom after psychological trauma is the presence of intrusive memories. It is unclear why only some moments of trauma become intrusive, and how these memories involuntarily return to mind. Understanding the neural mechanisms involved in the encoding and involuntary recall of intrusive memories may elucidate these questions.

METHOD

Participants (n = 35) underwent functional magnetic resonance imaging (fMRI) while being exposed to traumatic film footage. After film viewing, participants indicated within the scanner, while undergoing fMRI, if they experienced an intrusive memory of the film. Further intrusive memories in daily life were recorded for 7 days. After 7 days, participants completed a recognition memory test. Intrusive memory encoding was captured by comparing activity at the time of viewing 'Intrusive scenes' (scenes recalled involuntarily), 'Control scenes' (scenes never recalled involuntarily) and 'Potential scenes' (scenes recalled involuntarily by others but not that individual). Signal change associated with intrusive memory involuntary recall was modelled using finite impulse response basis functions.

RESULTS

We found a widespread pattern of increased activation for Intrusive v. both Potential and Control scenes at encoding. The left inferior frontal gyrus and middle temporal gyrus showed increased activity in Intrusive scenes compared with Potential scenes, but not in Intrusive scenes compared with Control scenes. This pattern of activation persisted when taking recognition memory performance into account. Intrusive memory involuntary recall was characterized by activity in frontal regions, notably the left inferior frontal gyrus.

CONCLUSIONS

The left inferior frontal gyrus may be implicated in both the encoding and involuntary recall of intrusive memories.

The Relationship between Cortisol Activity during Cognitive Task and Posttraumatic Stress Symptom Clusters

Background

The latest development in the dimensional structure of posttraumatic stress disorder (PTSD) is a novel 6-factor model, which builds on the newly released DSM-5. One notable gap in the literature is that little is known about how distinct symptom clusters of PTSD are related to hypothalamic–pituitary–adrenal (HPA) axis activity when people perform a relatively less stressful cognitive task. The purpose of this study was to investigate the relationship between cortisol activity when individuals perform cognitive tasks in the laboratory and a contemporary phenotypic model of posttraumatic stress symptomatology in earthquake survivors.

Methods

Salivary cortisol while performing cognitive tasks was collected and analyzed in 89 adult earthquake survivors. The PTSD Checklist for the DSM-5 (PCL-5) was used to assess the severity of total PTSD as well as six distinct symptom clusters. Regression analyses were conducted to examine the associations between the six distinct PTSD symptom clusters and cortisol profiles.

Results

The results showed that the score of the negative affect symptom cluster, but not anhedonia or other clusters, was positively associated with cortisol levels before and during the cognitive tasks.

Conclusion

The results showed that higher cortisol levels before and during cognitive tasks might be specifically linked to a distinct symptom cluster of PTSD—negative affect symptomatology. This suggests that a distinction should be made between negative affect and anhedonia symptom clusters, as the 6-factor model proposed.

Dimensional structure and correlates of posttraumatic stress symptoms following suspected acute coronary syndrome

BACKGROUND

Posttraumatic stress disorder (PTSD) is a heterogeneous construct, and some have suggested that PTSD triggered by acute coronary syndrome (ACS) may differ from PTSD due to prototypical traumas.

METHODS

We conducted the first examination of the latent structure of PTSD symptoms after suspected ACS in 399 adults in the REactions to Acute Care and Hospitalization (REACH) study, an observational cohort study of patients recruited from the emergency department during evaluation for ACS. Using confirmatory factor analysis, we compared the 4-factor dysphoria, 4-factor numbing, and 5-factor dysphoric arousal models of PTSD.

RESULTS

Although all models fit well, the dysphoria model was selected as the best-fitting model. Further, there was measurement invariance of the dysphoria model by sex. PTSD dimensions evidenced differential associations with indicators of threat perception during ACS evaluation and adherence to cardioprotective medication.

LIMITATIONS

One limitation of this investigation is the use of self-report measures. In addition, only one-third of the sample was diagnosed with ACS at discharge; the remaining participants received diagnoses such as chest pain without a cardiac diagnosis, another symptom/disease process (e.g., hypertensive chronic kidney disease), or another cardiac disease.

CONCLUSIONS

Findings suggest that suspected ACS-related PTSD symptoms are best-represented by a 4-factor structure distinguishing between specific (e.g., re-experiencing) and non-specific (dysphoria) symptoms of PTSD that has received support in the broader PTSD literature.

Hair cortisone level is associated with PTSD׳s dysphoric arousal symptoms in highly traumatized Chinese females

BACKGROUND

Cortisone has been proposed as a useful additional biomarker for stress research. However, only very limited studies has investigated alterations of cortisone levels in stress-related mental disorder such as PTSD. The present study investigated the associations between PTSD symptomatology and hair cortisone levels which can reflect cumulative cortisone secretion over prolonged periods of time and is more robust to the influence of situational confounding.

METHODS

Participants included 201 females who experienced 2008 Wenchuan earthquake and lost their children during the disaster. PTSD symptoms were assessed with the PTSD Checklist (PCL), and depression symptoms with the Center for epidemiological studies depression scale (CES-D). Hair cortisone levels were quantified by liquid chromatography tandem mass spectrometer.

RESULTS

The results indicated that although hair cortisone secretion could not distinguish traumatized individuals with and without PTSD, it was uniquely linked to dysphoric arousal symptoms, a key aspect of the complex PTSD phenotype

LIMITATIONS

A sample of females exposed to specific traumatic events was used, and PTSD was assessed using a self-reported measure.

CONCLUSIONS

The findings provide preliminary evidence supporting the critical role of long-term cortisone changes in the development and maintenance of PTSD symptoms, and add to extant knowledge on the neuroendocrinological underpinnings of posttraumatic psychopathology.

Investigational drugs under development for the treatment of PTSD

INTRODUCTION

Posttraumatic stress disorder (PTSD) is a prevalent, chronic and disabling anxiety disorder that may develop following exposure to a traumatic event. There is currently no effective pharmacotherapy for PTSD and therefore the discovery of novel, evidence-based treatments is particularly important. This review of potential novel treatments could act as a catalyst for further drug investigation.

AREAS COVERED

In this review, the authors discuss the heterogeneity of PTSD and why this provides a challenge for discovering effective treatments for this disorder. By searching for the neurobiological systems that are disrupted in individuals with PTSD and their correlation with different symptoms, the authors propose potential pharmacological treatments that could target these symptoms. They discuss drugs such as nabilone, d-cycloserine, nor-BNI, 7,8-dihydroxyflavone and oxytocin (OT) to target systems such as cannabinoids, glutamate, opioids, brain-derived neurotrophic factor and the OT receptor, respectively. While not conclusive, the authors believe that these brain systems include promising targets for drug discovery. Finally, the authors review animal studies, proof-of-concept studies and case studies that support our proposed treatments.

EXPERT OPINION

A mechanism-based approach utilizing techniques such as in vivo neuroimaging will allow for the determination of treatments. Due to the heterogeneity of the PTSD phenotype, focusing on symptomology rather than a categorical diagnosis will allow for more personalized treatment. Furthermore, there appears to be a promise in drugs as cognitive enhancers, the use of drug cocktails and novel compounds that target specific pathways linked to the etiology of PTSD.

The relationship between response inhibition and posttraumatic stress symptom clusters in adolescent earthquake survivors: an event-related potential study

Posttraumatic stress disorder (PTSD) patients experience impaired response inhibition. Little is known about the relationship between response inhibition abnormalities and distinct PTSD symptom clusters. This study investigated the relationship between response inhibition processing and a five-factor model of posttraumatic stress symptomatology in adolescents. The event-related potentials of 54 unmedicated adolescent earthquake survivors (age 15–18 years) were recorded as they completed a Go/NoGo task. The PTSD Checklist-Specific Stressor Version (PCL-S) was used to assess PTSD symptoms. Regression analyses were conducted to examine the associations between the five symptom-cluster model and response inhibition processing. The results revealed that the avoidance symptom cluster score, but not the numbing or other clusters' scores, was positively associated with NoGo-P3 latency. These results suggest that a specific PTSD symptom cluster—avoidance—has a distinct association with the slowed speed of the late step of response inhibition processing, i.e., decision or success of response inhibition in adolescent earthquake survivors.

Translational evidence for a role of endocannabinoids in the etiology and treatment of posttraumatic stress disorder

INTRODUCTION

Posttraumatic stress disorder (PTSD) is a prevalent, chronic, and disabling anxiety disorder that may develop following exposure to a traumatic event. Despite the public health significance of PTSD, relatively little is known about the etiology or pathophysiology of this disorder, and pharmacotherapy development to date has been largely opportunistic instead of mechanism-based. Recently, an accumulating body of evidence has implicated the endocannabinoid system in the etiology of PTSD, and targets within this system are believed to be suitable for treatment development.

METHODS

Herein, we describe evidence from translational studies arguing for the relevance of the endocannabinoid system in the etiology of PTSD. We also show mechanisms relevant for treatment development.

RESULTS

There is convincing evidence from multiple studies for reduced endocannabinoid availability in PTSD. Brain imaging studies show molecular adaptations with elevated cannabinoid type 1 (CB1) receptor availability in PTSD which is linked to abnormal threat processing and anxious arousal symptoms.

CONCLUSION

Of particular relevance is evidence showing reduced levels of the endocannabinoid anandamide and compensatory increase of CB1 receptor availability in PTSD, and an association between increased CB1 receptor availability in the amygdala and abnormal threat processing, as well as increased severity of hyperarousal, but not dysphoric symptomatology, in trauma survivors. Given that hyperarousal symptoms are the key drivers of more disabling aspects of PTSD such as emotional numbing or suicidality, novel, mechanism-based pharmacotherapies that target this particular symptom cluster in patients with PTSD may have utility in mitigating the chronicity and morbidity of the disorder.

Dimensional structure and course of post-traumatic stress symptomatology in World Trade Center responders

BACKGROUND

Post-traumatic stress disorder (PTSD) in response to the World Trade Center (WTC) disaster of 11 September 2001 (9/11) is one of the most prevalent and persistent health conditions among both professional (e.g. police) and non-traditional (e.g. construction worker) WTC responders, even several years after 9/11. However, little is known about the dimensionality and natural course of WTC-related PTSD symptomatology in these populations.

METHOD

Data were analysed from 10 835 WTC responders, including 4035 police and 6800 non-traditional responders who were evaluated as part of the WTC Health Program, a clinic network in the New York area established by the National Institute for Occupational Safety and Health. Confirmatory factor analyses (CFAs) were used to evaluate structural models of PTSD symptom dimensionality; and autoregressive cross-lagged (ARCL) panel regressions were used to examine the prospective interrelationships among PTSD symptom clusters at 3, 6 and 8 years after 9/11.

RESULTS

CFAs suggested that five stable symptom clusters best represent PTSD symptom dimensionality in both police and non-traditional WTC responders. This five-factor model was also invariant over time with respect to factor loadings and structural parameters, thereby demonstrating its longitudinal stability. ARCL panel regression analyses revealed that hyperarousal symptoms had a prominent role in predicting other symptom clusters of PTSD, with anxious arousal symptoms primarily driving re-experiencing symptoms, and dysphoric arousal symptoms primarily driving emotional numbing symptoms over time.

CONCLUSIONS

Results of this study suggest that disaster-related PTSD symptomatology in WTC responders is best represented by five symptom dimensions. Anxious arousal symptoms, which are characterized by hypervigilance and exaggerated startle, may primarily drive re-experiencing symptoms, while dysphoric arousal symptoms, which are characterized by sleep disturbance, irritability/anger and concentration difficulties, may primarily drive emotional numbing symptoms over time. These results underscore the importance of assessment, monitoring and early intervention of hyperarousal symptoms in WTC and other disaster responders.

The underlying dimensions of DSM-5 posttraumatic stress disorder symptoms in an epidemiological sample of Chinese earthquake survivors

The current study investigated the underlying dimensions of DSM-5 PTSD symptoms in an epidemiological sample of Chinese earthquake survivors. The sample consisted of 810 females and 386 males, with a mean age of 47.9 years (SD=10.0, range: 16-73). PTSD symptoms were assessed using the PTSD Checklist for DSM-5, and alternative models were evaluated with confirmatory factor analysis. Results indicated that a six-factor model comprised of intrusion, avoidance, negative affect, anhedonia, dysphoric arousal, and anxious arousal factors emerged as the best fitting model. The current findings add to limited literature on the latent structure of PTSD symptoms described in the recently released DSM-5, and carry implications for further trauma-related research and clinical practice.

Linking plasma cortisol levels to phenotypic heterogeneity of posttraumatic stress symptomatology

INTRODUCTION

Recent confirmatory factor analytic studies of the dimensional structure of posttraumatic stress disorder (PTSD) suggest that this disorder may be best characterized by five symptom dimensions-re-experiencing, avoidance, numbing, dysphoric arousal, and anxious arousal. Hypothalamic-pituitary-adrenal (HPA) axis dysregulation in PTSD and has been attributed to enhanced glucocorticoid responsiveness. However, little is known about how altered HPA-axis function is related to this contemporary phenotypic model of PTSD.

METHODS

We compared morning plasma cortisol levels of drug-free civilian adults with PTSD (N = 29) to trauma-exposed (TC; N = 12) and non-trauma-exposed healthy controls (HC; N = 23). We then examined the relation between cortisol levels and a contemporary 5-factor 'dysphoric arousal' model of PTSD symptoms among individuals with PTSD.

RESULTS

After adjustment for white race/ethnicity, education, lifetime alcohol use disorder, and current smoking status, the PTSD (Cohen's d = 1.1) and TC (Cohen's d = 1.3) groups had significantly lower cortisol levels than the HC group; cortisol levels did not differ between the TC and PTSD groups. Except for age (r = -.46), none of the other demographic, trauma-related, or clinical variables, including lifetime mood/anxiety disorder and severity of current depressive and anxiety symptoms, were associated with cortisol levels. In a stepwise linear regression analysis, age (β = -.44) and severity of emotional numbing symptoms (β = -.35) were independently associated with cortisol levels in the PTSD group; none of the other PTSD symptom clusters or depression symptoms were significant. Post hoc analyses revealed that severity of the emotional numbing symptom of restricted range of affect (i.e., unable to have loving feelings) was independently related to cortisol levels (β = -.35).

CONCLUSION

These results suggest that trauma-exposed civilian adults with and without PTSD have significantly lower cortisol levels compared to healthy, non-trauma-exposed adults. They further suggest that low cortisol levels among adults with PTSD may be specifically linked to emotional numbing symptomatology that is unique to the PTSD phenotype and unrelated to depressive symptoms.

Association of posttraumatic stress disorder with reduced in vivo norepinephrine transporter availability in the locus coeruleus

IMPORTANCE

Animal data suggest that chronic stress is associated with a reduction in norepinephrine transporter (NET) availability in the locus coeruleus. However, it is unclear whether such models are relevant to posttraumatic stress disorder (PTSD), which has been linked to noradrenergic dysfunction in humans.

OBJECTIVES

To use positron emission tomography and the radioligand [11C]methylreboxetine to examine in vivo NET availability in the locus coeruleus in the following 3 groups of individuals: healthy adults (HC group), adults exposed to trauma who did not develop PTSD (TC group), and adults exposed to trauma who developed PTSD (PTSD group) and to evaluate the relationship between NET availability in the locus coeruleus and a contemporary phenotypic model of PTSD symptoms.

DESIGN, SETTING, AND PARTICIPANTS

Cross-sectional positron emission tomography study under resting conditions at academic and Veterans Affairs medical centers among 56 individuals in the following 3 study groups: HC (n = 18), TC (n = 16), and PTSD (n = 22).

MAIN OUTCOMES AND MEASURES

The [11C]methylreboxetine-binding potential of NET availability in the locus coeruleus and the severity of PTSD symptoms assessed using the Clinician-Administered PTSD Scale.

RESULTS

The PTSD group had significantly lower NET availability than the HC group (41% lower, Cohen d = 1.07). NET availability did not differ significantly between the TC and HC groups (31% difference, Cohen d = 0.79) or between the TC and PTSD groups (15% difference, Cohen d = 0.28). In the PTSD group, NET availability in the locus coeruleus was independently positively associated with the severity of anxious arousal (ie, hypervigilance) symptoms (r = 0.52) but not with any of the other PTSD symptom clusters.

CONCLUSIONS AND RELEVANCE

These results suggest that PTSD is associated with significantly reduced NET availability in the locus coeruleus and that greater NET availability in this brain region is associated with increased severity of anxious arousal symptoms in individuals with PTSD.

Stathmin genotype is associated with reexperiencing symptoms of posttraumatic stress disorder in Chinese earthquake survivors

Stathmin (STMN1) has been demonstrated as a regulator of fear processing across species, which implicates that it may be important in the etiopathogenesis of fear-related psychiatric disorders such as posttraumatic stress disorder (PTSD). This study examined the association between STMN1 rs182455 genotype, a single nucleotide polymorphism (SNP) located within or close to the putative transcriptional control region of STMN1 gene, and PTSD symptoms. A total of 326 Chinese adults who suffered from a deadly 2008 Wenchuan earthquake and unexpectedly lost their children during the disaster participated in this study. PTSD symptoms were measured with the PTSD Checklist (PCL). The Sequenom iPlex chemistries and the MassARRAY system were used to genotype the STMN1 rs182455 SNP. Our results indicated that the STMN1rs182455 genotype was not associated with severity of total PTSD symptoms in either females or males; however, it could significantly predict severity of PTSD's reexperiencing symptoms in females. The findings provide preliminary evidence supporting the important role of STMN1 in the development of PTSD, and expand extant knowledge on the genetic underpinnings of PTSD and the sex-specific expression of PTSD's symptoms.

Recent progress in understanding the pathophysiology of post-traumatic stress disorder: implications for targeted pharmacological treatment

Post-traumatic stress disorder (PTSD) is a common and chronic anxiety disorder that can result after exposure to a traumatic event. Though our understanding of the aetiology of PTSD is incomplete, several neurobiological systems have been implicated in the pathophysiology and vulnerability towards developing PTSD after trauma exposure. We aimed to provide a concise review of benchmark findings in important neurobiological systems related to the aetiology and maintenance of PTSD symptomology. Specifically, we discuss functional aetiologies in the noradrenergic, serotonergic, endogenous cannabinoid and opioid systems as well as the hypothalamic-pituitary adrenal (HPA) axis. This article provides a succinct framework to appreciate the current understanding of neurobiological mechanisms related to the pathophysiology of PTSD and how these findings may impact the development of future, targeted pharmacological treatments for this debilitating disorder.