The Shared Neuroanatomy and Neurobiology of Comorbid Chronic Pain and PTSD: Therapeutic Implications

Psychiatric Comorbidity in Neurological Disorders: Towards a Multidisciplinary Approach to Illness Management in the United Arab Emirates

Aim: To determine the prevalence of mood and anxiety disorders in undiagnosed patients attending neurological services, and detect rates of referral to and attendance of psychiatric services. Methods: Depressive symptoms and anxiety were assessed in 395 adult patients with primary diagnoses of neurological disorders. The Patient Health Questionnaire nine-item depression scale (PHQ-9), and Generalized Anxiety Disorder seven-item scale (GAD-7) were administered. Demographic details of the patients were recorded. Referral to and attendance of psychiatric services were recorded for patients scoring within the clinical range of depression and anxiety disorders (scores > 10). Results: There was a 39% prevalence rate of depressive symptoms, 34% rate of anxiety, and 35.4% concurrent rate of both disorders in this cohort. The referral rate to psychiatric services was 33.6%, and attendance rate was 47.8%. There was significant association between severity of psychiatric symptoms and referral to psychiatric services, as well as significant association between comorbid psychiatric symptoms and attendance to psychiatric services. Conclusion: Our results indicate similar prevalence rates of comorbid psychiatric symptoms to studies carried out in the Middle East and North Africa (MENA) region and relatively high attendance and referral rates to psychiatric services. Implications: The results shed light on the clinical profile of patients in this region and support the need for integrated collaborative medical services. Moreover, findings have important implications for health care policies pertaining to resource distribution and funding.

Systematic review of in-vivo neuro magnetic resonance spectroscopy for the assessment of posttraumatic stress disorder

Posttraumatic stress disorder (PTSD) is a trauma and stressor-related disorder that results in complex somatic, cognitive, affective and behavioural effects, after exposure to traumatic event(s). Conventional imaging (T1 and T2 weighted magnetic resonance imaging) has little to offer in the way of diagnosis of mental health conditions such as PTSD and there is currently no objective diagnostic test available. Magnetic resonance spectroscopy (MRS) allows for non-invasive measurement of metabolites and neurochemicals in the brain using a conventional MRI scanner and offers the potential to predict, diagnose and monitor PTSD. This systematic review summarises the results of 24 MRS studies, performed between 1998 and 2017, to measure neurochemical differences, occurring as a consequence of PTSD. The most consistent finding in subjects with PTSD is lower N-acetylaspartate levels in the hippocampus and anterior cingulate cortex, with and without atrophic change. More recent studies, using more advanced techniques and modern hardware, have shown evidence of glutamatergic dysfunction and differences in gamma-aminobutyric acid levels in the brain of patients with PTSD. Conflicting results have been reported in choline-containing metabolites and there is emerging evidence of glutathione being affected. Myo-inositol and creatine are unchanged in the majority of studies.

Factors mediating the impacts of child abuse and intimate partner violence on chronic pain: a cross-sectional study

BACKGROUND

Most research on the health impacts of intimate partner violence (IPV) and child abuse has been conducted in Western countries and may not be generalizable to women living in different contexts, such as Saudi Arabia. Chronic pain, a disabling health issue associated with experiences of both child abuse and IPV among women, negatively impacts women's well-being, quality of life, and level of functioning. Yet, the psychosocial mechanisms that explain how abuse relates to chronic pain are poorly understood. We developed and tested a theoretical model that explains how both IPV and child abuse are related to chronic pain.

METHODS

We recruited a convenience sample of 299 Saudi women, who had experienced IPV in the past 12 months, from nine primary health care centers in Saudi Arabia between June and August 2015. Women completed a structured interview comprised of self-report measures of IPV, child abuse, PTSD, depressive symptoms, chronic pain, and social support. Using Structural equation modeling (SEM), we analyzed the proposed model twice with different mental health indicators as mediators: PTSD symptoms (Model 1) and depressive symptoms (Model 2).

RESULTS

Both models were found to fit the data, accounting for 31.6% (Model 1) and 32.4% (Model 2) of the variance in chronic pain severity. In both models, mental health problems (PTSD and depressive symptoms) fully mediated the relationship between severity of IPV and child abuse and chronic pain severity. Perceived family support partially mediated the relationship between abuse severity and depressive symptoms.

CONCLUSIONS

These results underscore the significance of considering lifetime abuse, women's mental health (depressive and PTSD symptoms) and their social resources in chronic pain management and treatment.

Neurotransmitter, Peptide, and Steroid Hormone Abnormalities in PTSD: Biological Endophenotypes Relevant to Treatment

PURPOSE OF REVIEW

This review summarizes neurotransmitter, peptide, and other neurohormone abnormalities associated with posttraumatic stress disorder (PTSD) and relevant to development of precision medicine therapeutics for PTSD.

RECENT FINDINGS

As the number of molecular abnormalities associated with PTSD across a variety of subpopulations continues to grow, it becomes clear that no single abnormality characterizes all individuals with PTSD. Instead, individually variable points of molecular dysfunction occur within several different stress-responsive systems that interact to produce the clinical PTSD phenotype. Future work should focus on critical interactions among the systems that influence PTSD risk, severity, chronicity, comorbidity, and response to treatment. Effort also should be directed toward development of clinical procedures by which points of molecular dysfunction within these systems can be identified in individual patients. Some molecular abnormalities are more common than others and may serve as subpopulation biological endophenotypes for targeting of currently available and novel treatments.

Traumatic Stress and Pediatric Pain: Towards a Neurobiological Stress-Health Perspective

This theoretical review aims to present the limited findings on traumatic stress and pain in children and adolescents, highlight recent discoveries regarding neurobiological processes, and suggest an alternative stress-health perspective in the future study and conceptualization of pediatric pain and traumatic stress based on results. Current literature highlights a positive correlation between pain and trauma symptoms in youth and suggests a complex relationship that may have mutually maintaining dynamics and intertwined physiological processes. Developmentally sensitive, longitudinal, process-oriented designs assessing neurobiological alterations and stress responses should be utilized in the examination of the trauma-pain relationship. Such investigations may provide a more unified explanation of the relationship between chronic pain and traumatic stress.

Chronic Pain Types Differ in Their Reported Prevalence of Post -Traumatic Stress Disorder (PTSD) and There Is Consistent Evidence That Chronic Pain Is Associated with PTSD: An Evidence-Based Structured Systematic Review

Objectives

The hypotheses of this systematic review were the following: 1) Prevalence of post-traumatic stress disorder (PTSD) will differ between various types of chronic pain (CP), and 2) there will be consistent evidence that CP is associated with PTSD.

Methods

Of 477 studies, 40 fulfilled the inclusion/exclusion criteria of this review and were grouped according to the type of CP. The reported prevalence of PTSD for each grouping was determined by aggregating all the patients in all the studies in that group. Additionally all patients in all groupings were combined. Percentage of studies that had found an association between CP and PTSD was determined. The consistency of the evidence represented by the percentage of studies finding an association was rated according to the Agency for Health Care Policy and Research guidelines.

Results

Grouping PTSD prevalence differed ranging from a low of 0.69% for chronic low back pain to a high of 50.1% in veterans. Prevalence in the general population with CP was 9.8%. Of 19 studies, 16 had found an association between CP and PTSD (84.2%) generating an A consistency rating (consistent multiple studies). Three of the groupings had an A or B (generally consistent) rating. The veterans grouping received a C (finding inconsistent) rating.

Conclusion

The results of this systematic review confirmed the hypotheses of this review.

The Association between Daily Posttraumatic Stress Symptoms and Pain over the First 14-days after Injury: An Experience Sampling Study

OBJECTIVES

Psychosocial factors and responses to injury modify the transition from acute to chronic pain. Specifically, posttraumatic stress disorder symptoms (PTSS; reexperiencing, avoidance, and hyperarousal symptoms) exacerbate and co-occur with chronic pain. Yet no study has prospectively considered the associations among these psychological processes and pain reports using experience sampling methods (ESM) during the acute aftermath of injury. This study applied ESM via daily text messaging to monitor and detect relationships among psychosocial factors and post-injury pain across the first 14-days after emergency department (ED) discharge.

METHODS

We recruited 75 adults (59% male; M age = 33) who experienced a potentially traumatic injury (i.e., involving life threat or serious injury) in the past 24-hours from the EDs of two Level 1 trauma centers. Participants received 5 questions per day via text messaging from Day-1 to Day-14 post-ED discharge; three questions measured PTSS, one question measured perceived social support, and one question measured physical pain.

RESULTS

Sixty-seven participants provided sufficient data for inclusion in the final analyses, and the average response rate per subject was 86%. Pain severity score decreased from a mean of 7.2 to 4.4 over 14 days and 50% of the variance in daily pain scores was within-person. In multilevel structural equation models, pain scores decreased over time, and daily fluctuations of hyperarousal (b = 0.22, 95% CI [0.08, 0.36]) were uniquely associated with daily fluctuations in reported pain level within each person.

CONCLUSIONS

Daily hyperarousal symptoms predict same-day pain severity over the acute post-injury recovery period. We also demonstrated feasibility to screen and identify patients at risk for pain chronicity in the acute aftermath of injury. Early interventions aimed at addressing hyperarousal (e.g. anxiolytics) could potentially aid in reducing experience of pain. This article is protected by copyright. All rights reserved.

Pain anxiety differentially mediates the association of pain intensity with function depending on level of intolerance of uncertainty

Uncertainty about symptom duration, cause, prognosis and treatment is common in patients who seek medical care, yet individual ability to manage this uncertainty varies. Intolerance of uncertainty is considered an important factor in the etiology and persistence of negative emotions- in particular, depression and anxiety. We explored the contribution of intolerance of uncertainty to anxiety due to pain and physical function in patients seeking care at an orthopedic medical practice. Participants (N = 105, mean age of 51 ± 17, 63% male) were administered PROMIS Physical Function v1.2 Upper Extremity CAT, Numerical Rating Scale (NRS), Pain Anxiety Symptoms Scale-short form (PASS-20), and the Intolerance of Uncertainty Scale-short version (IUS-12). Results showed that the mediating role of pain anxiety is contingent upon the level of intolerance of uncertainty. Specifically, a minimum level of intolerance of uncertainty is required for the development of pain anxiety and its effect on function, and as intolerance of uncertainty rises from low to medium to high levels, the effect of pain on function goes from being independent of the anxiety to being more and more carried by and through anxiety about pain. These findings support the contention that intolerance of uncertainty plays a crucial role in the relationship between pain, pain anxiety, and physical function. Intolerance of uncertainty appears to be a trans-diagnostic target for coping skills training.

Endogenous neurosteroids influence synaptic GABAA receptors during postnatal development

GABA plays a key role in both embryonic and neonatal brain development. For example, during early neonatal nervous system maturation, synaptic transmission, mediated by GABA_A receptors (GABA_A Rs), undergoes a temporally specific form of synaptic plasticity to accommodate the changing requirements of maturing neural networks. Specifically, the duration of miniature inhibitory postsynaptic currents (mIPSCs), resulting from vesicular GABA activating synaptic GABA_A Rs, is reduced, permitting neurones to appropriately influence the window for postsynaptic excitation. Conventionally, programmed expression changes to the subtype of synaptic GABA_A R are primarily implicated in this plasticity. However, it is now evident that, in developing thalamic and cortical principal- and inter-neurones, an endogenous neurosteroid tone (eg, allopregnanolone) enhances synaptic GABA_A R function. Furthermore, a cessation of steroidogenesis, as a result of a lack of substrate, or a co-factor, appears to be primarily responsible for early neonatal changes to GABAergic synaptic transmission, followed by further refinement, which results from subsequent alterations of the GABA_A R subtype. The timing of this cessation of neurosteroid influence is neurone-specific, occurring by postnatal day (P)10 in the thalamus but approximately 1 week later in the cortex. Neurosteroid levels are not static and change dynamically in a variety of physiological and pathophysiological scenarios. Given that GABA plays an important role in brain development, abnormal perturbations of neonatal GABA_A R-active neurosteroids may have not only a considerable immediate, but also a longer-term impact upon neural network activity. Here, we review recent evidence indicating that changes in neurosteroidogenesis substantially influence neonatal GABAergic synaptic transmission. We discuss the physiological relevance of these findings and how the interference of neurosteroid-GABA_A R interaction early in life may contribute to psychiatric conditions later in life.

Prospective Examination of Early Associations of Iraq War Zone Deployment, Combat Severity, and Posttraumatic Stress Disorder with New Incident Medical Diagnoses

War zone deployment and posttraumatic stress disorder (PTSD) have been associated with morbidity and mortality decades later. Less is known about the associations between these variables and the early emergence of medical disorders in war zone veterans. This prospective study of 862 U.S. Army soldiers (n = 569 deployed; n = 293 nondeployed) examined: (a) associations between Iraq War deployment status (deployed vs. nondeployed) and new medical diagnoses that emerged within six months after return from Iraq among all participants; and (b) associations between combat severity and PTSD symptoms, and new postdeployment medical diagnoses that emerged within 12 months after return from Iraq within deployed participants. New medical diagnoses were abstracted from diagnostic codes associated with clinical outpatient visits recorded within the Department of Defense Standard Ambulatory Data Record database. Combat severity was measured with the Combat Experiences module of the Deployment Risk and Resilience Inventory, and postdeployment posttraumatic stress disorder symptom severity was measured using the PTSD Checklist-Civilian. Neither deployment nor combat severity was associated with new medical diagnoses. However, among deployed soldiers, more severe PTSD symptoms were associated with increased risk for a new medical disorder diagnosis; every 10-point increase in PTSD symptoms increased odds of a new diagnosis by nearly 20% (odds ratio = 1.20). Results suggest that PTSD symptoms are associated with early morbidity in Iraq War veterans.

Prevalence of Posttraumatic Stress Disorder in Persons with Chronic Pain: A Meta-analysis

OBJECTIVE

To summarize evidence for the prevalence of posttraumatic stress disorder (PTSD) among persons with chronic pain (CP).

METHODS

We searched databases for studies published between January 1995 and December 2016, reporting the prevalence of PTSD in persons with CP. Two reviewers independently extracted data and assessed the risk of bias. We calculated the pooled prevalence using a random-effects model and performed subgroup analyses according to pain location, the population and assessment method.

RESULTS

Twenty-one studies were included and the PTSD prevalence varied from 0-57%, with a pooled mean prevalence of 9.7%, 95% CI (5.2-17.1). In subgroup analysis, the PTSD prevalence was 20.5%, 95% CI (9.5-39.0) among persons with chronic widespread pain, 11.2%, 95% CI (5.7-22.8) among persons with headache, and 0.3%, 95% CI (0.0-2.4) among persons with back pain. The prevalence in clinical populations was 11.7%, 95% CI (6.0-21.5) and in non-clinical populations 5.1%, 95% CI (0.01-17.2). In studies of self-reported PTSD symptoms, PTSD prevalence was 20.4%, 95% CI (10.6-35.5), and in studies where structured clinical interviews had been used to assess PTSD its prevalence was 4.5%, 95% (CI 2.1-9.3). The risk of bias was medium for most studies and the heterogeneity was high (I2 = 98.6).

CONCLUSION

PTSD is overall more prevalent in clinical cohorts of persons with CP and particularly in those with widespread pain, but may not always be more prevalent in non-clinical samples of persons with CP, compared to the general population. There is a large heterogeneity in prevalence across studies. Future research should identify sources of heterogeneity and the mechanisms underlying the comorbidity of the two conditions.

Neurosteroid biosynthesis down-regulation and changes in GABAA receptor subunit composition: a biomarker axis in stress-induced cognitive and emotional impairment

By rapidly modulating neuronal excitability, neurosteroids regulate physiological processes, such as responses to stress and development. Excessive stress affects their biosynthesis and causes an imbalance in cognition and emotions. The progesterone derivative, allopregnanolone (Allo) enhances extrasynaptic and postsynaptic inhibition by directly binding at GABA_A receptors, and thus, positively and allosterically modulates the function of GABA. Allo levels are decreased in stress-induced psychiatric disorders, including depression and post-traumatic stress disorder (PTSD), and elevating Allo levels may be a valid therapeutic approach to counteract behavioural dysfunction. While benzodiazepines are inefficient, selective serotonin reuptake inhibitors (SSRIs) represent the first choice treatment for depression and PTSD. Their mechanisms to improve behaviour in preclinical studies include neurosteroidogenic effects at low non-serotonergic doses. Unfortunately, half of PTSD and depressed patients are resistant to current prescribed 'high' dosage of these drugs that engage serotonergic mechanisms. Unveiling novel biomarkers to develop more efficient treatment strategies is in high demand. Stress-induced down-regulation of neurosteroid biosynthesis and changes in GABA_A receptor subunit expression offer a putative biomarker axis to develop new PTSD treatments. The advantage of stimulating Allo biosynthesis relies on the variety of neurosteroidogenic receptors to be targeted, including TSPO and endocannabinoid receptors. Furthermore, stress favours a GABA_A receptor subunit composition with higher sensitivity for Allo. The use of synthetic analogues of Allo is a valuable alternative. Pregnenolone or drugs that stimulate its levels increase Allo but also sulphated steroids, including pregnanolone sulphate which, by inhibiting NMDA tonic neurotransmission, provides neuroprotection and cognitive benefits. In this review, we describe current knowledge on the effects of stress on neurosteroid biosynthesis and GABA_A receptor neurotransmission and summarize available pharmacological strategies that by enhancing neurosteroidogenesis are relevant for the treatment of SSRI-resistant patients. Linked Articles This article is part of a themed section on Pharmacology of Cognition: a Panacea for Neuropsychiatric Disease? To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.19/issuetoc.

Parabrachial Pituitary Adenylate Cyclase-Activating Polypeptide Activation of Amygdala Endosomal Extracellular Signal-Regulated Kinase Signaling Regulates the Emotional Component of Pain

BACKGROUND

Chronic pain and stress-related psychopathologies, such as depression and anxiety-associated abnormalities, are mutually reinforcing; however, the neuronal circuits and mechanisms that underlie this reinforcement are still not well understood. Pituitary adenylate cyclase-activating polypeptide (PACAP; Adcyap1) and its cognate PAC1 receptor (Adcyap1r1) are expressed in peripheral nociceptive pathways, participate in anxiety-related responses and have been have been linked to posttraumatic stress disorder and other mental health afflictions.

METHODS

Using immunocytochemistry, pharmacological treatments and behavioral testing techniques, we have used a rodent partial sciatic nerve chronic constriction injury model (n = 5-8 per group per experiment) to evaluate PACAP plasticity and signaling in nociceptive and stress-related behaviors.

RESULTS

We show that chronic neuropathic pain increases PACAP expression at multiple tiers along the spinoparabrachioamygdaloid tract. Furthermore, chronic constriction injury bilaterally augments nociceptive amygdala (in the central nucleus of the amygdala [CeA]) PACAP immunoreactivity, extracellular signal-regulated kinase phosphorylation, and c-Fos activation, in parallel with heightened anxiety-like behavior and nociceptive hypersensitivity. Acute CeA infusions with the PACAP receptor antagonist PACAP(6-38) blocked chronic constriction injury-induced behavioral responses. Additionally, pretreatments with inhibitors of mitogen-activated protein kinase enzymes or endocytosis to block endosomal PACAP receptor extracellular signal-regulated kinase signaling attenuated PACAP-induced CeA neuronal activation and nociceptive responses.

CONCLUSIONS

Our data suggest that chronic pain-induced PACAP neuroplasticity and signaling in spinoparabrachioamygdaloid projections have an impact on CeA stress- and nociception-associated maladaptive responses, which can be ameliorated upon receptor antagonism even during injury progression. Thus, the PACAP pathway provides for an important mechanism underlying the intersection of stress and chronic pain pathways via the amygdala.

P2X3 receptor-mediated visceral hyperalgesia and neuronal sensitization following exposure to PTSD-like stress in the dorsal root ganglia of rats

BACKGROUND

Patients with posttraumatic stress disorder (PTSD) often share co-morbidity with chronic pain conditions. Recent studies suggest a role of P2X3 receptors and ATP signaling in pain conditions. However, the underlying mechanisms of visceral hyperalgesia following exposure to PTSD-like stress conditions remain unclarified.

METHODS

The behavior and hormones relevant for PTSD were studied. Visceromotor responses (VMR) and the abdominal withdrawal reflexes (AWR) to colorectal distention (CRD) were recorded to determine P2X3-receptor-mediated alteration of hyperalgesia following single-prolonged stress (SPS) exposure. Immunofluorescence, Western blotting, and patch-clamp were used.

KEY RESULTS

The escape latency, adrenocorticotropic hormone and cortisol were increased on days 7-14. Visceromotor responses and AWR was reduced at day 1 in SPS rats but increased to higher levels than in controls after exposure to day 7. Intrathecal administration of the P2X3-receptor antagonist TNP-ATP abolished the CRD response. Based on immunofluorescence and Western blotting analysis, SPS-treated rats exhibited reduced P2X3 expression in dorsal root ganglia (DRG) after day 1 compared with controls. P2X3 expression in DRG was enhanced on day 7 after SPS and the increase of the P2X3 expression was maintained on day 14 and 21 compared with controls. The P2X3-receptor agonist α,β-me ATP (10 μM) induced a fast desensitizing inward current in DRG neurons of both control and SPS-treated rats. The average peak current densities in SPS-treated group were increased 3.6-fold. TNP-ATP (100 nM) markedly blocked all fast α,β-me ATP-induced inward currents in the DRG neurons both in control and SPS-treated rats.

CONCLUSIONS & INFERENCES

The data indicate an important role of P2X3 signaling in visceral hyperalgesia following PTSD-like stress.

Potential neurobiological benefits of exercise in chronic pain and posttraumatic stress disorder: Pilot study

This pilot study assessed the effects of cardiopulmonary exercise testing and cardiorespiratory fitness on plasma neuropeptide Y (NPY), allopregnanolone and pregnanolone (ALLO), cortisol, and dehydroepiandrosterone (DHEA), and their association with pain sensitivity. Medication-free trauma-exposed participants were either healthy (n = 7) or experiencing comorbid chronic pain/posttraumatic stress disorder (PTSD) (n = 5). Peak oxygen consumption (VO2) during exercise testing was used to characterize cardiorespiratory fitness. Peak VO2 correlated with baseline and peak NPY levels (r = 0.66, p < 0.05 and r = 0.69, p < 0.05, respectively), as well as exercise-induced changes in ALLO (r = 0.89, p < 0.001) and peak ALLO levels (r = 0.71, p < 0.01). NPY levels at the peak of exercise correlated with pain threshold 30 min after exercise (r = 0.65, p < 0.05), while exercise-induced increases in ALLO correlated with pain tolerance 30 min after exercise (r = 0.64, p < 0.05). In contrast, exercise-induced changes in cortisol and DHEA levels were inversely correlated with pain tolerance after exercise (r = -0.69, p < 0.05 and r = -0.58, p < 0.05, respectively). These data suggest that cardiorespiratory fitness is associated with higher plasma NPY levels and increased ALLO responses to exercise, which in turn relate to pain sensitivity. Future work will examine whether progressive exercise training increases cardiorespiratory fitness in association with increases in NPY and ALLO and reductions in pain sensitivity in chronic pain patients with PTSD.

Allopregnanolone Levels Are Inversely Associated with Self-Reported Pain Symptoms in U.S. Iraq and Afghanistan-Era Veterans: Implications for Biomarkers and Therapeutics

BACKGROUND AND OBJECTIVES

Pain symptoms are common among Iraq/Afghanistan-era veterans, many of whom continue to experience persistent pain symptoms despite multiple pharmacological interventions. Preclinical data suggest that neurosteroids such as allopregnanolone demonstrate pronounced analgesic properties, and thus represent logical biomarker candidates and therapeutic targets for pain. Allopregnanolone is also a positive GABAA receptor modulator with anxiolytic, anticonvulsant, and neuroprotective actions in rodent models. We previously reported inverse associations between serum allopregnanolone levels and self-reported pain symptom severity in a pilot study of 82 male veterans.

METHODS

The current study investigates allopregnanolone levels in a larger cohort of 485 male Iraq/Afghanistan-era veterans to attempt to replicate these initial findings. Pain symptoms were assessed by items from the Symptom Checklist-90-R (SCL-90-R) querying headache, chest pain, muscle soreness, and low back pain over the past 7 days. Allopregnanolone levels were quantified by gas chromatography/mass spectrometry.

RESULTS

Associations between pain ratings and allopregnanolone levels were examined with Poisson regression analyses, controlling for age and smoking. Bivariate nonparametric Mann–Whitney analyses examining allopregnanolone levels across high and low levels of pain were also conducted. Allopregnanolone levels were inversely associated with muscle soreness [P = 0.0028], chest pain [P = 0.032], and aggregate total pain (sum of all four pain items) [P = 0.0001]. In the bivariate analyses, allopregnanolone levels were lower in the group reporting high levels of muscle soreness [P = 0.001].

CONCLUSIONS

These findings are generally consistent with our prior pilot study and suggest that allopregnanolone may function as an endogenous analgesic. Thus, exogenous supplementation with allopregnanolone could have therapeutic potential. The characterization of neurosteroid profiles may also have biomarker utility.

Clinical outcomes of Botox injections for chronic temporomandibular disorders: do we understand how Botox works on muscle, pain, and the brain?

The main objective of this retrospective review was to analyze the clinical outcomes following the use of botulinum toxin (onabotulinumtoxinA, Botox) injections to relieve the symptoms of chronic temporomandibular disorders (TMD). Seventy-one patients with a diagnosis of TMD (according to the RDC/TMD international consortium) associated with or without bruxism and refractory to conventional treatment (e.g. oral appliances, physiotherapy, etc.) received Botox injections into the temporalis and masseter muscles. Subjective responses to Botox were categorized as 'beneficial' or 'not beneficial', as patient-reported outcomes based on the subjective reduction in pain and/or improvement in function. Fifty-five of the 71 subjects (77%) reported beneficial effects with Botox. Subjects with a concomitant bruxism diagnosis reported significant improvement over subjects without bruxism (87% vs. 67%; P=0.042). Subjects with stress-related psychiatric comorbidities and bruxism had a significantly higher benefit than those with stress-related psychiatric comorbidities alone (P=0.027). Patients reported less improvement if the time between the initial Botox injection and follow-up was less than an average of 5 weeks, compared to an average follow-up of 5-10 weeks (P=0.009). The subgroup TMD diagnosis and time interval post-injection are important predictors of patient-reported beneficial outcomes.

Hippocampal activation of microglia may underlie the shared neurobiology of comorbid posttraumatic stress disorder and chronic pain

The high comorbidity rates of posttraumatic stress disorder and chronic pain have been widely reported, but the underlying mechanisms remain unclear. Emerging evidence suggested that an excess of inflammatory immune activities in the hippocampus involved in the progression of both posttraumatic stress disorder and chronic pain. Considering that microglia are substrates underlying the initiation and propagation of the neuroimmune response, we hypothesized that stress-induced activation of hippocampal microglia may contribute to the pathogenesis of posttraumatic stress disorder-pain comorbidity. We showed that rats exposed to single prolonged stress, an established posttraumatic stress disorder model, exhibited persistent mechanical allodynia and anxiety-like behavior, which were accompanied by increased activation of microglia and secretion of pro-inflammatory cytokines in the hippocampus. Correlation analyses showed that hippocampal activation of microglia was significantly correlated with mechanical allodynia and anxiety-like behavior. Our data also showed that both intraperitoneal and intra-hippocampal injection of minocycline suppressed single prolonged stress-induced microglia activation and inflammatory cytokines accumulation in the hippocampus, and attenuated both single prolonged stress-induced mechanical allodynia and anxiety-like behavior. Taken together, the present study suggests that stress-induced microglia activation in the hippocampus may serve as a critical mechanistic link in the comorbid relationship between posttraumatic stress disorder and chronic pain. The novel concept introduces the possibility of cotreating chronic pain and posttraumatic stress disorder.

Treatment-refractory posttraumatic stress disorder (TRPTSD): a review and framework for the future

Post-traumatic stress disorder (PTSD) is a serious psychiatric consequence of trauma that occurs in a proportion of individuals exposed to life-threatening events. Trauma-focused psychotherapy is often recommended as first choice for those who do not recover spontaneously. But many individuals require medications. In the US, only paroxetine (PRX) and sertraline (SRT) are FDA approved for PTSD. But response and remission rates with these medications are low, so numerous other pharmacologic interventions have been tried. To date, there has not been a systematic review of the data on what are the best next-step pharmacologic strategies for individuals who fail standard treatments. To that end, we review 168 published trials of medications other than PRX or SRT and provide a detailed analysis of the 88/168 studies that describe alternative pharmacologic interventions in patients refractory to other treatment. We also review clinical factors relevant to treatment-refractory PTSD; the neurobiology of extinction, as well as evidence-based psychotherapy and neuromodulation strategies for this condition.

Altered Pain Perception and Fear-Learning Deficits in Subjects With Posttraumatic Stress Disorder

There is growing evidence that fear-learning abnormalities are involved in the development of posttraumatic stress disorder (PTSD) and chronic pain. More than 50% of PTSD patients suffer from chronic pain. This study aimed to examine the role of fear-learning deficits in the link between pain perception and PTSD. We included 19 subjects with PTSD and 21 age- and sex-matched healthy control subjects in a fear-conditioning experiment. The conditioned stimulus (CS) consisted of visual signs flashed upon a screen in front of each subject. The unconditioned stimulus was either a low or high temperature impulse delivered through a thermal contact thermode on the subjects' hand. A designation of 'CS-' was assigned to CS always followed by nonpainful low-temperature stimuli; a designation of 'CS+' was given to CS that were randomly followed by either a low or a more painful high temperature. Skin conductance was used as a physiological marker of fear. In healthy control subjects, CS+ induced more fear than CS-, and a low-temperature stimulus induced less subjective pain after CS- than after CS+. PTSD subjects failed to demonstrate such adaptive conditioning. Fear ratings after CS presentation were significantly higher in the PTSD group than in the control group. There were significant interaction effects between group and the type of CS on fear and pain ratings. Fear-learning deficits are a potentially promising, specific psychopathological factor in altered pain perception associated with PTSD. Deficits in safety learning may increase fear and, consequently, pain sensations. These findings may contribute to elucidating the pathogenesis behind the highly prevalent comorbidity that exists between PTSD and pain disorders, and to developing new treatments.

PERSPECTIVE

This study provides new insights into the pathogenesis of chronic pain in patients with PTSD. The findings may help to develop new treatment strategies for this highly prevalent comorbidity in PTSD.

Depression and dissociation as predictors of physical health symptoms among female rape survivors with posttraumatic stress disorder

OBJECTIVE

To investigate the relative contributions of depression and dissociation, as well as posttraumatic stress disorder (PTSD), to physical health symptoms and to examine the relationships among somatic symptoms, PTSD, depression, and dissociation in relation to childhood and adult trauma exposure.

METHOD

Cross-sectional data are from 132 female rape survivors with PTSD assessed before engaging in a study of trauma-focused cognitive therapy for PTSD. Measures included the Pennebaker Inventory of Limbic Languidness, Clinician Administered PTSD Scale, Beck Depression Inventory, Trauma Symptom Inventory-Dissociation Subscale, Childhood Sexual Abuse Exposure Questionnaire, and Assessing Environments-III-Physical Punishment Scale.

RESULTS

Hierarchical regression analyses revealed that only dissociative and depression symptoms contributed significantly to physical health symptoms. Similarly, among the subsample of women with either childhood sexual or physical abuse, depression and dissociation were significant predictors of somatic symptoms. However, among women without childhood abuse, only dissociation significantly predicted somatic symptoms.

CONCLUSION

Understanding the psychological and biological mechanisms that link childhood versus adult trauma exposure, PTSD, and comorbid depression or dissociation to physical health symptoms may aid development of individualized treatments for the physical and psychological consequences of trauma. (PsycINFO Database Record

Symptoms of PTSD Associated With Painful and Nonpainful Vicarious Reactivity Following Amputation

Although the experience of vicarious sensations when observing another in pain have been described postamputation, the underlying mechanisms are unknown. We investigated whether vicarious sensations are related to posttraumatic stress disorder (PTSD) symptoms and chronic pain. In Study 1, 236 amputees completed questionnaires about phantom limb phenomena and vicarious sensations to both innocuous and painful sensory experiences of others. There was a 10.2% incidence of vicarious sensations, which was significantly more prevalent in amputees reporting PTSD-like experiences, particularly increased arousal and reexperiencing the event that led to amputation (φ = .16). In Study 2, 63 amputees completed the Empathy for Pain Scale and PTSD Checklist-Civilian Version. Cluster analyses revealed 3 groups: 1 group did not experience vicarious pain or PTSD symptoms, and 2 groups were vicarious pain responders, but only 1 had increased PTSD symptoms. Only the latter group showed increased chronic pain severity compared with the nonresponder group (p = .025) with a moderate effect size (r = .35). The findings from both studies implicated an overlap, but also divergence, between PTSD symptoms and vicarious pain reactivity postamputation. Maladaptive mechanisms implicated in severe chronic pain and physical reactivity posttrauma may increase the incidence of vicarious reactivity to the pain of others.

Longitudinal Study of Headache Trajectories in the Year After Mild Traumatic Brain Injury: Relation to Posttraumatic Stress Disorder Symptoms

OBJECTIVE

To examine headache trajectories among persons with mild traumatic brain injury (MTBI) in the year after injury and the relation of headache trajectory to posttraumatic stress disorder (PTSD) at 1 year postinjury.

DESIGN

Prospective, longitudinal study.

SETTING

Participants were recruited through a university medical center and participated in follow-up assessments by telephone.

PARTICIPANTS

Prospectively enrolled individuals (N=212) within 1 week of MTBI who were hospitalized for observation or other system injuries. Participants were assessed at baseline and 3, 6, and 12 months postinjury.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Participants rated average headache pain intensity using the 0 to 10 numerical rating scale at each assessment period. The PTSD Checklist-Civilian Version was completed at 12 months postinjury.

RESULTS

Latent class growth analysis produced a 4-trajectory group model, with groups labeled resolved, worsening, improving, and chronic. Multivariate regression modeling revealed that younger age and premorbid headache correlated with membership in the worse trajectory groups (worsening and chronic; P<.001). Univariate regression revealed a significant association between PTSD and membership in the worse trajectory groups (P<.001).

CONCLUSIONS

Headache is common in the year after MTBI, with younger people, persons who previously had headaches, and persons with PTSD more likely to report chronic or worsening headache. Further research is needed to examine whether PTSD symptoms exacerbate headaches or whether problematic headache symptoms exacerbate PTSD.

Ganaxolone improves behavioral deficits in a mouse model of post-traumatic stress disorder

Allopregnanolone and its equipotent stereoisomer, pregnanolone (together termed ALLO), are neuroactive steroids that positively and allosterically modulate the action of gamma-amino-butyric acid (GABA) at GABA_A receptors. Levels of ALLO are reduced in the cerebrospinal fluid of female premenopausal patients with post-traumatic stress disorder (PTSD), a severe, neuropsychiatric condition that affects millions, yet is without a consistently effective therapy. This suggests that restoring downregulated brain ALLO levels in PTSD may be beneficial. ALLO biosynthesis is also decreased in association with the emergence of PTSD-like behaviors in socially isolated (SI) mice. Similar to PTSD patients, SI mice also exhibit changes in the frontocortical and hippocampal expression of GABA_A receptor subunits, resulting in resistance to benzodiazepine-mediated sedation and anxiolysis. ALLO acts at a larger spectrum of GABA_A receptor subunits than benzodiazepines, and increasing corticolimbic ALLO levels in SI mice by injecting ALLO or stimulating ALLO biosynthesis with a selective brain steroidogenic stimulant, such as S-norfluoxetine, at doses far below those that block serotonin reuptake, reduces PTSD-like behavior in these mice. This suggests that synthetic analogs of ALLO, such as ganaxolone, may also improve anxiety, aggression, and other PTSD-like behaviors in the SI mouse model. Consistent with this hypothesis, ganaxolone (3.75–30 mg/kg, s.c.) injected 60 min before testing of SI mice, induced a dose-dependent reduction in aggression toward a same-sex intruder and anxiety-like behavior in an elevated plus maze. The EC₅₀ dose of ganaxolone used in these tests also normalized exaggerated contextual fear conditioning and, remarkably, enhanced fear extinction retention in SI mice. At these doses, ganaxolone failed to change locomotion in an open field test. Therefore, unlike benzodiazepines, ganaxolone at non-sedating concentrations appears to improve dysfunctional emotional behavior associated with deficits in ALLO in mice and may provide an alternative treatment for PTSD patients with deficits in the synthesis of ALLO. Selective serotonin reuptake inhibitors (SSRIs) are the only medications currently approved by the FDA for treatment of PTSD, although they are ineffective in a substantial proportion of PTSD patients. Hence, an ALLO analog such as ganaxolone may offer a therapeutic GABAergic alternative to SSRIs for the treatment of PTSD or other disorders in which ALLO biosynthesis may be impaired.