Cortisol, learning, memory, and attention in relation to smaller hippocampal volume in police officers with posttraumatic stress disorder

Relations of Lifetime Perceived Stress and Basal Cortisol With Hippocampal Volume Among Healthy Adolescents and Those at Clinical High Risk for Psychosis: A Structural Equation Modeling Approach

BACKGROUND

Hippocampal volume (HV) is sensitive to environmental influences. Under normative conditions in humans, HV increases linearly into childhood and asymptotes in early adulthood. Studies of humans and nonhuman animals have provided evidence of inverse relationships between several measures of stress and HV.

METHODS

Using structural equation modeling, this study aimed to characterize the relationships of age, basal cortisol, biological sex, and lifetime perceived stress with bilateral HV in a sample of healthy adolescents and adolescents at clinical high risk for psychosis (CHR-P) (N = 571, 43% female; age range = 12-19.9 years). This sample included 469 individuals at CHR-P and 102 healthy comparison participants from the combined baseline cohorts of the second and third NAPLS (North American Prodrome Longitudinal Study).

RESULTS

A structural model that constrained the individual effects of basal cortisol and perceived stress to single path coefficients, and freely estimated the effects of age and biological sex in group models, optimized model fit and parsimony relative to other candidate models. Significant inverse relationships between basal cortisol and bilateral HV were observed in adolescents at CHR-P and healthy comparison participants. Significant sex differences in bilateral HV were also observed, with females demonstrating smaller HV than males in both groups.

CONCLUSIONS

Multigroup structural equation modeling revealed heterogeneity in the relationships of age and biological sex with basal cortisol, lifetime perceived stress, and bilateral HV in individuals at CHR-P and healthy comparison participants. Moreover, the findings support previous literature indicating that elevated basal cortisol is a nonspecific risk factor for reduced HV.

Childhood urbanicity is associated with emotional episodic memory-related striatal function and common variation in NTRK2

BACKGROUND

Childhoods in urban or rural environments may differentially affect the risk of neuropsychiatric disorders, possibly through memory processing and neural response to emotional stimuli. Genetic factors may not only influence individuals' choices of residence but also modulate how the living environment affects responses to episodic memory.

METHODS

We investigated the effects of childhood urbanicity on episodic memory in 410 adults (discovery sample) and 72 adults (replication sample) with comparable socioeconomic statuses in Beijing, China, distinguishing between those with rural backgrounds (resided in rural areas before age 12 and relocated to urban areas at or after age 12) and urban backgrounds (resided in cities before age 12). We examined the effect of childhood urbanicity on brain function across encoding and retrieval sessions using an fMRI episodic memory paradigm involving the processing of neutral or aversive pictures. Moreover, genetic association analyses were conducted to understand the potential genetic underpinnings that might contribute to memory processing and neural mechanisms influenced by early-life urban or rural environments.

RESULTS

Episodic memory retrieval accuracy for more difficult neutral stimuli was similar between those with urban and rural childhoods, whereas aversive stimuli elicited higher retrieval accuracy in the urban group (P = 0.023). For aversive stimuli, subjects with urban childhood had relatively decreased engagement of the striatum at encoding and decreased engagement of the hippocampus at retrieval. This more efficient striatal encoding of aversive stimuli in those with urban childhoods was associated with common variation in neurotrophic tyrosine kinase receptor type 2 (NTRK2) (right striatum: P = 1.58×10-6). These findings were confirmed in the replication sample.

CONCLUSIONS

We suggest that this differential striatal processing of aversive stimuli observed in individuals with urban or rural childhoods may represent mechanisms by which childhood urbanicity may affect brain circuits, heightening behavioral responses to negative stressors associated with urban environments. NTRK2-associated neural processes in the striatum may play a role in these processes.

Trauma-related intrusive memories and anterior hippocampus structural covariance: an ecological momentary assessment study in posttraumatic stress disorder

Trauma-related intrusive memories (TR-IMs) are hallmark symptoms of posttraumatic stress disorder (PTSD), but their neural correlates remain partly unknown. Given its role in autobiographical memory, the hippocampus may play a critical role in TR-IM neurophysiology. The anterior and posterior hippocampi are known to have partially distinct functions, including during retrieval of autobiographical memories. This study aimed to investigate the relationship between TR-IM frequency and the anterior and posterior hippocampi morphology in PTSD. Ninety-three trauma-exposed adults completed daily ecological momentary assessments for fourteen days to capture their TR-IM frequency. Participants then underwent anatomical magnetic resonance imaging to obtain measures of anterior and posterior hippocampal volumes. Partial least squares analysis was applied to identify a structural covariance network that differentiated the anterior and posterior hippocampi. Poisson regression models examined the relationship of TR-IM frequency with anterior and posterior hippocampal volumes and the resulting structural covariance network. Results revealed no significant relationship of TR-IM frequency with hippocampal volumes. However, TR-IM frequency was significantly negatively correlated with the expression of a structural covariance pattern specifically associated with the anterior hippocampus volume. This association remained significant after accounting for the severity of PTSD symptoms other than intrusion symptoms. The network included the bilateral inferior temporal gyri, superior frontal gyri, precuneus, and fusiform gyri. These novel findings indicate that higher TR-IM frequency in individuals with PTSD is associated with lower structural covariance between the anterior hippocampus and other brain regions involved in autobiographical memory, shedding light on the neural correlates underlying this core symptom of PTSD.

Hypothalamus volume mediates the association between adverse childhood experience and PTSD development after adulthood trauma

The hypothalamus is critical for regulation of the hypothalamic-pituitary-adrenal (HPA) axis and response to stress. Adverse childhood experience (ACE) can affect brain structure, which may contribute to development of posttraumatic stress disorder (PTSD) after subsequent adult trauma. It is unclear, however, if ACE history is particularly associated with aspects of hypothalamic structure which contribute to development of PTSD. To address this issue, the present study longitudinally assessed hypothalamic volumes and their associations with ACE and early post-trauma stress symptoms in subjects who did or did not develop PTSD during 12 months after adult trauma. 109 subjects (18-60 years, F/M = 75/34) completed the PTSD Checklist (PCL) questionnaire for post-trauma stress symptoms, the Childhood Trauma Questionnaire (CTQ) for ACE assessment, and an initial MRI brain scan for hypothalamic volume measurement, within 2 weeks after adult trauma. At post-trauma 12 months, subjects underwent a subsequent PTSD diagnosis interview using the Clinician-Administered PTSD Scale (CAPS), and a follow-up MRI scan. Left and right hypothalamus volumes at 2 weeks after adult trauma negatively correlated with CTQ scores. Right hypothalamus volume at this early time mediated an association between ACE and PTSD symptoms 12 months later. Right hypothalamus volumes also remained persistently smaller from 2 weeks to 12 months after trauma in survivors who developed PTSD. These results suggest that smaller right hypothalamus volume may be related to ACE history in ways that contribute to PTSD development after trauma in adulthood.

Bilateral eye movements disrupt the involuntary perceptual representation of trauma-related memories

Bilateral eye movement (EM) is a critical component in eye movement desensitization and reprocessing (EMDR), an effective treatment for post-traumatic stress disorder. However, the role of bilateral EM in alleviating trauma-related symptoms is unclear. Here we hypothesize that bilateral EM selectively disrupts the perceptual representation of traumatic memories. We used the trauma film paradigm as an analog for trauma experience. Nonclinical participants viewed trauma films followed by a bilateral EM intervention or a static Fixation period as a control. Perceptual and semantic memories for the film were assessed with different measures. Results showed a significant decrease in perceptual memory recognition shortly after the EM intervention and subsequently in the frequency and vividness of film-related memory intrusions across one week, relative to the Fixation condition. The EM intervention did not affect the explicit recognition of semantic memories, suggesting a dissociation between perceptual and semantic memory disruption. Furthermore, the EM intervention effectively reduced psychophysiological affective responses, including the skin conductance response and pupil size, to film scenes and subjective affective ratings of film-related intrusions. Together, bilateral EMs effectively reduce the perceptual representation and affective response of trauma-related memories. Further theoretical developments are needed to elucidate the mechanism of bilateral EMs in trauma treatment.

The influence of the BDNF Val66Met genotype on emotional recognition memory in post-traumatic stress disorder

Dysregulated consolidation of emotional memories is a core feature of posttraumatic stress disorder (PTSD). Brain Derived Neurotrophic Factor (BDNF) influences synaptic plasticity and emotional memory consolidation. The BDNF Val66Met polymorphism has been associated with PTSD risk and memory deficits respectively, although findings have been inconsistent, potentially due to a failure to control for important confounds such as sex, ethnicity, and the timing/extent of previous trauma experiences. Furthermore, very little research has examined the impact of BDNF genotypes on emotional memory in PTSD populations. This study investigated the interaction effects of Val66Met and PTSD symptomatology in an emotional recognition memory task in 234 participants divided into healthy control (n = 85), trauma exposed (TE: n = 105) and PTSD (n = 44) groups. Key findings revealed impaired negative recognition memory in PTSD compared to control and TE groups and in participants with the Val/Met compared to the Val/Val genotype. There was a group × genotype interaction showing no Met effect in the TE group despite significant effects in PTSD and controls. Results suggest that people previously exposed to trauma who do not develop PTSD may be protected from the BDNF Met effect, however more research is needed to replicate findings and to explore the epigenetic and neural processes involved.

Attention deficits as a key player in the symptomatology of posttraumatic stress disorder: A review

Posttraumatic stress disorder (PTSD) is a debilitating psychiatric disorder characterized by symptoms such as re-experiencing of the psychotrauma and hyperarousal. Although current literature mainly discusses the emotionally related aspects of these symptoms, studies also highlight the relation between re-experiencing, hyperarousability, and attention deficits, which are associated with poorer daily function and reduced quality of life. This review provides a comprehensive analysis of the existing research on attention deficits among adults with PTSD. A systematic search through five databases resulted in the inclusion of 48 peer-reviewed, English-language articles, describing 49 distinct studies. Using a total of 47 different attentional assessment tools, the majority of studies investigated sustained (n = 40), divided (n = 16), or selective (n = 14) attention. A total of 30 studies (61.2%) found significant correlations between PTSD symptoms and attention deficits, and 10 studies (20.4%) found that higher levels of attention deficits were predictive of worse PTSD symptoms. Moreover, neuroimaging results of six (f)MRI and three EEG studies identified various potential neurobiological pathways involved, including (pre)frontal attention networks. Together, the body of research shows that attention deficits in individuals with PTSD are common and occur in surroundings with emotionally neutral stimuli. Nonetheless, current treatment strategies do not target these attentional difficulties. We propose a novel perspective to PTSD diagnosis and treatment strategies based on attention deficits and their relation with top-down regulation of re-experiencing and subsequent other PTSD symptoms.

Astrocytes in Post-traumatic Stress Disorder

Although posttraumatic stress disorder (PTSD) is on the rise, traumatic events and their consequences are often hidden or minimized by patients for reasons linked to PTSD itself. Traumatic experiences can be broadly classified into mental stress (MS) and traumatic brain injury (TBI), but the cellular mechanisms of MS- or TBI-induced PTSD remain unknown. Recent evidence has shown that the morphological remodeling of astrocytes accompanies and arguably contributes to fearful memories and stress-related disorders. In this review, we summarize the roles of astrocytes in the pathogenesis of MS-PTSD and TBI-PTSD. Astrocytes synthesize and secrete neurotrophic, pro- and anti-inflammatory factors and regulate the microenvironment of the nervous tissue through metabolic pathways, ionostatic control, and homeostatic clearance of neurotransmitters. Stress or trauma-associated impairment of these vital astrocytic functions contribute to the pathophysiological evolution of PTSD and may present therapeutic targets.

The Impact of Electroacupuncture Early Intervention on the Brain Lipidome in a Mouse Model of Post-traumatic Stress Disorder

The neuroprotective effect of electroacupuncture (EA) treatment has been well studied; growing evidence suggests that changes in lipid composition may be involved in the pathogenesis of post-traumatic stress disorder (PTSD) and may be a target for treatment. However, the influence of early EA intervention on brain lipid composition in patients with PTSD has never been investigated. Using a modified single prolonged stress (mSPS) model in mice, we assessed the anti-PTSD-like effects of early intervention using EA and evaluated changes in lipid composition in the hippocampus and prefrontal cortex (PFC) using a mass spectrometry-based lipidomic approach. mSPS induced changes in lipid composition in the hippocampus, notably in the content of sphingolipids, glycerolipids, and fatty acyls. These lipid changes were more robust than those observed in the PFC. Early intervention with EA after mSPS ameliorated PTSD-like behaviors and partly normalized mSPS-induced lipid changes, notably in the hippocampus. Cumulatively, our data suggest that EA may reverse mSPS-induced PTSD-like behaviors due to region-specific regulation of the brain lipidome, providing new insights into the therapeutic mechanism of EA.

Impaired episodic memory in PTSD patients - A meta-analysis of 47 studies

Episodic memory impairments beyond the traumatic event might be a characteristic hallmark of post-traumatic stress disorder (PTSD). Although several studies support such a claim, empirical findings are inconsistent. Therefore, we performed a random-effects meta-analysis including data from a total of 47 studies and 3,062 subjects. As main finding, we can show that PTSD patients show episodic memory deficits compared to all controls. This effect was significantly stronger for PTSD vs. non-traumatized healthy controls as compared to PTSD vs. traumatized controls without PTSD. Finally, episodic memory impairments in PTSD were most pronounced in verbal memory tests as compared to non-verbal memory tests. Our results provide new evidence that PTSD is characterized by impaired episodic long-term memory beyond the traumatic event, and these deficits are particularly pronounced in verbal memory. We will discuss our findings in the context of physiological, psychological and trauma related memory models. From a broader perspective, our findings may have implications for the treatment of PTSD by suggesting that the assessment and, if necessary, training of memory deficits could be included as part of diagnostics and psychotherapeutic treatment.

The key to superior memory encoding under stress: the relationship between cortisol response and mnemonic discrimination

Some previous studies have shown that increased stress hormone levels have beneficial effects on memory encoding; however, there is no clear consensus on which encoding-related processes are affected by stress hormones. In the present study, we investigated the relationship between interindividual differences in neuroendocrine response to acute stress and interference resolution (i.e., mnemonic discrimination). Participants were healthy young adults who were exposed to physical and psychological stressors (Socially Evaluated Cold Pressor Test). Then participants completed the modified version of the Mnemonic Similarity Task. Specifically, they were presented with photographs of emotionally arousing (negative and positive) and nonarousing (neutral) scenes followed by a recognition memory test where they saw a mixture of old and new stimuli. Crucially, participants were also presented with critical lure items, that is, visually similar stimuli to ones presented at encoding. We found that participants who had higher cortisol response to the stressors were better in discriminating between the studied items and their visually similar lures. This effect was present for the arousing and nonarousing materials as well. These findings suggest that increased hormonal response to acute stress has a beneficial impact on the formation of distinct, nonoverlapping, unique memory representations, and consequently, on episodic memory encoding processes.

The environment contributes more than genetics to smaller hippocampal volume in Posttraumatic Stress Disorder (PTSD)

BACKGROUND

Studies using structural magnetic resonance imaging (MRI) volumetrics showed smaller hippocampal volume in patients with post-traumatic stress disorder (PTSD). These studies were cross-sectional and did not address whether smaller volume is secondary to stress-induced damage, or whether pre-existing factors account for the findings. The purpose of this study was to use a co-twin case control design to assess the relative contribution of genetic and environmental factors to hippocampal volume in PTSD.

METHODS

Monozygotic (N = 13 pairs) and dizygotic (N = 21 pairs) twins with a history of Vietnam Era military service, where one brother went to Vietnam and developed PTSD, while his brother did not go to Vietnam or develop PTSD, underwent MR imaging of the brain. Structural MRI scans were used to manually outline the left and right hippocampus on multiple coronal slices, add the areas and adjust for slice thickness to determine hippocampal volume.

RESULTS

Twins with Vietnam combat-related PTSD had a mean 11% smaller right hippocampal volume in comparison to their twin brothers without combat exposure or PTSD (p < .05). There was no significant interaction by zygosity, suggesting that this was not a predisposing risk factor or genetic effect.

CONCLUSIONS

These findings are consistent with smaller hippocampal volume in PTSD, and suggest that the effects are primarily due to environmental effects such as the stress of combat.

miR-132 Regulates PTSD-like Behaviors in Rats Following Single-Prolonged Stress Through Fragile X-Related Protein 1

Fragile X-related protein 1 (FXR1) is a member of the fragile X family of RNA-binding proteins, which regulates a number of neurological and neuropsychiatric disorders such as fragile X syndrome, and is expected as a novel therapeutic target for some psychiatric diseases. However, it is unknown how FXR1 changes and functions in post-traumatic stress disorder (PTSD), a common mental disorder related to trauma and stressor. In this study, we characterized the expression pattern of FXR1 in the pathophysiological process of PTSD and further investigated the possible mechanism underlying these changes by finding an upstream regulator, namely miRNA-132 (miR-132). Furthermore, we verified whether miR-132 silence had an effect on the PTSD-like behaviors of single prolonged stress (SPS) rats through open field test, forced swimming test, and water maze test. At last, we examined the expression levels of PSD95 and synapsin I in the hippocampus, which was one of the key brain regions associated with PTSD. We showed that the levels of FXR1 and fragile X mental retardation protein (FMRP), an autosomal homolog of FXR1, were decreased in the hippocampus of PTSD rats, but the levels of PSD95 and synapsin I were increased, which could be reversed by downregulation of miR-132. The results revealed that miR-132 could modulate PTSD-like behaviors in rats following SPS through regulating FXR1 and FMRP.

Induced pluripotent stem cell-derived neural progenitor cell transplantation promotes regeneration and functional recovery after post-traumatic stress disorder in rats

Post-traumatic stress disorder (PTSD) is a mental disorder characterized by hippocampal neuron loss and cognitive dysfunction. The aim of the present study was to investigate the potential functional outcomes of transplantation of induced pluripotent stem cell-derived neural progenitor cells (iPSC-NPCs) for treating PTSD. Human induced pluripotent stem cell (iPSCs), differentiated into neural progenitor cells (NPCs) in vitro, were transplanted into the brain of rat. Following iPSC-NPCs transplantation, cognitive function was determined. The open field test and fear condition test indicated that long-term iPSC-NPCs transplantation ameliorated cognitive dysfunction and reduced freezing time in PTSD rats. Following testing, the brain of rat was analyzed using immunocytochemistry and immunofluorescence. The results revealed that iPSC-NPCs differentiated into neurons replacing the loss of hippocampus neurons, and iPSC-NPCs transplantation showed higher expression of glial fibrillary acidic protein (GFAP) and increased number of NeuN compared with the control group. Moreover, western blot analysis suggested enhanced expression of brain-derived neurotrophic factor (BDNF) in hippocampus tissue of iPSC-NPCs transplanted rats in comparison to the PBS group. Collectively, these findings showed that iPSC-NPCs could promote regeneration and motor function recovery in PTSD model.

Trauma on duty: cognitive functioning in police officers with and without posttraumatic stress disorder (PTSD)

BACKGROUND

Neuropsychological alterations co-occur with Posttraumatic Stress Disorder (PTSD); yet, the nature and magnitude of such alterations in police officers remains unknown despite their high level of trauma exposure.

OBJECTIVE

The current research sought to examine (1) cognitive functioning among police officers with and without PTSD; (2) the clinical significance of their cognitive performance; and (3) the relationship between PTSD symptoms and cognition.

METHOD

Thirty-one police officers with PTSD were compared to thirty age- and sex-matched trauma-exposed officers without PTSD. Clinical assessment and self-report questionnaires established PTSD status. All participants underwent a neuropsychological evaluation.

RESULTS

Police officers with PTSD displayed lower cognitive performance across several domains, notably executive functioning, verbal learning and memory, and lexical access, compared to controls. The neuropsychological decrements in the PTSD group were mild compared to normative data, with average performances falling within normal limits. Among officers with PTSD, higher levels of intrusion symptoms were associated with reduced efficacy in executive functioning, as well as attention and working memory. Moreover, increased intrusion and avoidance symptoms were associated with slower information processing speed.

CONCLUSION

Considering that even mild subclinical cognitive difficulties may affect their social and occupational functioning, it appears important to integrate neuropsychological assessments in the clinical management of police officers diagnosed with PTSD.

A novel arousal-based individual screening reveals susceptibility and resilience to PTSD-like phenotypes in mice

Translational animal models for studying post-traumatic stress disorder (PTSD) are valuable for elucidating the poorly understood neurobiology of this neuropsychiatric disorder. These models should encompass crucial features, including persistence of PTSD-like phenotypes triggered after exposure to a single traumatic event, trauma susceptibility/resilience and predictive validity. Here we propose a novel arousal-based individual screening (AIS) model that recapitulates all these features. The AIS model was designed by coupling the traumatization (24 h restraint) of C57BL/6 J mice with a novel individual screening. This screening consists of z-normalization of post-trauma changes in startle reactivity, which is a measure of arousal depending on neural circuits conserved across mammals. Through the AIS model, we identified susceptible mice showing long-lasting hyperarousal (up to 56 days post-trauma), and resilient mice showing normal arousal. Susceptible mice further showed persistent PTSD-like phenotypes including exaggerated fear reactivity and avoidance of trauma-related cue (up to 75 days post-trauma), increased avoidance-like behavior and social/cognitive impairment. Conversely, resilient mice adopted active coping strategies, behaving like control mice. We further uncovered novel transcriptional signatures driven by PTSD-related genes as well as dysfunction of hypothalamic–pituitary–adrenal axis, which corroborated the segregation in susceptible/resilient subpopulations obtained through the AIS model and correlated with trauma susceptibility/resilience. Impaired hippocampal synaptic plasticity was also observed in susceptible mice. Finally, chronic treatment with paroxetine ameliorated the PTSD-like phenotypes of susceptible mice. These findings indicate that the AIS model might be a new translational animal model for the study of crucial features of PTSD. It might shed light on the unclear PTSD neurobiology and identify new pharmacological targets for this difficult-to-treat disorder.

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The AIS model includes highly requested features necessary to shape a translational PTSD animal model.

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Susceptible mice identified through the AIS model exhibited persistent PTSD-like phenotypes.

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Resilient mice identified through the AIS model adopted active coping strategies.

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The AIS model revealed molecular adaptations underlying trauma susceptibility/resilience.

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The AIS model meets the criterion of predictive validity by exclusively using susceptible mice.

Race, Ethnicity, Family Socioeconomic Status, and Children's Hippocampus Volume

Introduction

The hippocampus has a significant role in memory, learning, and cognition. Although hippocampal size is highly susceptible to family socioeconomic status (SES) and associated stress, very little is known on racial and ethnic group differences in the effects of SES indicators on hippocampus volume among American children.

Purpose

This study explored the multiplicative effects of race, ethnicity, and family SES on hippocampus volume among American children.

Methods

Using data from the Adolescent Brain Cognitive Development (ABCD), we analyzed the functional Magnetic Resonance Imaging (fMRI) data of 9390 9-10 years old children. The main outcome was hippocampus volume. The predictor was parental education. Subjective family SES was the independent variable. Age, sex, and marital status were the covariates. Racial and ethnic group membership were the moderators. To analyze the data, we used regression models.

Results

High subjective family SES was associated with larger hippocampus volume. This effect was significantly larger for Whites than Black families.

Conclusions

The effect of subjective family SES on children's hippocampus volume is weaker in Black than White families.

Hyper-Activation of mPFC Underlies Specific Traumatic Stress-Induced Sleep-Wake EEG Disturbances

Sleep disturbances have been recognized as a core symptom of post-traumatic stress disorders (PTSD). However, the neural basis of PTSD-related sleep disturbances remains unclear. It has been challenging to establish the causality link between a specific brain region and traumatic stress-induced sleep abnormalities. Here, we found that single prolonged stress (SPS) could induce acute changes in sleep/wake duration as well as short- and long-term electroencephalogram (EEG) alterations in the isogenic mouse model. Moreover, the medial prefrontal cortex (mPFC) showed persistent high number of c-fos expressing neurons, of which more than 95% are excitatory neurons, during and immediately after SPS. Chemogenetic inhibition of the prelimbic region of mPFC during SPS could specifically reverse the SPS-induced acute suppression of delta power (1–4 Hz EEG) of non-rapid-eye-movement sleep (NREMS) as well as most of long-term EEG abnormalities. These findings suggest a causality link between hyper-activation of mPFC neurons and traumatic stress-induced specific sleep–wake EEG disturbances.

Family Income Mediates the Effect of Parental Education on Adolescents' Hippocampus Activation During an N-Back Memory Task

Introduction: Hippocampus, a medial temporal lobe structure, has significant implications in memory formation and learning. Although hippocampus activity is believed to be affected by socioeconomic status (SES), limited knowledge exists on which SES indicators influence hippocampus function. Purpose: This study explored the separate and combined effects of three SES indicators, namely parental education, family income, and neighborhood income, on adolescents’ hippocampus activation during an N-Back memory task. As some of the effects of parental education may be through income, we also tested if the effect of parental education on hippocampus activation during our N-Back memory task is mediated by family or neighborhood income. Methods: The Adolescent Brain Cognitive Development (ABCD) study is a national multi-center investigation of American adolescents’ brain development. Functional magnetic resonance imaging (fMRI) data of a total sample of 3067 9–10-year-old adolescents were used. The primary outcome was left- hippocampus activation during the N-Back memory task (mean beta weight for N-Back run 1 2 back versus 0 back contrast in left hippocampus). The independent variable was parental education. Family income and neighborhood income were two possible mediators. Age, sex, and marital status were the covariates. To test mediation, we used hierarchical linear regression models first without and then with our mediators. Full mediation was defined according to Kenny. The Sobel test was used to confirm statistical mediation. Results: In the absence of family and neighborhood income in the model, higher parental educational attainment was associated with lower level of left hippocampus activation during the N-Back memory task. This effect was significant while age, sex, and marital status were controlled. The association between parental educational attainment and hippocampus activation during the N-Back memory task was no more significant when we controlled for family and neighborhood income. Instead, family income was associated with hippocampus activation during the N-Back memory task. These findings suggested that family income fully mediates the effect of parental educational attainment on left hippocampus activation during the N-Back memory task. Conclusions: The effect of parental educational attainment on adolescents’ hippocampus activation during an N-Back memory task is fully explained by family income. That means low family income is why adolescents with low-educated parents show highlighted hippocampus activation during an N-Back memory task. Given the central role of the hippocampus in learning and memory and as income is a modifiable factor by tax and economic policies, income-redistribution policies, fair taxation, and higher minimum wage may have implications for promotion of adolescent equality and social justice. There is a need to focus on family-level economic needs across all levels of neighborhood income.

Cognitive functioning in posttraumatic stress disorder before and after cognitive-behavioral therapy

Although substantial evidence suggests altered executive functioning and autobiographical memory in posttraumatic stress disorder (PTSD), the clinical significance of these findings remains unclear. Here, we investigated the effects of cognitive-behavioral therapy (CBT) on different aspects of cognitive functioning (working memory, interference susceptibility, conflict adaptation, autobiographical memory) in PTSD patients in a pre-post control group design with a nested cross-sectional element. Cross-sectional analyses at baseline were conducted on 58 PTSD patients, 39 traumatized (TC), and 45 non-traumatized controls (NTC). Intervention effects were investigated before and after 25 CBT sessions in 25 PTSD and 34 untreated NTC individuals assessed in parallel. At baseline, PTSD patients showed higher conflict adaptation than the NTC group and less autobiographical memory specificity than both control groups, suggesting particularly the latter to be a correlate of PTSD. No consistent evidence for treatment-induced improvements in cognitive functioning emerged on the group level or from associations between intra-individual clinical and cognitive changes. Analyses on the role of cognitive functioning on subsequent treatment effects revealed a predictive effect of backward digit span on CBT-induced reductions of depressiveness, but no other significant effects. Our findings highlight the need for further research to identify more relevant predictors of differential treatment response.

Neuropsychological Impact of Trauma-Related Mental Illnesses: A Systematic Review of Clinically Meaningful Results

A trauma history is present in approximately 90% of adults in the United States. Comparatively, lifetime post-traumatic stress disorder (PTSD) prevalence is only 8.3% (Kilpatrick et al. Journal of Traumatic Stress, 26, 537-547, 2013). A neuropsychological understanding of trauma is essential to effective trauma-informed assessments and treatments. Prior reviews have focused on PTSD, specific neuropsychological domains, and statistically rather than clinically significant results. The current systematic review investigated standardized test performance across neuropsychological domains in participants with trauma histories and any psychiatric diagnosis. The review was conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. From 2350 records, the search returned 21 eligible studies: 8 for combat trauma, 2 for childhood trauma, 2 for intimate partner violence and sexual assault, 2 for accidental trauma, 1 for refugee trauma, and 6 for unspecified trauma. Mean neuropsychological scores ranged from low to high average, with one mean verbal memory score in the borderline range. These findings diverge from reports of between-group differences or experimental task performance, which suggest greater levels of static cognitive impairment. Current results are limited by lack of distinction between trauma types in the literature, a dearth of cognitive domains examined, wide use of self-report trauma measures, and publication and outcome reporting biases. Clinical implications for assessment and rehabilitation are discussed in relation to clinical significance, state versus trait based changes, intra-individual variability, changes from pre- to post-trauma, and within-group variability in resilience. Future directions are recommended in consideration of cultural factors, prospective and follow-up designs, and psychiatric diagnosis.

Investigating Individual Pre-trauma Susceptibility to a PTSD-Like Phenotype in Animals

Post-Traumatic Stress Disorder (PTSD) is a complex condition that develops after experiencing a severe emotional trauma, with or without physical trauma. There is no known cure and evidence-based treatments, which are effective in reducing symptoms, have low retention rates. It is therefore important, in addition to seeking new therapeutics, to identify ways to reduce the likelihood of developing PTSD. The fact that some, but not all, individuals exposed to the same traumatic event develop PTSD suggests that there is individual susceptibility. Investigating susceptibility and underlying factors will be better guided if there is a coherent framework for such investigations. In this review, we propose that susceptibility is a dynamic state that is comprised of susceptibility factors (before trauma) and sequalae factors (during or after trauma, but before PTSD diagnosis). We define key features of susceptibility and sequalae factors as: (1) they are detectable before trauma (susceptibility factors) or during/shortly after trauma (sequalae factors), (2) they can be manipulated, and (3) manipulation of these factors alters the likelihood of developing PTSD, thus affecting resilience. In this review we stress the importance of investigating susceptibility to PTSD with appropriate animal models, because prospective human studies are expensive and manipulation of susceptibility and sequalae factors for study purposes may not always be feasible. This review also provides a brief overview of a subset of animal models that study PTSD-related behaviors and related alterations in endocrine and brain systems that focus on individual differences, peri- and post-trauma. Attention is drawn to the RISP model (Revealing Individual Susceptibility to a PTSD-like Phenotype) which assesses susceptibility before trauma. Using the RISP model and expression of plasticity-associated immediate early genes, Arc and Homer1a, we have identified impaired hippocampal function as a potential susceptibility factor. We further discuss other putative susceptibility factors and approaches to mitigate them. We assert that this knowledge will guide successful strategies for interventions before, during or shortly after trauma that can decrease the probability of developing PTSD.

Allocentric spatial memory performance predicts intrusive memory severity in posttraumatic stress disorder

BACKGROUND

Posttraumatic stress disorder (PTSD) is characterized by distressing trauma-related memories. According to the dual representation theory, intrusive memories arise from strengthened egocentric encoding and a poor contextual encoding, with spatial context requiring allocentric processing. Contextualization of mental imagery is proposed to be formed hierarchically through the ventral visual stream (VVS) to the hippocampal formation. Here, we tested this notion by investigating whether neuronal aberrations in structures of the VVS or in the hippocampus, as well as allocentric memory performance are associated with intrusive memory severity.

METHODS

The sample comprised 33 women with PTSD due to childhood trauma. Allocentric memory performance was measured with the virtual Town Square Task and T1-weighted images acquired on a 3T Siemens Scanner. Intrusive memories were evoked by presenting an audio script describing parts of their trauma (script-driven imagery).

RESULTS

Using hierarchical linear regression analysis, we found a significant association between lower intrusive memory severity and higher allocentric spatial memory, controlling for age, working memory, and general visuospatial ability. No significant association was found between cortical thickness of VVS structures, hippocampal volume and intrusive memory severity. Post hoc exploratory analyses revealed a negative correlation between years since index trauma and left hippocampal volume.

LIMITATIONS

Our results are based on correlational analyses, causality cannot be inferred.

CONCLUSION

This study supports the dual representation theory, which emphasizes the role of allocentric spatial memory for the contextualization of mental imagery in PTSD. Clinical implications are discussed.

Early intervention with electroacupuncture prevents PTSD-like behaviors in rats through enhancing hippocampal endocannabinoid signaling

Electroacupuncture (EA) is a clinically useful physiological therapy that has been recently adopted to treat several brain disorders. However, the potential role of early EA intervention in the prevention of posttraumatic stress disorder (PTSD) as well as its potential cellular and molecular mechanism has never been investigated previously. In the present study, we used an enhanced single prolonged stress (ESPS) model to access the effects of early EA intervention on the prevention of anxiety-like and fear learning behaviors, as well as the influence of the expression of post-synaptic density protein 95 (PSD95), synaptophysin (Syn), brain derived neurotrophic factor (BDNF), diacylglycerol lipase alpha (DAGLα) and cannabinoid type 1 receptor (CB1R) in the hippocampus with or without DAGLα or CB1R knockdown by a short hairpin RNA (shRNA) in the hippocampus. Moreover, the effects of electrical stimulation with different parameters on the expression of DAGLα and CB1R in the hippocampal astrocytes were also observed. The results showed that Early EA intervention improved hippocampal synaptic plasticity and ameliorated PTSD-like behaviors and also increased expression of BDNF, DAGLα and CB1R. However, either DAGLα or CB1R knockdown by a short hairpin RNA (shRNA) eliminated the neuroprotective effects of early EA intervention. Furthermore, electrical stimulation with 2/15 Hz 1 mA elevated the expression of DAGLα and CB1R. Altogether, our findings provide new insights regarding the possibility of using early EA intervention in the prevention of PTSD, and the protective effects of EA is involving the activation of DAGLα and CB1R.

Neurocognition in PTSD: Treatment Insights and Implications

Post-traumatic stress disorder (PTSD) is classified as a traumatic stress-related condition and is most often discussed in terms of emotional dysfunction. However, given that cognitive and emotional processes are intricately intertwined, implemented by overlapping brain networks, and effectively integrated in at least some of the same regions (e.g., prefrontal cortex, for a review, see Crocker et al. 2013), an abundance of literature now highlights the key role that cognitive functioning plays in both the development and maintenance (or exacerbation) of PTSD symptoms (Aupperle et al. 2012a; Verfaellie et al. 2012). Findings from this body of work detail objective impairment in neuropsychological function in those with PTSD (Brandes et al. 2002; Hayes et al. 2012a; Koenen et al. 2001). Yet despite the impact of neurocognition on PTSD treatment engagement and success (e.g., Haaland et al. 2016; Nijdam et al. 2015) and conversely, the role of PTSD treatment in normalizing cognitive dysfunction, a much smaller literature exists on neurocognitive changes following treatment for PTSD. Even aside from its role in treatment, cognitive functioning in PTSD has significant implications for daily functioning for individuals with this disorder, as cognition is predictive of school achievement, obtaining and maintaining employment, job advancement, maintaining relationships, greater wealth, and better health and quality of life (e.g., Diamond and Ling 2016).

Rapid eye movement fragmentation, not slow-wave sleep, predicts neutral declarative memory consolidation in posttraumatic stress disorder

Individuals diagnosed with posttraumatic stress disorder (PTSD) experience disruption at both slow-wave sleep (SWS) and rapid-eye movement (REM) sleep stages and demonstrate marked memory impairment. A small group of studies suggests that, within the disorder, there is a mechanistic relation between these sleep and memory impairments. This study sought to extend that literature by examining whether, in PTSD-diagnosed individuals, memory-retention deficits are present after a sleep-filled (but not after a wake-filled) delay (i.e., whether memory deficits can be traced to interruptions of sleep-dependent memory consolidation). Moreover, we investigated whether SWS- or REM-based disturbances, or both, contribute to retention deficits. We recruited participants into three groups: PTSD (n = 21), trauma-exposed non-PTSD (TE; n = 19) and healthy control (HC; n = 20). Using a crossover design, we assessed memory recall before and after an 8-hr period of polysomnography-monitored sleep and an 8-hr period of regular waking activity. PTSD-diagnosed participants retained less information than controls over the sleep-filled (but not wake-filled) delay. Furthermore, increased REM fragmentation predicted postsleep memory retention in PTSD-diagnosed individuals only. No SWS parameter was associated with or predictive of the amount of information retained postsleep. We conclude that specific REM-related changes in PTSD-diagnosed individuals affected sleep-dependent neutral declarative memory consolidation. Generally, these findings extend the literature suggesting that the co-occurrence of sleep and memory difficulties in PTSD is not accidental, but that these two symptom clusters are meaningfully related. Specifically, the study illustrates that subtle REM-related disruptions contribute most strongly to memory impairment in PTSD.

Salivary cortisol in post-traumatic stress disorder: a systematic review and meta-analysis

BACKGROUND

Studies investigating salivary cortisol level as susceptibility marker for post-traumatic stress disorder (PTSD) produced inconsistent results. The aim of this study was to compare salivary cortisol concentration levels in PTSD patients with those in controls by synthesizing published data.

METHODS

We did a systematic review, meta-analysis and meta-regression of studies comparing concentrations of salivary cortisol between patients with PTSD and controls. The electronic databases of PubMed, Embase, Web of Science and Psyc-ARTICLES were searched for relevant articles. A random-effects model with restricted maximum-likelihood estimator is used to synthesize the effect size (assessed by standardized mean difference).

RESULTS

A total of 784 articles were identified of which 22 were included in the final analysis. A trend of lower salivary cortisol levels was found in PTSD patients when compared with the controls (SMD = - 0.28, 95% CI-0.53;-0.04, p = 0.022). Subgroup analysis showed that the salivary cortisol levels were lower in patients with PTSD than in controls in studies conducted after 2007 or in studies using saliva samples collected in the morning.

CONCLUSIONS

The evidence from this meta-analysis supports that salivary samples collected in the morning consistently showed a lower salivary cortisol level in patients with PTSD than in controls, although whether salivary cortisol could be used as a diagnostic tool requires further research.

A Comprehensive Overview on Stress Neurobiology: Basic Concepts and Clinical Implications

Stress is recognized as an important issue in basic and clinical neuroscience research, based upon the founding historical studies by Walter Canon and Hans Selye in the past century, when the concept of stress emerged in a biological and adaptive perspective. A lot of research after that period has expanded the knowledge in the stress field. Since then, it was discovered that the response to stressful stimuli is elaborated and triggered by the, now known, stress system, which integrates a wide diversity of brain structures that, collectively, are able to detect events and interpret them as real or potential threats. However, different types of stressors engage different brain networks, requiring a fine-tuned functional neuroanatomical processing. This integration of information from the stressor itself may result in a rapid activation of the Sympathetic-Adreno-Medullar (SAM) axis and the Hypothalamus-Pituitary-Adrenal (HPA) axis, the two major components involved in the stress response. The complexity of the stress response is not restricted to neuroanatomy or to SAM and HPA axes mediators, but also diverge according to timing and duration of stressor exposure, as well as its short- and/or long-term consequences. The identification of neuronal circuits of stress, as well as their interaction with mediator molecules over time is critical, not only for understanding the physiological stress responses, but also to understand their implications on mental health.

Relationship of Hippocampal Volumes and Posttraumatic Stress Disorder Symptoms Over Early Posttrauma Periods

BACKGROUND

Smaller hippocampal volume is associated with more severe posttraumatic stress disorder (PTSD) symptoms years after traumatic experiences. Posttraumatic stress symptoms appear early following trauma, but the relationship between hippocampal volume and PTSD symptom severity during early posttrauma periods is not well understood. It is possible that the inverse relationship between hippocampal volume and PTSD symptom severity is already present soon after trauma. To test this possibility, we prospectively examined the association between hippocampal volumes and severity of PTSD symptoms within weeks to months after trauma due to a motor vehicle collision.

METHODS

Structural magnetic resonance imaging scans of 44 survivors were collected about 2 weeks and again at 3 months after a motor vehicle collision to measure hippocampal volumes. The PTSD Checklist was used to evaluate PTSD symptoms at each scan time. Full (n = 5) or partial (n = 6) PTSD was evaluated using the Clinician-Administered PTSD Scale at 3 months.

RESULTS

Left hippocampal volumes at both time points negatively correlated with PTSD Checklist scores, and with subscores for re-experiencing symptoms at 3 months. Left hippocampal volumes at 3 months also negatively correlated with hyperarousal symptoms at 3 months. Finally, neither left nor right hippocampal volumes significantly changed between 2 weeks and 3 months posttrauma.

CONCLUSIONS

The results suggest that small hippocampal volume at early posttrauma weeks is associated with increased risk for PTSD development. Furthermore, the inverse relationship between hippocampal volume and PTSD symptoms at 3 months did not arise from posttrauma shifts in hippocampal volume between 2 weeks and 3 months after trauma.

Context Processing and the Neurobiology of Post-Traumatic Stress Disorder

Progress in clinical and affective neuroscience is redefining psychiatric illness as symptomatic expression of cellular/molecular dysfunctions in specific brain circuits. Post-traumatic stress disorder (PTSD) has been an exemplar of this progress, with improved understanding of neurobiological systems subserving fear learning, salience detection, and emotion regulation explaining much of its phenomenology and neurobiology. However, many features remain unexplained and a parsimonious model that more fully accounts for symptoms and the core neurobiology remains elusive. Contextual processing is a key modulatory function of hippocampal-prefrontal-thalamic circuitry, allowing organisms to disambiguate cues and derive situation-specific meaning from the world. We propose that dysregulation within this context-processing circuit is at the core of PTSD pathophysiology, accounting for much of its phenomenology and most of its biological findings. Understanding core mechanisms like this, and their underlying neural circuits, will sharpen diagnostic precision and understanding of risk factors, enhancing our ability to develop preventive and "personalized" interventions.

Posttraumatic stress disorder symptom severity is associated with left hippocampal volume reduction: a meta-analytic study

OBJECTIVE

Many studies have reported hippocampal volume reductions associated with posttraumatic stress disorder (PTSD), while others have not. Here we provide an updated meta-analysis of such reductions associated with PTSD and evaluate the association between symptom severity and hippocampal volume.

METHODS

A total of 37 studies met the criteria for inclusion in the meta-analysis. Mean effect sizes (Hedges' g) and 95% confidence intervals (CI 95%) were computed for each study and then averaged to obtain an overall mean effect size across studies. Meta-regression was employed to examine the relationship between PTSD symptom severity and hippocampal volume.

RESULTS

Results showed that PTSD is associated with significant bilateral reduction of the hippocampus (left hippocampus effect size=-0.400, p<0.001, 5.24% reduction; right hippocampus effect size=-0.462, p<0.001, 5.23% reduction). Symptom severity, as measured by the Clinician-Administered PTSD Scale (CAPS), was significantly associated with decreased left, but not right, hippocampal volume.

CONCLUSIONS

PTSD was associated with significant bilateral volume reduction of the hippocampus. Increased symptom severity was significantly associated with reduced left hippocampal volume. This finding is consistent with the hypothesis that PTSD is more neurotoxic to the left hippocampus than to the right. However, whether the association between PTSD and lower hippocampal volume reflects a consequence of or a predisposition to PTSD remains unclear. More prospective studies are needed in this area.

Hippocampus Glutamate and N-Acetyl Aspartate Markers of Excitotoxic Neuronal Compromise in Posttraumatic Stress Disorder

Hippocampus atrophy is implicated in posttraumatic stress disorder (PTSD), and may partly reflect stress-induced glutamate excitotoxicity that culminates in neuron injury and manifests as re-experiencing symptoms and other memory abnormalities. This study used high-field proton magnetic resonance spectroscopy (MRS) to determine whether PTSD is associated with lower hippocampus levels of the neuron marker N-acetyl aspartate (NAA), along with higher levels of glutamate (Glu) and Glu/NAA. We also predicted that metabolite levels would correlate with re-experiencing symptoms and lifetime trauma load. Twenty-four adult PTSD patients and 23 trauma-exposed normal controls (TENC) underwent 4T MRS of the left and right hippocampus. Participants received psychiatric interviews, and completed the Traumatic Life Events Questionnaire to define lifetime trauma load. Relative to TENC participants, PTSD patients exhibited significantly lower NAA in right and left hippocampi, and significantly higher Glu and Glu/NAA in the right hippocampus. Re-experiencing symptoms were negatively correlated with left and right NAA, and positively correlated with right Glu and right Glu/NAA. Trauma load was positively correlated with right Glu/NAA in PTSD patients. When re-experiencing symptoms and trauma load were examined together in relation to right Glu/NAA, only re-experiencing symptoms remained a significant correlate. This represents the first report that PTSD is associated with MRS markers of hippocampus Glu excess, together with indices of compromised neuron integrity. Their robust associations with re-experiencing symptoms affirm that MRS indices of hippocampus neuron integrity and glutamate metabolism may reflect biomarkers of clinically significant disease variation in PTSD.

Salivary Cortisol and Regional Brain Volumes Among Veterans With and Without Posttraumatic Stress Disorder

BACKGROUND

Human studies have often found that brain regions rich in glucocorticoid receptors exhibit smaller volume in samples with past trauma and ongoing stress; however, relatively little research has addressed the hypothesis that such smaller volumes can be traced to elevated circulating glucocorticoid hormones (GCs). This issue takes on renewed interest in light of recent proposals to treat symptoms of stress disorders such as posttraumatic stress disorder (PTSD) with exogenous synthetic GCs. We sought to examine the relation of circulating GCs to brain macrostructure among veterans with and without PTSD.

METHODS

Participants (n = 90) included combat veterans with and without PTSD. Veterans completed self-report surveys, home-based cortisol samples, reactive cortisol samples over the course of two serial Trier Social Stress Tests, a low-dose dexamethasone suppression test, and structural magnetic resonance brain imaging over the course of 3 to 5 days.

RESULTS

No associations were observed between any salivary cortisol index and the volumes of the hippocampus or amygdala. A negative association was observed between evening basal cortisol and both FreeSurfer global volume and BrainImage supratentorial tissue volume. This effect was moderated by PTSD. Also observed was a positive association between reactive cortisol and these same brain volumes.

CONCLUSIONS

Estimates of cortical but not hippocampal or amygdala volume were moderately associated with evening basal salivary cortisol and cortisol reactivity to a social stressor. Existing models relating GC receptor density, circulating cortisol levels, and regional brain volumes received little support.

Posttraumatic stress disorder under ongoing threat: a review of neurobiological and neuroendocrine findings

BACKGROUND

Although numerous studies have investigated the neurobiology and neuroendocrinology of posttraumatic stress disorder (PTSD) after single finished trauma, studies on PTSD under ongoing threat are scarce and it is still unclear whether these individuals present similar abnormalities.

OBJECTIVE

The purpose of this review is to present the neurobiological and neuroendocrine findings on PTSD under ongoing threat. Ongoing threat considerably affects PTSD severity and treatment response and thus disentangling its neurobiological and neuroendocrine differences from PTSD after finished trauma could provide useful information for treatment.

METHOD

Eighteen studies that examined brain functioning and cortisol levels in relation to PTSD in individuals exposed to intimate partner violence, police officers, and fire fighters were included.

RESULTS

Hippocampal volume was decreased in PTSD under ongoing threat, although not consistently associated with symptom severity. The neuroimaging studies revealed that PTSD under ongoing threat was not characterized by reduced volume of amygdala or parahippocampal gyrus. The neurocircuitry model of PTSD after finished trauma with hyperactivation of amygdala and hypoactivation of prefrontal cortex and hippocampus was also confirmed in PTSD under ongoing threat. The neuroendocrine findings were inconsistent, revealing increased, decreased, or no association between cortisol levels and PTSD under ongoing threat.

CONCLUSIONS

Although PTSD under ongoing threat is characterized by abnormal neurocircuitry patterns similar to those previously found in PTSD after finished trauma, this is less so for other neurobiological and in particular neuroendocrine findings. Direct comparisons between samples with ongoing versus finished trauma are needed in future research to draw more solid conclusions before administering cortisol to patients with PTSD under ongoing threat who may already exhibit increased endogenous cortisol levels.

Burning odor-elicited anxiety in OEF/OIF combat veterans: Inverse relationship to gray matter volume in olfactory cortex

Despite the anatomical overlap between the brain's fear/threat and olfactory systems, a very limited number of investigations have considered the role of odors and the central olfactory system in the pathophysiology of PTSD. The goal of the present study was to assess structural differences in primary and secondary olfactory cortex between combat veterans with and without PTSD (CV + PTSD, CV-PTSD, respectively). An additional goal was to determine the relationship between gray matter volume (GMV) in olfactory cortex and the distressing properties of burning-related odors. A region of interest voxel-based morphometric (VBM) approach was used to measure GMV in olfactory cortex in a well-characterized group of CV + PTSD (n = 20) and CV-PTSD (n = 25). Prior to the MRI exam, combat-related (i.e., burning rubber) and control odors were systematically sampled and rated according to their potential for eliciting PTSD symptoms. Results showed that CV + PTSD exhibited significantly reduced GMV in anterior piriform (primary olfactory) and orbitofrontal (secondary olfactory) cortices compared to CV-PTSD (both p < .01). For the entire group, GMV in bilateral anterior piriform cortex was inversely related to burning rubber odor-elicited memories of trauma (p < .05). GMV in orbitofrontal cortex was inversely related to both clinical and laboratory measures of PTSD symptoms (all p < .05). In addition to replicating an established inverse relationship between GMV in anxiety-associated brain structures and PTSD symptomatology, the present study extends those findings by being the first report of volumetric decreases in olfactory cortex that are inversely related to odor-elicited PTSD symptoms. Potential mechanisms underlying these findings are discussed.

Chronic stress and brain plasticity: Mechanisms underlying adaptive and maladaptive changes and implications for stress-related CNS disorders

Stress responses entail neuroendocrine, autonomic, and behavioral changes to promote effective coping with real or perceived threats to one's safety. While these responses are critical for the survival of the individual, adverse effects of repeated exposure to stress are widely known to have deleterious effects on health. Thus, a considerable effort in the search for treatments to stress-related CNS disorders necessitates unraveling the brain mechanisms responsible for adaptation under acute conditions and their perturbations following chronic stress exposure. This paper is based upon a symposium from the 2014 International Behavioral Neuroscience Meeting, summarizing some recent advances in understanding the effects of stress on adaptive and maladaptive responses subserved by limbic forebrain networks. An important theme highlighted in this review is that the same networks mediating neuroendocrine, autonomic, and behavioral processes during adaptive coping also comprise targets of the effects of repeated stress exposure in the development of maladaptive states. Where possible, reference is made to the similarity of neurobiological substrates and effects observed following repeated exposure to stress in laboratory animals and the clinical features of stress-related disorders in humans.

Is Online Learning a Viable Training Option for Teaching Sexual Assault Forensic Examiners?

This study assessed knowledge attainment of healthcare professionals who participated in a nationwide sexual assault forensic examiner training program developed by the International Association of Forensic Nursing. A comprehensive curriculum was divided into 12 modules that students accessed through an online learning management system. Using a one-group pretest-posttest design, we assessed students' knowledge attainment for all 12 online modules. The results showed that the mean posttest scores were significantly greater than the mean pretest scores for all 12 online modules. On over 40% of the modules, the students exhibited at least a 25% knowledge gain. This study also examined the predictors of knowledge attainment. Using a multiple linear regression model, we found that knowledge attainment was positively associated with a reliable Internet connection, students who were drawn to the training because it was of no cost to them, and those students with higher levels of motivation. By contrast, lower knowledge gains were significantly related to students who reported more work/personal barriers and those who were drawn to sexual assault forensic examiner practice because they, or someone close to them, have personal experience with sexual assault.

Hatha Yoga and Executive Function: A Systematic Review

INTRODUCTION

Recent reviews have documented the beneficial effects of seated meditation on executive function (EF). However, there has yet to be a comprehensive review on the effects of Hatha yoga, a moving meditation, on EF.

OBJECTIVE

To examine the empirical literature on the effects of Hatha yoga on EF.

METHODS

MEDLINE, Scopus, and PsycINFO databases were searched for experimental studies (between- or within-subject designs) testing the effects of Hatha yoga (acute bouts, short-term interventions, longer-term interventions) on EF.

RESULTS

A total of 11 published studies met eligibility criteria: Three studies involved healthy adults, 2 studies involved healthy older adults (n = 2), 1 study involved children and adolescents, and 5 studies involved medical (n = 4) or forensic (n = 1) populations. In healthy adults, 2 of 3 studies suggested that acute bouts of Hatha yoga improved EF; however, 1 study using a short-term intervention found no improvements in EF. Among healthy older adults, 1 study provided evidence that Hatha yoga improves EF. In child/adolescent samples, 1 study supported the contention that Hatha yoga improves EF after short-term interventions. Among medical populations, EF improved in patients with type 2 diabetes mellitus and in 1 of 3 studies involving patients with multiple sclerosis. The sole study involving impulsive prisoners showed positive effects on EF with a short-term intervention.

CONCLUSION

Hatha yoga shows promise of benefit for EF in healthy adults, children, adolescents, healthy older adults, impulsive prisoners, and medical populations (with the exception of multiple sclerosis). However, more good-quality studies that evaluate the efficacy of Hatha yoga's effects on EF are essential to build on this evidence base.

Differential effects of stress-induced cortisol responses on recollection and familiarity-based recognition memory

Stress-induced changes in cortisol can impact memory in various ways. However, the precise relationship between cortisol and recognition memory is still poorly understood. For instance, there is reason to believe that stress could differentially affect recollection-based memory, which depends on the hippocampus, and familiarity-based recognition, which can be supported by neocortical areas alone. Accordingly, in the current study we examined the effects of stress-related changes in cortisol on the processes underlying recognition memory. Stress was induced with a cold-pressor test after incidental encoding of emotional and neutral pictures, and recollection and familiarity-based recognition memory were measured one day later. The relationship between stress-induced cortisol responses and recollection was non-monotonic, such that subjects with moderate stress-related increases in cortisol had the highest levels of recollection. In contrast, stress-related cortisol responses were linearly related to increases in familiarity. In addition, measures of cortisol taken at the onset of the experiment showed that individuals with higher levels of pre-learning cortisol had lower levels of both recollection and familiarity. The results are consistent with the proposition that hippocampal-dependent memory processes such as recollection function optimally under moderate levels of stress, whereas more cortically-based processes such as familiarity are enhanced even with higher levels of stress. These results indicate that whether post-encoding stress improves or disrupts recognition memory depends on the specific memory process examined as well as the magnitude of the stress-induced cortisol response.

Theta, mental flexibility, and post-traumatic stress disorder: connecting in the parietal cortex

Post-traumatic stress disorder (PTSD) is a mental health injury characterised by re-experiencing, avoidance, numbing and hyperarousal. Whilst the aetiology of the disorder is relatively well understood, there is debate about the prevalence of cognitive sequelae that manifest in PTSD. In particular, there are conflicting reports about deficits in executive function and mental flexibility. Even less is known about the neural changes that underlie such deficits. Here, we used magnetoencephalography to study differences in functional connectivity during a mental flexibility task in combat-related PTSD (all males, mean age = 37.4, n = 18) versus a military control (all males, mean age = 33.05, n = 19) group. We observed large-scale increases in theta connectivity in the PTSD group compared to controls. The PTSD group performance was compromised in the more attentionally-demanding task and this was characterised by 'late-stage' theta hyperconnectivity, concentrated in network connections involving right parietal cortex. Furthermore, we observed significant correlations with the connectivity strength in this region with a number of cognitive-behavioural outcomes, including measures of attention, depression and anxiety. These findings suggest atypical coordination of neural synchronisation in large scale networks contributes to deficits in mental flexibility for PTSD populations in timed, attentionally-demanding tasks, and this propensity toward network hyperconnectivity may play a more general role in the cognitive sequelae evident in this disorder.

A quantitative meta-analysis of neurocognitive functioning in posttraumatic stress disorder

Posttraumatic stress disorder (PTSD) is associated with regional alterations in brain structure and function that are hypothesized to contribute to symptoms and cognitive deficits associated with the disorder. We present here the first systematic meta-analysis of neurocognitive outcomes associated with PTSD to examine a broad range of cognitive domains and describe the profile of cognitive deficits, as well as modifying clinical factors and study characteristics. This report is based on data from 60 studies totaling 4,108 participants, including 1,779 with PTSD, 1,446 trauma-exposed comparison participants, and 895 healthy comparison participants without trauma exposure. Effect-size estimates were calculated using a mixed-effects meta-analysis for 9 cognitive domains: attention/working memory, executive functions, verbal learning, verbal memory, visual learning, visual memory, language, speed of information processing, and visuospatial abilities. Analyses revealed significant neurocognitive effects associated with PTSD, although these ranged widely in magnitude, with the largest effect sizes in verbal learning (d = -.62), speed of information processing (d = -.59), attention/working memory (d = -.50), and verbal memory (d =-.46). Effect-size estimates were significantly larger in treatment-seeking than community samples and in studies that did not exclude participants with attention-deficit/hyperactivity disorder, and effect sizes were affected by between-group IQ discrepancies and the gender composition of the PTSD groups. Our findings indicate that consideration of neuropsychological functioning in attention, verbal memory, and speed of information processing may have important implications for the effective clinical management of persons with PTSD. Results are further discussed in the context of cognitive models of PTSD and the limitations of this literature.