Adapting to Stress: Understanding the Neurobiology of Resilience

Venlafaxine Improves the Cognitive Impairment and Depression-Like Behaviors in a Cuprizone Mouse Model by Alleviating Demyelination and Neuroinflammation in the Brain

Growing evidence has implicated that myelin deficits and neuroinflammation are the coexisted pathological features that contribute to the mood swing and cognitive decline in major depressive disorder (MDD) and multiple sclerosis (MS). Therefore, attenuation of neuroinflammation and reduction of demyelination became newly emerging treatment strategies for the mood and cognitive symptoms. Antidepressant venlafaxine has been used in depression and anxiety through its multiple neuroprotective effects. However, it is unclear whether venlafaxine can improve myelin integrity and alter inflammation status in the brain. By using a well-established cuprizone-induced acute mouse model of demyelination, we investigated the protective effects of venlafaxine on these facets. The cuprizone-fed animals exhibited cognitive impairment and mood disturbances together with myelin loss and prominent neuroinflammation in the brain. Our present study showed that a high dose of venlafaxine alleviated the loss of myelin and oligodendrocytes (OLs), mitigated depression-like behaviors, and improved cognitive function in cuprizone-fed animals. Data from the present study also showed that venlafaxine reduced microglia-mediated inflammation in the brains of cuprizone-fed animals. These findings suggest that venlafaxine may exert its therapeutic effects via facilitating myelin integrity and controlling neuroinflammation, which may provide extra benefits to MS patients with depression and anxiety beyond the symptom management.

Exploring the mutual regulation between oxytocin and cortisol as a marker of resilience

Early trauma can increase the risk for developing posttraumatic stress disorder (PTSD) in adulthood. Early trauma has also been associated with the dysregulation between the hypothalamic-pituitary-adrenal (HPA) and oxytocin systems and may influence the co-regulation between these two systems. But whether the mutual regulation of the two systems represents a sign of resilience and/or mutual dysregulation could be a sign of vulnerability to PTSD and the dissociative subtype of PTSD (PTSD-D) is unknown. The study aims to synthesize and conduct a preliminary test of a conceptual model of the mutual regulation between these two systems as a marker of resilience. We analyzed a pilot data with 22 pregnant women in 3 groups (PTSD only, PTSD-D, and trauma-exposed resilient controls) and repeated measures of plasma oxytocin and cortisol. Oxytocin and cortisol seemed reciprocal in all three groups, but both levels were relatively high in women with PTSD-D and low in those with PTSD compared with controls. This suggests that both hormones in women with PTSD-D and PTSD only are dysregulated, but not lacking in reciprocity.

Biopsychosocial approach to understanding resilience: Stress habituation and where to intervene

BACKGROUND

Resilience in the face of adversity is a human experience that leads to better health, both mentally and physically. We briefly review its historical origins rooted in ecological biology and its adoption into health care. Resilience is the common response to adversity or potential traumatic events. Individual differences in emotion regulation and coping skills as well as social capital and one's physical environment influence a person's ability to achieve resilience.

PROPOSED MECHANISM

One potential biopsychosocial measure of resilience includes stress habituation to repeated stress as demonstrated in the laboratory, possibly providing a tool to observe mastery of resilience training in the clinic. Evidence-based interventions at the individual and small group level (eg, family, classroom) have successfully shown development of resilient behaviours and improved mental and physical health outcomes. However, the role of social context and public policy clearly influence an individual's ability to be resilient.

CONCLUSIONS

Despite the current limited evidence of the effectiveness of resilience building interventions, clinicians, researchers, and other health care professions have an obligation to become advocates for laws and policies that support the most vulnerable, and least resilient, in our society to attain resilience for their health. This salutary effect will enable them to become socially as well as economically productive members of the community at large. It is not possible to remove stress or adversity from life, but we can influence the development of regulatory flexibility and decrease the sociocultural factors linked to the nonresilient experience, thus mitigating adversity's long-term effects on health.

Patterns of adversity and pathways to health among White, Black, and Latinx youth

Research has demonstrated the negative impact of Adverse Childhood Experiences (ACEs) on long-term trajectories of mental and physical health. Yet existing literature on this topic is limited in its understanding of outcomes among youth samples, optimal measurement items and methods, and differences in adverse experiences across race/ethnicity. The current study used a person-centered approach to measure ACEs and their impact on youth health outcomes across three different racial/ethnic groups from a large national database. Patterns of exposure to adverse experiences among Black, Latinx, and White youth (N = 30,668, ages 12-17) were determined empirically using latent class analysis (LCA). Significant differences in class membership by demographic indicators (age, household income, sex) and concurrent health outcomes were identified. Different models emerged for Black (2 classes), Latinx (3 classes), and White youth (3 classes). Older and lower-income youth were more likely to have experienced adversities, but there were no differences in adversity likelihood by sex. Additionally, racial/ethnic minority youth were at greater risk of experiencing higher levels of adversity, poverty, and poor health when compared to their White counterparts. Rather than occuring in meaningful clusters, adverse experiences among youth reflected a cumulative risk model such that classes were defined by the overall intensity of adverse experiences (i.e., low, moderate, high). Findings provide greater knowledge regarding the relationship between ACEs and health and future research directions to inform more targeted and culturally-appropriate screening, prevention, and intervention programs.

Is psychological stress a predisposing factor for amyotrophic lateral sclerosis (ALS)? An online international case-control study of premorbid life events, occupational stress, resilience and anxiety

Psychological stress has been suggested to be relevant to the pathogenesis of neurodegenerative disorders, possibly via the generation of oxygen free radicals. We therefore sought to determine whether people with amyotrophic lateral sclerosis (ALS) had been subjected to more potentially stressful life events or occupations than controls, and whether they had differences in resilience or trait anxiety that would moderate their responses to these stressors. An online anonymous multilingual questionnaire was used to collect data on significant life events from people with and without ALS, using items from a modified Social Readjustment Rating Scale and from self-described significant events, which were combined to create a Life Events Inventory. Inventory scores were subdivided into 0–20 years and 21–40 years age ranges, and for the preceding 2, 5 and 10 years. Respondents also rated levels of stress experienced during different occupations. Resilience was measured using the Connor-Davidson Resilience Scale, and trait anxiety with a modified Geriatric Anxiety Inventory. Scores were compared using nonparametric statistics. Data from 400 ALS (251 male, 149 female) and 450 control (130 male, 320 female) respondents aged 40 years and over showed that Life Events Inventory scores were similar in male ALS respondents and controls, but lower in female ALS respondents than female controls for the preceding 5-year and 10-year periods. Occupational stress did not differ between ALS respondents and controls. Both male and female ALS respondents had higher resilience scores than controls. Anxiety scores did not differ between ALS and control groups. In conclusion, people with ALS reported no raised levels of potentially stressful premorbid life events or occupational stress, and did not have reduced levels of resilience, or increased levels of anxiety, that would augment the deleterious effects of stressors. On the contrary, ALS respondents had higher resilience than controls, though this conclusion relies on ALS respondents recalling their premorbid status. These results do not support the hypothesis that psychological stress from significant life events or occupational stress plays a role in the pathogenesis of ALS.

A Systematic Review of Genetic Influence on Psychological Resilience

When exposed to adversity, some individuals are at an increased risk of posttraumatic stress disorder, experiencing persistent biopsychosocial disturbances, whereas others adapt well, described as resilience. Resilience is a complex biopsychosocial phenomenon conceptualized as adaptation to adversity influenced by an individual’s genetic variants, epistasis, epigenetics, and gene-by-environment interactions. Studies on psychological resilience have focused on behavioral and psychosocial variables with far less examination of the genetic contributions. The purpose of this review is to identify specific genetic variants contributing to the biological capacity for psychological resilience. PubMed and PsycINFO were searched using the following key words: psychological resilience AND genotype(s). Additional articles were identified from the Human Genome Epidemiology Navigator using the term resilience, psychological. Ten studies met the criteria. Six genes were empirically associated with psychological resilience: serotonin-transporter-linked polymorphic region ( 5-HTTLPR), dopamine receptor D4, brain-derived neurotrophic factor ( BDNF), corticotropin-releasing hormone receptor 1, oxytocin receptor and regulator of G-protein signaling 2 . The findings of this systematic review suggest that the L/L or L’/L’ genotype of 5-HTTLPR and rs25531 in children/adolescents and the S/S or S’/S’ genotype in adults are most frequently related to resilience. Additionally, the Val/Val genotype of rs6265 in BDNF in Caucasians was also associated with resilience. There are numerous factors contributing to the complexity of determining the genetic influence on resilience including analysis of rs25531, assumptions of the mode of inheritance, operationalization of resilience, demographic and population characteristics, sample size, and other types of genetic influence including epistasis and epigenetics. While current evidence is supportive, further investigation of the genetic influence on resilience is required.

Cyr N, Narr KL, Lavretsky H. Resilience and White Matter Integrity in Geriatric Depression

OBJECTIVE

Greater psychological resilience may protect against developing depression in a growing geriatric population. Identifying the neural correlates of resilience in geriatric depression could provide neurobiologic targets to inform clinical interventions. However, most prior neuroimaging studies have only considered the presence or absence of resilience and have not addressed the multifactorial nature of resilience. The current study aimed to establish the neural correlates of four factors of resilience in the depressed elderly.

METHODS

White matter integrity was assessed using diffusion-weighted magnetic resonance imaging data collected from 70 older adults with major depressive disorder. We used four resilience factors previously derived in an exploratory factor analysis of the Connor-Davidson Resilience Scale in a large sample of depressed older adults: 1, grit; 2, active coping self-efficacy; 3, accommodative coping self-efficacy; and 4, spirituality.

RESULTS

The resilience factor "grit" was positively associated with fractional anisotropy in the callosal region connecting prefrontal cortex and fractional anisotropy in cingulum fibers; however, the latter did not survive correction for multiple comparisons.

CONCLUSION

Structural integrity of major white matter pathways implicated in cognitive control and emotion regulation (i.e., connecting prefrontal cortex) was positively associated with the resilience factor "grit" in our sample of older adults with depression. Prospective studies are needed to determine the utility of the structural integrity of these pathways as a biomarker in predicting risk for depression and treatment response.

Psychological Consequences of Human Trafficking: Complex Posttraumatic Stress Disorder in Trafficked Children

Trafficked children are frequently exposed to multiple traumatic events, including during their recruitment, transit, and exploitation. It has been hypothesized that such exposures can lead to the development of Complex Posttraumatic Stress Disorder (PTSD). Complex PTSD includes (in addition to the core PTSD symptoms of re-experiencing, avoidance, and hyperarousal) disturbances in affect regulation, dissociation, self-concept, interpersonal relationships, somatization, and systems of meaning. This historical cohort study aimed to investigate Complex PTSD in trafficked children with a diagnosis of PTSD and compare these with nontrafficked controls exposed to single or multiple trauma. Trafficked children were identified by keyword searches of the electronic health records of more than 250,000 mental health service users; a matched cohort of nontrafficked children was randomly selected. Regression models compared the number of Complex PTSD symptoms in trafficked children and non-trafficked children who had experienced multiple or single trauma. Fifty-one trafficked children were identified: eleven with a diagnosis of PTSD (22%). A high proportion of trafficked children with PTSD had Complex PTSD symptoms. Trafficked and non-trafficked children with PTSD who had been exposed to multiple trauma showed a greater number of Complex PTSD symptoms compared to nontrafficked children with PTSD exposed to single-event traumas. Somatic symptoms were noted for almost two-thirds of the trafficked children but only 10%-11% of the nontrafficked children. Child trafficking and multiple trauma exposure are associated with more complex posttraumatic presentations. A thorough clinical assessment at intake is crucial to ensure additional symptoms can be meaningfully incorporated into treatment plans.

Toxicity, recovery, and resilience in a 3D dopaminergic neuronal in vitro model exposed to rotenone

To date, most in vitro toxicity testing has focused on acute effects of compounds at high concentrations. This testing strategy does not reflect real-life exposures, which might contribute to long-term disease outcome. We used a 3D-human dopaminergic in vitro LUHMES cell line model to determine whether effects of short-term rotenone exposure (100 nM, 24 h) are permanent or reversible. A decrease in complex I activity, ATP, mitochondrial diameter, and neurite outgrowth were observed acutely. After compound removal, complex I activity was still inhibited; however, ATP levels were increased, cells were electrically active and aggregates restored neurite outgrowth integrity and mitochondrial morphology. We identified significant transcriptomic changes after 24 h which were not present 7 days after wash-out. Our results suggest that testing short-term exposures in vitro may capture many acute effects which cells can overcome, missing adaptive processes, and long-term mechanisms. In addition, to study cellular resilience, cells were re-exposed to rotenone after wash-out and recovery period. Pre-exposed cells maintained higher metabolic activity than controls and presented a different expression pattern in genes previously shown to be altered by rotenone. NEF2L2, ATF4, and EAAC1 were downregulated upon single hit on day 14, but unchanged in pre-exposed aggregates. DAT and CASP3 were only altered after re-exposure to rotenone, while TYMS and MLF1IP were downregulated in both single-exposed and pre-exposed aggregates. In summary, our study shows that a human cell-based 3D model can be used to assess cellular adaptation, resilience, and long-term mechanisms relevant to neurodegenerative research.

Autonomic and Brain Morphological Predictors of Stress Resilience

Stressful life events are an important cause of psychopathology. Humans exposed to aversive or stressful experiences show considerable inter-individual heterogeneity in their responses. However, the majority does not develop stress-related psychiatric disorders. The dynamic processes encompassing positive and functional adaptation in the face of significant adversity have been broadly defined as resilience. Traditionally, the assessment of resilience has been confined to self-report measures, both within the general community and putative high-risk populations. Although this approach has value, it is highly susceptible to subjective bias and may not capture the dynamic nature of resilience, as underlying construct. Recognizing the obvious benefits of more objective measures of resilience, research in the field has just started investigating the predictive value of several potential biological markers. This review provides an overview of theoretical views and empirical evidence suggesting that individual differences in heart rate variability (HRV), a surrogate index of resting cardiac vagal outflow, may underlie different levels of resilience toward the development of stress-related psychiatric disorders. Following this line of thought, recent studies describing associations between regional brain morphometric characteristics and resting state vagally-mediated HRV are summarized. Existing studies suggest that the structural morphology of the anterior cingulated cortex (ACC), particularly its cortical thickness, is implicated in the expression of individual differences in HRV. These findings are discussed in light of emerging structural neuroimaging research, linking morphological characteristics of the ACC to psychological traits ascribed to a high-resilient profile and abnormal structural integrity of the ACC to the psychophysiological expression of stress-related mental health consequences. We conclude that a multidisciplinary approach integrating brain structural imaging with HRV monitoring could offer novel perspectives about brain-body pathways in resilience and adaptation to psychological stress.

Morphological brain measures of cortico-limbic inhibition related to resilience

Resilience is the ability to adequately adapt and respond to homeostatic perturbations. Although resilience has been associated with positive health outcomes, the neuro-biological basis of resilience is poorly understood. The aim of the study was to identify associations between regional brain morphology and trait resilience with a focus on resilience-related morphological differences in brain regions involved in cortico-limbic inhibition. The relationship between resilience and measures of affect were also investigated. Forty-eight healthy subjects completed structural MRI scans. Self-reported resilience was measured using the Connor and Davidson Resilience Scale. Segmentation and regional parcellation of images was performed to yield a total of 165 regions. Gray matter volume (GMV), cortical thickness, surface area, and mean curvature were calculated for each region. Regression models were used to identify associations between morphology of regions belonging to executive control and emotional arousal brain networks and trait resilience (total and subscales) while controlling for age, sex, and total GMV. Correlations were also conducted between resilience scores and affect scores. Significant associations were found between GM changes in hypothesized brain regions (subparietal sulcus, intraparietal sulcus, amygdala, anterior mid cingulate cortex, and subgenual cingulate cortex) and resilience scores. There were significant positive correlations between resilience and positive affect and negative correlations with negative affect. Resilience was associated with brain morphology of regions involved in cognitive and affective processes related to cortico-limbic inhibition. Brain signatures associated with resilience may be a biomarker of vulnerability to disease. © 2016 Wiley Periodicals, Inc.