Abstract This paper integrates the cumulative stress hypothesis with the mismatch hypothesis, taking into account individual differences in sensitivity to programming. According to the cumulative ...stress hypothesis, individuals are more likely to suffer from disease as adversity accumulates. According to the mismatch hypothesis, individuals are more likely to suffer from disease if a mismatch occurs between the early programming environment and the later adult environment. These seemingly contradicting hypotheses are integrated into a new model proposing that the cumulative stress hypothesis applies to individuals who were not or only to a small extent programmed by their early environment, while the mismatch hypothesis applies to individuals who experienced strong programming effects. Evidence for the main effects of adversity as well as evidence for the interaction between adversity in early and later life is presented from human observational studies and animal models. Next, convincing evidence for individual differences in sensitivity to programming is presented. We extensively discuss how our integrated model can be tested empirically in animal models and human studies, inviting researchers to test this model. Furthermore, this integrated model should tempt clinicians and other intervenors to interpret symptoms as possible adaptations from an evolutionary biology perspective.
Recent years have seen increased interest in psychopathologies related to trauma exposure. Specifically, there has been a growing awareness to posttraumatic stress disorder (PTSD) in part due to ...terrorism, climate change-associated natural disasters, the global refugee crisis, and increased violence in overpopulated urban areas. However, notwithstanding the increased awareness to the disorder, the increasing number of patients, and the devastating impact on the lives of patients and their families, the efficacy of available treatments remains limited and highly unsatisfactory. A major scientific effort is therefore devoted to unravel the neural mechanisms underlying PTSD with the aim of paving the way to developing novel or improved treatment approaches and drugs to treat PTSD. One of the major scientific tools used to gain insight into understanding physiological and neuronal mechanisms underlying diseases and for treatment development is the use of animal models of human diseases. While much progress has been made using these models in understanding mechanisms of conditioned fear and fear memory, the gained knowledge has not yet led to better treatment options for PTSD patients. This poor translational outcome has already led some scientists and pharmaceutical companies, who do not in general hold opinions against animal models, to propose that those models should be abandoned. Here, we critically examine aspects of animal models of PTSD that may have contributed to the relative lack of translatability, including the focus on the exposure to trauma, overlooking individual and sex differences, and the contribution of risk factors. Based on findings from recent years, we propose research-based modifications that we believe are required in order to overcome some of the shortcomings of previous practice. These modifications include the usage of animal models of PTSD which incorporate risk factors and of the behavioral profiling analysis of individuals in a sample. These modifications are aimed to address factors such as individual predisposition and resilience, thus taking into consideration the fact that only a fraction of individuals exposed to trauma develop PTSD. We suggest that with an appropriate shift of practice, animal models are not only a valuable tool to enhance our understanding of fear and memory processes, but could serve as effective platforms for understanding PTSD, for PTSD drug development and drug testing.
Summary Early life stress is one of the best characterized risk factors for psychiatric disorders, including depression, and many animal models have therefore studied the long-term physiological and ...behavioural consequences of early life stress. In most approaches a very deterministic view of adverse experiences early in life prevails, linking these events inevitably with later pathology. By summarizing literature on early life programming and adaptive phenotypic plasticity the current review proposes that early life challenges may induce changes that prepare an individual for life in a more hostile environment and are therefore predominantly beneficial. Adult diseases as depression might thus not be promoted by early life adversity per se, but by a mismatch of the programmed and the later actual environment in combination with a more vulnerable or resilient genetic predisposition. The present review further discusses the ability of currently available animal models for depression to investigate this novel hypothesis. Finally, a number of criteria and research strategies are outlined that would be necessary to address the mismatch hypothesis of depression.
N6-methyladenosine (m6A) and N6,2′-O-dimethyladenosine (m6Am) are abundant mRNA modifications that regulate transcript processing and translation. The role of both, here termed m6A/m, in the stress ...response in the adult brain in vivo is currently unknown. Here, we provide a detailed analysis of the stress epitranscriptome using m6A/m-seq, global and gene-specific m6A/m measurements. We show that stress exposure and glucocorticoids region and time specifically alter m6A/m and its regulatory network. We demonstrate that deletion of the methyltransferase Mettl3 or the demethylase Fto in adult neurons alters the m6A/m epitranscriptome, increases fear memory, and changes the transcriptome response to fear and synaptic plasticity. Moreover, we report that regulation of m6A/m is impaired in major depressive disorder patients following glucocorticoid stimulation. Our findings indicate that brain m6A/m represents a novel layer of complexity in gene expression regulation after stress and that dysregulation of the m6A/m response may contribute to the pathophysiology of stress-related psychiatric disorders.
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•m6A/m mRNA methylation in the adult mouse brain is regulated by stress•m6A/m mRNA regulation is brain region, time, and gene specific•Mettl3 and Fto cKO alter m6A/m, fear memory, expression, and synaptic plasticity•The m6A/m glucocorticoid response is impaired in major depressive disorder patients
Engel et al. demonstrate a region- and time-dependent role of brain m6A/m methylation in stress-response regulation. Manipulating m6A/m alters fear memory, transcriptome response, and synaptic plasticity. Altered m6A/m dynamics in depressed patients suggest importance of m6A/m modifications for stress-related psychiatric disorders.
The epidemic of the 2019 novel coronavirus SARS-CoV-2, causing the coronavirus disease 2019 (COVID-19) is a global public health emergency with multifaceted severe consequences for people's lives and ...their mental health. In this article, as members of the European College of Neuropsychopharmacology (ECNP) Resilience, we will discuss the urgent need for a focus on resilience during the current coronavirus pandemic. Resilience is pivotal to cope with stress and vital to stay in balance. We will discuss the importance of resilience at the individual and societal level, but also the implication for patients with a psychiatric condition and health care workers. We not only advocate for an increased focus on mental health during the coronavirus pandemic but also highlight the urgent need of augmenting our focus on resilience and on strategies to enhance it.
Chronic stress has been found to be a major risk factor for various human pathologies. Stress activates the hypothalamic-pituitary-adrenal (HPA) axis, which is tightly regulated via, among others, ...the glucocorticoid receptor (GR). The activity of the GR is modulated by a variety of proteins, including the co-chaperone FK506 binding protein 51 (FKBP5). Although FKBP5 has been associated with risk for affective disorders and has been implicated in GR sensitivity, previous studies focused mainly on peripheral blood, while information about basal distribution and induction in the central nervous system are sparse.
In the present study, we describe the basal expression pattern of Fkbp5 mRNA in the brain of adult male mice and show the induction of Fkbp5 mRNA via dexamethasone treatment or different stress paradigms. We could show that Fkbp5 is often, but not exclusively, expressed in regions also known for GR expression, for example the hippocampus. Furthermore, we were able to induce Fkbp5 expression via dexamethasone in the CA1 and DG subregions of the hippocampus, the paraventricular nucleus (PVN) and the central amygdala (CeA). Increase of Fkbp5 mRNA was also found after restrained stress and 24 hours of food deprivation in the PVN and the CeA, while in the hippocampus only food deprivation caused an increase in Fkbp5 mRNA.
Interestingly, regions with a low basal expression showed higher increase in Fkbp5 mRNA following induction than regions with high basal expression, supporting the hypothesis that GR sensitivity is, at least partly, mediated via Fkbp5. In addition, this also supports the use of Fkbp5 gene expression as a marker for GR sensitivity. In summary, we were able to give an overview of the basal expression of fkbp5 mRNA as well as to extend the findings of induction of Fkbp5 and its regulatory influence on GR sensitivity from peripheral blood to the brain.
Sex differences and social context independently contribute to the development of stress-related disorders. However, less is known about how their interplay might influence behavior and physiology. ...Here we focused on social hierarchy status, a major component of the social environment in mice, and whether it influences behavioral adaptation to chronic stress in a sex-specific manner. We used a high-throughput automated behavioral monitoring system to assess social dominance in same-sex, group-living mice. We found that position in the social hierarchy at baseline was a significant predictor of multiple behavioral outcomes following exposure to chronic stress. Crucially, this association carried opposite consequences for the two sexes. This work demonstrates the importance of recognizing the interplay between sex and social factors and enhances our understating of how individual differences shape the stress response.
The global public health crisis caused by COVID-19 has lasted longer than many of us would have hoped and expected. With its high uncertainty and limited control, the COVID-19 pandemic has ...undoubtedly asked a lot from all of us. One important central question is: how resilient have we proved in face of the unprecedented and prolonged coronavirus pandemic? There is a vast and rapidly growing literature that has examined the impact of the pandemic on mental health both on the shorter (2020) and longer (2021) term. This not only concerns pandemic-related effects on resilience in the general population, but also how the pandemic has challenged stress resilience and mental health outcomes across more specific vulnerable population groups: patients with a psychiatric disorder, COVID-19 diagnosed patients, health care workers, children and adolescents, pregnant women, and elderly people. It is challenging to keep up to date with, and interpret, this rapidly increasing scientific literature. In this review, we provide a critical overview on how the COVID-19 pandemic has impacted mental health and how human stress resilience has been shaped by the pandemic on the shorter and longer term. The vast literature is dominated by a wealth of data which are, however, not always of the highest quality and heavily depend on online and self-report surveys. Nevertheless, it appears that we have proven surprisingly resilient over time, with fast recovery from COVID-19 measures. Still, vulnerable groups such as adolescents and health care personnel that have been severely impacted by the COVID-19 pandemic do exist. Large interindividual differences exist, and for future pandemics there is a clear need to comprehensively and integratively assess resilience from the start to provide personalized help and interventions tailored to the specific needs for vulnerable groups.
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