Correlation between the level of microRNA expression in peripheral blood mononuclear cells and symptomatology in patients with generalized anxiety disorder

Assessing the feasibility of using salivary microRNAs as biomarkers to distinguish between chronic stress and childhood trauma in African American young women in an exploratory pilot study

Introduction

The current study assessed the impact of self-reported stress measures on microRNA (miRNA) profiles in saliva exosomes. Saliva is one of the most accessible and non-invasive bodily fluids and exosomal miRNAs in saliva could be useful in (1) measuring stress states and (2) distinguishing between individuals suffering from high levels of chronic stress vs. adverse childhood experiences (ACEs). miRNAs are small, noncoding RNAs that act as gene regulators. Several studies have shown differential expressions of certain miRNA in neurological diseases and in stress, post-traumatic stress syndrome (PTSD) and anxiety. Detailed analyses of miRNA expressions and profiling of miRNAs among populations with various exposures to traumatic and life stressors have not been carried out. The goal of our study was to discover miRNAs associated with high chronic stress or childhood trauma.

Method

This study sought to explore miRNA expression in African American young women from a small, southern Historically Black College and University (HBCU). Twelve participants completed the social readjustment rating scale (SRRS), ACEs scale, and saliva collection and were divided into three groups based on ACE and chronic stress score: Low Chronic Stress (LCS; n = 4); High Chronic Stress (HCS; n = 4); High Chronic Stress + High ACEs (HCS+HA; n=4). A custom-made miRNA Taqman-Array tested for fold change in four miRNAs (i.e., miR-19b, miR-187, miR-34a and miR-135-3p).

Results

There was a significant downregulation of miR-19b (χ 2(2, N=12) = 7.42, p < 0.01, η²= 0.915), miR-187 (χ 2 (2, N = 12) = 7.36, p < 0.05, η²= 0.598), and miR-34a (χ 2(2, N = 12) = 7.42, p < 0.05, η²= 0.60). in both the HCS and the HCS+HA groups vs. LCS. Interestingly, miR-135-3p (χ 2(2, N = 12) = 8.00, p < 0.05, η²= 0.67. was upregulated in the HCS group vs. LCS and HCS+LA. Expression for miR-135-3p was not significantly different between LCS + HCS+HA.

Conclusion

Our analyses shows that miRNA extracted from salivary exosomes can be a reliable biomarker for stress and miR-135a-3p appears to be the most upregulated between LCS and HCS individuals and a potential candidate to corroborate self-reports on self-assessments and predict negative health outcomes. Given that HCS+HA did not show an upregulation of miR-135-3p but had similar expression in the other three miRs compared to HCS group may indicate an adaptive stress response following early life adversity. Further, downregulation in miR-135-3p in individuals with high levels of chronic stress could point to unknown childhood trauma exposure (e.g. closed adoptions, dissociative amnesia, abuse). A major limitation in this study is the small sample size and future directions include determining the predictive validity of these miRNAs in predicting onset of physical and mental health outcomes for early interventions in larger studies.

Regulation of miRNA expression in the prefrontal cortex by fecal microbiota transplantation in anxiety-like mice

Background

The gut-brain axis and gut microbiota have emerged as key players in emotional disorders. Recent studies suggest that alterations in gut microbiota may impact psychiatric symptoms through brain miRNA along the gut-brain axis. However, direct evidence linking gut microbiota to the pathophysiology of generalized anxiety disorder (GAD) via brain miRNA is limited. In this study, we explored the effects of fecal microbiota transplantation (FMT) from GAD donors on gut microbiota and prefrontal cortex miRNA in recipient mice, aiming to understand the relationship between these two factors.

Methods

Anxiety scores and gut microbiota composition were assessed in GAD patients, and their fecal samples were utilized for FMT in C57BL/6J mice. Anxiety-like behavior in mice was evaluated using open field and elevated plus maze tests. High-throughput sequencing of gut microbiota 16S rRNA and prefrontal cortex miRNA was performed.

Results

The fecal microbiota of GAD patients exhibited a distinct microbial structure compared to the healthy group, characterized by a significant decrease in Verrucomicrobia and Akkermansia, and a significant increase in Actinobacteria and Bacteroides. Subsequent FMT from GAD patients to mice induced anxiety-like behavior in recipients. Detailed analysis of gut microbiota composition revealed lower abundances of Verrucomicrobia, Akkermansia, Bifidobacterium, and Butyricimonas, and higher abundances of Deferribacteres, Allobaculum, Bacteroides, and Clostridium in mice that received FMT from GAD patients. MiRNA analysis identified five key miRNAs affecting GAD pathogenesis, including mmu-miR-10a-5p, mmu-miR-1224-5p, mmu-miR-218-5p, mmu-miR-10b-5p, and mmu-miR-488-3p. Notably, mmu-miR-488-3p showed a strong negative correlation with Verrucomicrobia and Akkermansia.

Conclusion

This study demonstrates that anxiety-like behavior induced by human FMT can be transmitted through gut microbiota and is associated with miRNA expression in the prefrontal cortex. It is inferred that the reduction of Akkermansia caused by FMT from GAD patients leads to the upregulation of mmu-miR-488-3p expression, resulting in the downregulation of its downstream target gene Creb1 and interference with its related signaling pathway. These findings highlight the gut microbiota's crucial role in the GAD pathophysiology.

The role of epigenetics in anxiety disorders

Anxiety disorders (ADs) are extremely common psychiatric conditions that frequently co-occur with other physical and mental disorders. The pathophysiology of ADs is multifaceted and involves intricate connections among biological elements, environmental stimuli, and psychological mechanisms. Recent discoveries have highlighted the significance of epigenetics in bridging the gap between multiple risk factors that contribute to ADs and expanding our understanding of the pathomechanisms underlying ADs. Epigenetics is the study of how changes in the environment and behavior can have an impact on gene function. Indeed, researchers have found that epigenetic mechanisms can affect how genes are activated or inactivated, as well as whether they are expressed. Such mechanisms may also affect how ADs form and are protected. That is, the bulk of pharmacological trials evaluating epigenetic treatments for the treatment of ADs have used histone deacetylase inhibitors (HDACi), yielding promising outcomes in both preclinical and clinical studies. This review will provide an outline of how epigenetic pathways can be used to treat ADs or lessen their risk. It will also present the findings from preclinical and clinical trials that are currently available on the use of epigenetic drugs to treat ADs.

Differentiation value of miR-26b for major depressive disorder, schizophrenia, generalized anxiety disorder

Introduction

First episode and drug naive schizophrenia (SZ) patients comorbid with major depressive episode and generalized anxiety disorder (GAD) comorbid with major depressive disorder (MDD) are common in clinical practice, overlapping symptomatology during first presentation of MDD, SZ and GAD challenged the diagnostic process.

Materials and Methods

This study aimed to investigate the differentiation value of peripheral microRNA-26b expression in 52 patients of MDD, SZ, and GAD, respectively, and 52 controls. Quantitative real-time reverse transcription polymerase chain reaction was used to further verify aberrant miRNAs of previous identified in MDD and investigate expression level of these peripheral miRNAs in SZ and GAD.

Results

The expression levels of miR-26b and miR-4743 were significantly upregulated and of miR-4498, miR-4485, and miR-1972 had no significant difference. There were no significant differences of expression levels of miR-26b, miR-4498, miR-4485, and miR-1972 except miR-4743 between SZ patients and control group and of miR-26b, miR-1972, miR-4498, and miR-4485 between GAD group and the controls. The receiver operating characteristic (ROC) curve of miR-26b in MDD patients showed that its sensitivity and specificity for diagnosis were 0.540 and 0.830, respectively, with the area under curve (AUC) being 0.728; the ROC of miR-26b for SZ and MDD differentiation showed that its sensitivity and specificity were 0.580 and 0.710, respectively, with AUC being 0.631; the ROC of miR-26b for GAD and MDD differentiation suggested that sensitivity and specificity were 0.560 and 0.750, respectively, with AUC being 0.637.

Conclusion

MiR-26b might have potential value of differentiation biomarker for MDD, SZ, and GAD.

Role of microRNA in Endocrine Disruptor-Induced Immunomodulation of Metabolic Health

The prevalence of poor metabolic health is growing exponentially worldwide. This condition is associated with complex comorbidities that lead to a compromised quality of life. One of the contributing factors recently gaining attention is exposure to environmental chemicals, such as endocrine-disrupting chemicals (EDCs). Considerable evidence suggests that EDCs can alter the endocrine system through immunomodulation. More concerning, EDC exposure during the fetal development stage has prominent adverse effects later in life, which may pass on to subsequent generations. Although the mechanism of action for this phenomenon is mostly unexplored, recent reports implicate that non-coding RNAs, such as microRNAs (miRs), may play a vital role in this scenario. MiRs are significant contributors in post-transcriptional regulation of gene expression. Studies demonstrating the immunomodulation of EDCs via miRs in metabolic health or towards the Developmental Origins of Health and Disease (DOHaD) Hypothesis are still deficient. The aim of the current review was to focus on studies that demonstrate the impact of EDCs primarily on innate immunity and the potential role of miRs in metabolic health.

A microRNA Prognostic Signature in Patients with Diffuse Intrinsic Pontine Gliomas through Non-Invasive Liquid Biopsy

Simple Summary

Diffuse intrinsic pontine glioma (DIPG) is a neuro-radiologically defined tumor of the brainstem, primarily affecting children, with most diagnoses occurring between 5 and 7 years of age. Surgical removal in DIPGs is not feasible. Subsequent tumor progression is almost universal and no biomarker for predicting the course of the disease has entered into clinical practice so far. Under these premises, it is essential to develop reliable biomarkers that are able to improve outcomes and stratify patients using non-invasive methods to determine tumor profiles. We designed a study assessing circulating miRNA expression by a high-throughput platform and divided patients into training and validation phases in order to disclose a potential signature with clinical impact. Our results for the first time have proved the usefulness of blood-circulating nucleic acids as powerful, easy-to-assay molecular markers of disease status in DIPG.

Abstract

Diffuse midline gliomas (DMGs) originate in the thalamus, brainstem, cerebellum and spine. This entity includes tumors that infiltrate the pons, called diffuse intrinsic pontine gliomas (DIPGs), with a rapid onset and devastating neurological symptoms. Since surgical removal in DIPGs is not feasible, the purpose of this study was to profile circulating miRNA expression in DIPG patients in an effort to identify a non-invasive prognostic signature with clinical impact. Using a high-throughput platform, miRNA expression was profiled in serum samples collected at the time of MRI diagnosis and prior to radiation and/or systemic therapy from 47 patients enrolled in clinical studies, combining nimotuzumab and vinorelbine with concomitant radiation. With progression-free survival as the primary endpoint, a semi-supervised learning approach was used to identify a signature that was also tested taking overall survival as the clinical endpoint. A signature comprising 13 circulating miRNAs was identified in the training set (n = 23) as being able to stratify patients by risk of disease progression (log-rank p = 0.00014; HR = 7.99, 95% CI 2.38–26.87). When challenged in a separate validation set (n = 24), it confirmed its ability to predict progression (log-rank p = 0.00026; HR = 5.51, 95% CI 2.03–14.9). The value of our signature was also confirmed when overall survival was considered (log-rank p = 0.0021, HR = 4.12, 95% CI 1.57–10.8). We have identified and validated a prognostic marker based on the expression of 13 circulating miRNAs that can shed light on a patient’s risk of progression. This is the first demonstration of the usefulness of nucleic acids circulating in the blood as powerful, easy-to-assay molecular markers of disease status in DIPG. This study provides Class II evidence that a signature based on 13 circulating miRNAs is associated with the risk of disease progression.

Challenges in Analyzing Functional Epigenetic Data in Perspective of Adolescent Psychiatric Health

The formative period of adolescence plays a crucial role in the development of skills and abilities for adulthood. Adolescents who are affected by mental health conditions are at risk of suicide and social and academic impairments. Gene-environment complementary contributions to the molecular mechanisms involved in psychiatric disorders have emphasized the need to analyze epigenetic marks such as DNA methylation (DNAm) and non-coding RNAs. However, the large and diverse bioinformatic and statistical methods, referring to the confounders of the statistical models, application of multiple-testing adjustment methods, questions regarding the correlation of DNAm across tissues, and sex-dependent differences in results, have raised challenges regarding the interpretation of the results. Based on the example of generalized anxiety disorder (GAD) and depressive disorder (MDD), we shed light on the current knowledge and usage of methodological tools in analyzing epigenetics. Statistical robustness is an essential prerequisite for a better understanding and interpretation of epigenetic modifications and helps to find novel targets for personalized therapeutics in psychiatric diseases.

The Role of MicroRNA and Microbiota in Depression and Anxiety

Depression and anxiety are devastating disorders. Understanding the mechanisms that underlie the development of depression and anxiety can provide new hints on novel treatments and preventive strategies. Here, we summarize the latest findings reporting the novel roles of gut microbiota and microRNAs (miRNAs) in the pathophysiology of depression and anxiety. The crosstalk between gut microbiota and the brain has been reported to contribute to these pathologies. It is currently known that some miRNAs can regulate bacterial growth and gene transcription while also modulate the gut microbiota composition, suggesting the importance of miRNAs in gut and brain health. Treatment and prevention strategies for neuropsychiatric diseases, such as physical exercise, diet, and probiotics, can modulate the gut microbiota composition and miRNAs expressions. Nonetheless, there are critical questions to be addressed to understand further the mechanisms involved in the interaction between the gut microbiota and miRNAs in the brain. This review summarizes the recent findings of the potential roles of microbiota and miRNA on the neuropathology of depression and anxiety, and its potential as treatment strategies.

The Molecular Basis of Resilience: A Narrative Review

Resilience refers to the adaptability of a person - an ability to "bounce-back" from stressors. We question if resilience can be strengthened, potentially to decrease the risk of stress-related disorders. Unfortunately, the molecular origins of resilience are complicated and not yet well understood. In this review, we examine the various physiological biomarkers of resilience, including the associated genes, epigenetic changes, and protein biomarkers associated with resilient phenotypes. In addition to assessing biomarkers that may indicate higher levels of resilience, we also review at length the many biomarkers that confer lower levels of resilience and may lead to disorders of low resilience, such as anxiety and depression. This large and encompassing review may help to identify the possible therapeutic targets of resilience. Hopefully these studies will lead to a future where stress-related disorders can be prevented, rather than treated.

Obesity and Poststroke Fatigue: A 2-Year Longitudinal Study

Introduction

Obesity is associated with fatigue in many diseases, but the correlation between obesity and poststroke fatigue (PSF) is unclear. The study aimed to investigate the relationship between body mass index (BMI) and the occurrence of and recovery from PSF.

Methods

Within 3 days of the onset of ischemic stroke, patients were consecutively recruited. We assessed PSF at admission and at 6, 12, and 24 months with the Fatigue Severity Scale (FSS). Multivariable logistic regression and restricted cubic spline function were used to explore the relationships between baseline BMI and the risk of PSF at different time points. The correlation between baseline BMI and the dynamic changes in the natural logarithm transformation of the FSS (lnFSS) score during the follow-up period was analyzed by the piecewise linear mixed-effects model.

Results

A total of 1026 stroke patients were included. Multivariable analyses indicated that obesity was associated with a decreased risk of early PSF (fatigue diagnosed at baseline) [odds ratio (OR) 0.61, 95% confidence interval (CI) 0.41–0.93] but an increased risk of late PSF (fatigue diagnosed 6 months after the index stroke) (OR 1.63, 95% CI 1.06–2.50 for 6 months; OR 1.87, 95% CI 1.18–2.96 for 12 months; OR 2.11, 95% CI 1.28–3.49 for 24 months). Longitudinal analyses indicated that in the late stage of fatigue, the higher the BMI category, the slower the rate of decrease was for the FSS score.

Conclusion

Obese patients are less likely to develop fatigue in the acute stage of ischemic stroke. However, they are more prone to late fatigue and exhibit a slower decline in the FSS score in the long term.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40120-021-00276-x.

Stressful life events can predict post-stroke fatigue in patients with ischemic stroke

OBJECTIVE

To investigate whether stressful life events (SLEs) can predict post-stroke fatigue (PSF) in patients with acute ischemic stroke (AIS).

METHODS

This prospective cohort study included data from patients with AIS who were followed up to 2-year interview. PSF was assessed at admission and at 6 (n = 916), 12 (n = 880), and 24 (n = 857) months with the fatigue severity scale (FSS). SLEs were measured with the Social Readjustment Rating Scale questionnaire at 6, 12 and 24 months' interview.

RESULTS

A significant dose-response association was found between SLEs and FSS score across all examined time-points: compared with those did not experience SLEs, FSS score was higher for those experiencing SLEs ≥3 at 6 months (β 0.53, 95% CI 0.28-0.78), 12 months (β 0.54, 95% CI 0.30-0.78) and 24 months (β 0.48, 95% CI 0.29-0.68). Longitudinal analyses indicated a significantly positive relationship between the number of SLEs and FSS score (SLEs: ≥3 vs. 0, β 0.14, 95% CI 0.09-0.19). Moreover, a distinct interaction of follow-up time and SLE numbers on FSS score was observed (p < 0.05), which means elevated exposure to SLEs during follow-up was associated with a lower rate of fatigue decline. A similar association was found in SLE load analysis.

CONCLUSION

Patients with severe fatigue were more likely to report increased number of SLEs in the previous 6 months, which could suggest that a non-specific stressful event leads to an extra burden to an already vulnerable psychological system.

Sex-specific effects of social defeat stress on miRNA expression in the anterior BNST

Women are more likely to suffer from stress-related affective disorders than men, but the underlying mechanisms of sex differences remain unclear. Previous works show that microRNA (miRNA) profiles are altered in stressed animals and patients with depression and anxiety disorders. In this study, we investigated how miRNA expression in the anterior bed nucleus of stria terminalis (BNST) was affected by social defeat stress in female and male California mice (Peromyscus californicus). We performed sequencing to identify miRNA transcripts in the whole brain and anterior BNST followed by qPCR analysis to compare miRNA expression between control and stressed animals. The results showed that social defeat stress induced sex-specific miRNA expression changes in the anterior BNST. Let-7a, let-7f and miR-181a-5p were upregulated in stressed female but not male mice. Our study provided evidence that social stress produces distinct molecular responses in the BNST of males and females.

The Potential Role of Epigenetic Drugs in the Treatment of Anxiety Disorders

There is increasing evidence that abnormalities in epigenetic mechanisms of gene expression contribute to the pathogenesis of anxiety disorders (ADs). This article discusses the role of epigenetic mechanisms of gene expression in the pathogenesis of ADs. It also discusses the data so far obtained from preclinical and clinical trials on the use of epigenetic drugs for treating ADs. Most drug trials investigating the use of epigenetic drugs for treating ADs have used histone deacetylase inhibitors (HDACi). HDACi are showing favorable results in both preclinical and clinical drug trials for treating ADs. However, at present the mode of action of HDACi in ADs is not clear. More work needs to be done to elucidate how epigenetic dysregulation contributes to the pathogenesis of ADs. More work also needs to be done on the mode of action of HDACi in alleviating the signs and symptoms of ADs.

Role of MicroRNAs in Anxiety and Anxiety-Related Disorders

MicroRNAs as critical regulators of gene expression important for functions including neuronal development, synapse formation, and synaptic plasticity have been linked with the regulation of neurobiological systems that underlie anxiety processing in the brain. In this chapter, we give an update on associative evidence linking regulation of microRNAs with anxiety- and trauma-related disorders. Moving beyond correlative research, functional studies have emerged recently that explore causal relationships between microRNA expression and anxiety-like behavior. It has been demonstrated that experimental up- or downregulation of the candidate microRNAs in important nodes of the anxiety neurocircuitry can indeed modulate anxiety-related behavior in animal models. Improved methodologies for assessing microRNA-mediated modulation have aided such functional studies, revealing a number of anxiety-regulating microRNAs including miR-15a, miR-17-92, miR-34, miR-101, miR-124, miR-135, and miR-155. Important functional target genes of these identified microRNAs are associated with specific neurotransmitter/neuromodulator signaling, neurotrophin (e.g., BDNF) expression and other aspects of synaptic plasticity, as well as with stress-regulatory/hypothalamic-pituitary-axis function. Furthermore, microRNAs have been revealed that are regulated in distinct brain regions following various anxiety-attenuating strategies. These include pharmacological treatments such as antidepressants and other drugs, as well as non-pharmacological interventions such as fear extinction/exposure therapy or positive stimuli such as exposure to environmental enrichment. These are first indications for a role for microRNAs in the mechanism of action of anxiolytic treatments. As research continues, there is much hope that a deeper understanding of the microRNA-mediated mechanisms underlying anxiety-related disorders could open up possibilities for future novel biomarker and treatment strategies.

Altered expression of microRNA-223 in the plasma of patients with first-episode schizophrenia and its possible relation to neuronal migration-related genes

Recent studies have shown that microRNAs (miRNAs) play a role as regulators of neurodevelopment by modulating gene expression. Altered miRNA expression has been reported in various psychiatric disorders, including schizophrenia. However, the changes in the miRNA expression profile that occur during the initial stage of schizophrenia have not been fully investigated. To explore the global alterations in miRNA expression profiles that may be associated with the onset of schizophrenia, we first profiled miRNA expression in plasma from 17 patients with first-episode schizophrenia and 17 healthy controls using microarray analysis. Among the miRNAs that showed robust changes, the elevated expression of has-miR-223-3p (miR-223) was validated via quantitative reverse transcription-polymerase chain reaction (qRT-PCR) using another independent sample set of 21 schizophrenia patients and 21 controls. To identify the putative targets of miR-223, we conducted a genome-wide gene expression analysis in neuronally differentiated SK-N-SH cells with stable miR-223 overexpression and an in silico analysis. We found that the mRNA expression levels of four genes related to the cytoskeleton or cell migration were significantly downregulated in miR-223-overexpressing cells, possibly due to interactions with miR-223. The in silico analysis suggested the presence of miR-223 target sites in these four genes. Lastly, a luciferase assay confirmed that miR-223 directly interacted with the 3' untranslated regions (UTRs) of all four genes. Our results reveal an increase in miR-223 in plasma during both the first episode and the later stage of schizophrenia, which may affect the expression of cell migration-related genes targeted by miR-223.

Depressed TSH level as a predictor of poststroke fatigue in patients with acute ischemic stroke

Objective

To investigate whether thyroid function profiles can predict poststroke fatigue (PSF) in patients with acute ischemic stroke.

Methods

Patients with stroke were consecutively recruited within 3 days of onset in Jinling Hospital. Serum levels of thyroid hormones, thyroid antibodies, hematologic indexes, and biochemical indexes were measured on admission. Fatigue was scored using the Fatigue Severity Scale. Associations were analyzed with multivariate regression and restricted cubic splines.

Results

Of the 704 patients with stroke, 292 (41.5%) were diagnosed with fatigue in the acute stage and 224 (35.3%) 6 months after the index stroke. The serum levels of thyroid-stimulating hormone (TSH) were inversely associated with the risk of PSF in both the acute phase and at follow-up evaluations after adjusting for potential confounders (odds ratio 0.30, 95% confidence interval 0.24–0.37 in the acute phase, and odds ratio 0.70, 95% confidence interval 0.58–0.84 at follow-up). The subgroup analysis indicated that in the acute phase of ischemic stroke, TSH was associated with severity of PSF in the groups with euthyroidism (β = −0.70, p < 0.001), subclinical hypothyroidism (β = −0.44, p < 0.001), and low-T3 syndrome (β = −0.34, p = 0.008). Higher TSH was associated with better Fatigue Severity Scale scores in patients with low-T3 syndrome 6 months after the index stroke (β = −0.35, p = 0.01). Furthermore, in the group with low-T3 syndrome, FT3 serum level could also indicate a higher risk of PSF (β = −2.54, p < 0.001 in the acute phase, and β = −2.67, p < 0.001 at follow-up).

Conclusion

Thyroid function profiles may predict fatigue after acute ischemic stroke, suggesting that neuroendocrine responses could have a role in PSF.

Epigenetic Inheritance: Concepts, Mechanisms and Perspectives

Parents’ stressful experiences can influence an offspring’s vulnerability to many pathological conditions, including psychopathologies, and their effects may even endure for several generations. Nevertheless, the cause of this phenomenon has not been determined, and only recently have scientists turned to epigenetics to answer this question. There is extensive literature on epigenetics, but no consensus exists with regard to how and what can (and must) be considered to study and define epigenetics processes and their inheritance. In this work, we aimed to clarify and systematize these concepts. To this end, we analyzed the dynamics of epigenetic changes over time in detail and defined three types of epigenetics: a direct form of epigenetics (DE) and two indirect epigenetic processes—within (WIE) and across (AIE). DE refers to changes that occur in the lifespan of an individual, due to direct experiences with his environment. WIE concerns changes that occur inside of the womb, due to events during gestation. Finally, AIE defines changes that affect the individual’s predecessors (parents, grandparents, etc.), due to events that occur even long before conception and that are somehow (e.g., through gametes, the intrauterine environment setting) transmitted across generations. This distinction allows us to organize the main body of epigenetic evidence according to these categories and then focus on the latter (AIE), referring to it as a faster route of informational transmission across generations—compared with genetic inheritance—that guides human evolution in a Lamarckian (i.e., experience-dependent) manner. Of the molecular processes that are implicated in this phenomenon, well-known (methylation) and novel (non-coding RNA, ncRNA) regulatory mechanisms are converging. Our discussion of the chief methods that are used to study epigenetic inheritance highlights the most compelling technical and theoretical problems of this discipline. Experimental suggestions to expand this field are provided, and their practical and ethical implications are discussed extensively.

Biological markers of generalized anxiety disorder

Generalized anxiety disorder (GAD) is a prevalent and highly disabling mental health condition; however, there is still much to learn with regard to pertinent biomarkers, as well as diagnosis, made more difficult by the marked and common overlap of GAD with affective and anxiety disorders. Recently, intensive research efforts have focused on GAD, applying neuroimaging, genetic, and blood-based approaches toward discovery of pathogenetic and treatment-related biomarkers. In this paper, we review the large amount of available data, and we focus in particular on evidence from neuroimaging, genetic, and neurochemical measurements in GAD in order to better understand potential biomarkers involved in its etiology and treatment. Overall, the majority of these studies have produced results that are solitary findings, sometimes inconsistent and not clearly replicable. For these reasons, they have not yet been translated into clinical practice. Therefore, further research efforts are needed to distinguish GAD from other mental disorders and to provide new biological insights into its pathogenesis and treatment.

Imaging and Genetic Approaches to Inform Biomarkers for Anxiety Disorders, Obsessive-Compulsive Disorders, and PSTD

Anxiety disorders are the most common mental health problem in the world and also claim the highest health care cost among various neuropsychiatric disorders. Anxiety disorders have a chronic and recurrent course and cause significantly negative impacts on patients' social, personal, and occupational functioning as well as quality of life. Despite their high prevalence rates, anxiety disorders have often been under-diagnosed or misdiagnosed, and consequently under-treated. Even with the correct diagnosis, anxiety disorders are known to be difficult to treat successfully. In order to implement better strategies in diagnosis, prognosis, treatment decision, and early prevention for anxiety disorders, tremendous efforts have been put into studies using genetic and neuroimaging techniques to advance our understandings of the underlying biological mechanisms. In addition to anxiety disorders including panic disorder, generalised anxiety disorder (GAD), specific phobias, social anxiety disorders (SAD), due to overlapping symptom dimensions, obsessive-compulsive disorder (OCD), and post-traumatic stress disorder (PTSD) (which were removed from the anxiety disorder category in DSM-5 to become separate categories) are also included for review of relevant genetic and neuroimaging findings. Although the number of genetic or neuroimaging studies focusing on anxiety disorders is relatively small compare to other psychiatric disorders such as psychotic disorders or mood disorders, various structural abnormalities in the grey or white matter, functional alterations of activity during resting-state or task conditions, molecular changes of neurotransmitter receptors or transporters, and genetic associations have all been reported. With continuing effort, further genetic and neuroimaging research may potentially lead to clinically useful biomarkers for the prevention, diagnosis, and management of these disorders.