Fornix microalterations associated with early trauma in panic disorder

Monoamine Oxidase: A Potential Link in Papez Circuit to Generalized Anxiety Disorders

Anxiety is a common mental illness that affects a large number of people around the world, and its treatment is often based on the use of pharmacological substances such as benzodiazepines, serotonin, and 5-hydroxytyrosine (MAO) neurotransmitters. MAO neurotransmitters levels are deciding factors in the biological effects. This review summarizes the current understanding of the MAO system and its role in the modulation of anxiety-related brain circuits and behavior. The MAO-A polymorphisms have been implicated in the susceptibility to generalized anxiety disorder (GAD) in several investigations. The 5-HT system is involved in a wide range of physiological and behavioral processes, involving anxiety, aggressiveness, stress reactions, and other elements of emotional intensity. Among these, 5-HT, NA, and DA are the traditional 5-HT neurons that govern a range of biological activities, including sleep, alertness, eating, thermoregulation, pains, emotion, and memory, as anticipated considering their broad projection distribution in distinct brain locations. The DNMTs (DNA methyltransferase) protein family, which increasingly leads a prominent role in epigenetics, is connected with lower transcriptional activity and activates DNA methylation. In this paper, we provide an overview of the current state of the art in the elucidation of the brain's complex functions in the regulation of anxiety.

Early Trauma Subtypes are Differentially Related to Anxiety Symptomatology and Suicidal Ideation in Panic Disorder

OBJECTIVE

Early trauma significantly affects the severity of panic disorder (PD) symptoms and suicidal ideation. However, few studies have explored the specific effects of different early trauma subtypes on PD. This study analyzed how childhood trauma subtypes, including general, physical, emotional, and sexual, influence panic and phobia levels and suicidal ideation in adults with PD and healthy controls (HCs).

METHODS

In total, 455 adults with PD and 149 HCs participated in this study. The independent variables were sociodemographic and clinical variables such as coping strategies and early trauma subtypes from the Early Trauma Inventory Self Report-Short Form. The dependent variables were the Albany Panic and Phobia Questionnaire (APPQ), the Panic Disorder Severity Scale, and the Scale for Suicide Ideation (SSI).

RESULTS

Early emotional trauma significantly influenced the APPQ scores, whereas early physical trauma significantly influenced the SSI scores in patients with PD. However, in HCs, only early emotional trauma was significantly associated with the APPQ and SSI scores.

CONCLUSION

These findings highlight the influence of early trauma subtypes on the phobic symptom severity of PD and suicidal ideation among patients with PD. Early emotional trauma is associated with the severity of phobic symptoms, whereas early physical trauma is associated with suicidal ideation, suggesting distinct clinical outcomes based on the type of trauma in patients with PD.

Altered DNA Methylation of the Serotonin Transporter Gene Associated with Early Life Stress and White Matter Microalterations in Korean Patients with Panic Disorder

INTRODUCTION

Changes in the DNA methylation of 5-HTTLPR are associated with the pathophysiology of panic disorder (PD). This study was conducted to investigate the association between stressful life events and the level of 5-HTTLPR methylation in patients with PD. We also examined whether these factors were associated with white matter alterations in psychological trauma-related regions.

METHODS

The participants comprised 232 patients with PD and 93 healthy adults of Korean descent. DNA methylation levels of five cytosine-phosphate-guanine (CpG) sites in the 5-HTTLPR region were analyzed. Voxel-wise statistical analysis of diffusion tensor imaging data was performed within the trauma-related regions.

RESULTS

PD patients showed significantly lower levels of the DNA methylation at 5-HTTLPR 5 CpG sites than healthy controls. In patients with PD, the DNA methylation levels at 5-HTTLPR 5 CpG sites showed significant negative association with the parental separation-related psychological distress, and positive correlations with the fractional anisotropy values of the superior longitudinal fasciculus (SLF) which might be related to trait anxiety.

CONCLUSION

Early life stress was significantly associated with DNA methylation levels at 5-HTTLPR related to the decreased white matter integrity in the SLF region in PD. Decreased white matter connectivity in the SLF might be related to trait anxiety and is vital to the pathophysiology of PD.

Associations of maternal emotion regulation with child white matter connectivity in Black American mother-child dyads

Parental emotion regulation plays a major role in parent-child interactions, and in turn, neural plasticity in children, particularly during sensitive developmental periods. However, little is known about how parental emotion dysregulation is associated with variation in children's brain structure, which was the goal of this study. Forty-five Black American mother-child dyads were recruited from an intergenerational trauma study; emotion regulation in mothers and their children (age 8-13 years) was assessed. Diffusion-weighted images were collected in children; deterministic tractography was used to reconstruct pathways of relevance to emotion regulation. Metrics of white matter connectivity [fractional anisotropy (FA), mean diffusivity (MD)] were extracted for pathways. Socio-economic variables were also included in statistical models. Maternal emotion dysregulation was the strongest predictor of child fornix MD (r = .35, p = .001), indicating that more severe emotion dysregulation in mothers corresponded with lower fornix connectivity in children. Maternal impulsivity was a strong predictor of child fornix MD (r = .51, p < .001). Maternal emotion dysregulation may adversely influence connectivity of the child.s fornix, a hippocampal-striatal pathway implicated in reward processes; these associations remained even after accounting for other socio-environmental factors. Dysregulated maternal emotions may uniquely impact children's adaptation to trauma/stress by affecting networks that support appetitive processing.

Prediction of prognosis in patients with panic disorder using pre-treatment brain white matter features

BACKGROUND

The early identification of patients with panic disorder (PD) with a poor prognosis is important for improving treatment outcomes; however, it is challenging due to a lack of objective biomarkers. We investigated the reliability of characterizing structural white matter (WM) connectivity and its ability to predict PD prognosis after pharmacotherapy.

METHODS

A total of 138 patients (59 men) with PD and 153 healthy controls (HCs; 73 men) participated in this study. PD symptom severity was measured using the Panic Disorder Severity Scale (PDSS) at baseline and follow-up periods of 8 weeks, 6 months, and 1 year. The least absolute shrinkage and selection operator (Lasso) was utilized to identify prognosis-related WM regions on diffusion imaging features.

RESULTS

Lasso identified seven prognosis-related WM regions: the bilateral posterior corona radiata, bilateral posterior limb of the internal capsule, the left retrolenticular part of the internal capsule, the left sagittal stratum, and the right fornix/stria terminalis. Some of these regions showed lower mean fractional anisotropy (FA) values in patients with PD than in HCs. The predicted PDSS scores using FA from these regions consistently correlated with the actual prognosis in all periods.

LIMITATIONS

This study had limited ability to evaluate individual longitudinal changes in detail owing to the data acquisition time and brain atlas resolution.

CONCLUSIONS

Our findings suggest the possibility of using structural WM connectivity as a biomarker for the clinical characterization of PD. Our findings will expand our understanding of the neurobiology of PD and improve biomarker-based prognosis prediction in clinical practice.

Subiculum - BNST Structural Connectivity in Humans and Macaques

Invasive tract-tracing studies in rodents implicate a direct connection between the subiculum and bed nucleus of the stria terminalis (BNST) as a key component of neural pathways mediating hippocampal regulation of the Hypothalamic-Pituitary-Adrenal (HPA) axis. A clear characterisation of the connections linking the subiculum and BNST in humans and non-human primates is lacking. To address this, we first delineated the projections from the subiculum to the BNST using anterograde tracers injected into macaque monkeys, revealing evidence for a monosynaptic subiculum-BNST projection involving the fornix. Second, we used in vivo diffusion MRI tractography in macaques and humans to demonstrate substantial subiculum complex connectivity to the BNST in both species. This connection was primarily carried by the fornix, with additional connectivity via the amygdala, consistent with rodent anatomy. Third, utilising the twin-based nature of our human sample, we found that microstructural properties of these tracts were moderately heritable (h² ∼ 0.5). In a final analysis, we found no evidence of any significant association between subiculum complex-BNST tract microstructure and indices of perceived stress/dispositional negativity and alcohol use, derived from principal component analysis decomposition of self-report data. Our findings address a key translational gap in our knowledge of the neurocircuitry regulating stress.

The mediating role of transmembrane protein 132D methylation in predicting the occurrence of panic disorder in physical abuse

OBJECTIVE

Genome Wide Association study (GWAS) has revealed that the transmembrane protein 132D (TMEM132D) is a gene of sensitive for panic disorder (PD). As the main type of childhood trauma experience, childhood abuse has become a public health issue attracting much attention at home and abroad, and has been proved to be a risk factor for the onset of PD. However, how it affects the occurrence and development of panic disorder has not yet been revealed. We examined the relationship between TMEM132D methylation, childhood abuse and symptoms based on this finding.

MATERIALS AND METHODS

Thirty-two patients with PD and 22 healthy controls (HCs) were recruited after age, gender, and the education level were matched. The DNA methylation levels of CpG sites across the genome were examined with genomic DNA samples (PD, N = 32, controls, N = 22) extracted from subjects' elbow venous blood. A mediation model was used to explore the relationship between the methylation degree of different CpG sites and childhood maltreatment and clinical symptoms.

RESULTS

We found that the PD group had significantly lower methylation at CpG1, CpG2, CpG3, CpG4, CpG5, CpG6, CpG7, CpG8, CpG11, CpG14, and CpG18 than did the HCs (p < 0.05). The CpG2 (r = 0.5953, p = 0.0117) site in the priming region of TEME132D gene were positively associated with PDSS score. The CpG2 (r = 0.4889, p = 0.046) site in the priming region of TEME132D gene were positively associated with physical abuse. Furthermore, path analyses showed that the methylation of CpG2 of TMEM132D played a fully mediating role in the relationship between physical abuse and PD symptom severity (95.

CONCLUSION

Childhood abuse experiences, especially physical abuse, are significantly related to PD. The methylation of CpG2 of TMEM132D was shown to have a fully mediating effect between panic disorder and physical abuse. The interaction between TMEM132D methylation and physical abuse can predict panic disorder.

The interaction effect of early trauma exposure and a diagnosis of panic disorder on cortical thickness

BACKGROUND

Early trauma (ET) is a risk factor for adult psychiatric disorders. ET exposure is known to cause structural brain alterations, particularly in the fronto-temporo-limbic circuitry. ET-related effects on brain development may differ based on individual characteristics and cause different psychiatric outcomes. We investigated the interaction effect of ET exposure and panic disorder (PD) on cortical thickness.

METHODS

Sixty-six participants with PD and 66 healthy controls were enrolled. High-resolution T1-weighted images were acquired, and a whole-brain vertex-based analysis was performed to estimate cortical thickness. The Early Trauma Inventory Self Report-Short Form, Anxiety Sensitivity Inventory-Revised, Panic Disorder Severity Scale, Beck Depression Inventory-II, and Beck Anxiety Inventory were administered.

RESULTS

There was a significant interaction between ET exposure and PD on the mean cortical thickness in the bilateral insula and right pars triangularis. An exploratory correlational analysis revealed a positive correlation between the mean cortical thickness in the left insula and severity of anxiety sensitivity to cardiovascular symptoms in participants with PD.

LIMITATIONS

Our findings may be affected by recall bias because this study is limited by its retrospective cross-sectional design.

CONCLUSIONS

Our findings suggest that ET exposure may affect brain structures differently based on a diagnosis of PD. Furthermore, individual variations in brain alterations after ET may confer trait vulnerability that triggers the development of PD. Future longitudinal studies are warranted to elucidate the neurobiological mechanisms underlying ET and psychiatric outcomes.

Early Trauma Is Associated with Poor Pharmacological Treatment Response in Patients with Panic Disorder

OBJECTIVE

Pharmacotherapy is established as an effective method for reducing symptoms of panic disorder (PD). However, about 20-40% of PD patients are treatment-resistant. Predictors of pharmacotherapy outcomes for PD patients are needed.

METHODS

This study included 152 PD patients to measure the clinical severities of PD symptoms and used the Early Trauma Inventory (ETI) to measure early trauma. Treatment response was defined as a 40% reduction in the total Panic Disorder Severity Scale score from baseline. We measured the treatment responses at 8 weeks and 6 months. Binary logistic regression was used to predict treatment response after controlling for confounding variables.

RESULTS

Early sexual trauma alone was associated with poor treatment response at 8 weeks. However, at 6 months, the total ETI score was associated with an unfavorable treatment response.

CONCLUSION

Therefore, our study suggests that clinicians need to be aware of a history of early trauma to optimize treatment outcomes for PD patients.

Biomarkers in Panic Disorder

Background:

Panic disorder (PD) is a kind of anxiety disorder that impacts the life quality and functional perspectives in patients. However, the pathophysiological study of PD seems still inadequate and many unresolved issues need to be clarified.

Objectives:

In this review article of biomarkers in PD, the investigator will focus on the findings of magnetic resonance imaging (MRI) of the brain in the pathophysiology study. The MRI biomarkers would be divided into several categories, on the basis of structural and functional perspectives.

Methods:

The structural category would include the gray matter and white matter tract studies. The functional category would consist of functional MRI (fMRI), resting-state fMRI (Rs-fMRI), and magnetic resonance spectroscopy (MRS). The PD biomarkers revealed by the above methodologies would be discussed in this article.

Results:

For the gray matter perspectives, the PD patients would have alterations in the volumes of fear network structures, such as the amygdala, parahippocampal gyrus, thalamus, anterior cingulate cortex, insula, and frontal regions. For the white matter tract studies, the PD patients seemed to have alterations in the fasciculus linking the fear network regions, such as the anterior thalamic radiation, uncinate fasciculus, fronto-occipital fasciculus, and superior longitudinal fasciculus. For the fMRI studies in PD, the significant results also focused on the fear network regions, such as the amygdala, hippocampus, thalamus, insula, and frontal regions. For the Rs-fMRI studies, PD patients seemed to have alterations in the regions of the default mode network and fear network model. At last, the MRS results showed alterations in neuron metabolites of the hippocampus, amygdala, occipital cortex, and frontal regions.

Conclusion:

The MRI biomarkers in PD might be compatible with the extended fear network model hypothesis in PD, which included the amygdala, hippocampus, thalamus, insula, frontal regions, and sensory-related cortex.

Dissecting the Fornix in Basic Memory Processes and Neuropsychiatric Disease: A Review

Background: The fornix is the primary axonal tract of the hippocampus, connecting it to modulatory subcortical structures. This review reveals that fornix damage causes cognitive deficits that closely mirror those resulting from hippocampal lesions. Methods: We reviewed the literature on the fornix, spanning non-human animal lesion research, clinical case studies of human patients with fornix damage, as well as diffusion-weighted imaging (DWI) work that evaluates fornix microstructure in vivo. Results: The fornix is essential for memory formation because it serves as the conduit for theta rhythms and acetylcholine, as well as providing mnemonic representations to deep brain structures that guide motivated behavior, such as when and where to eat. In rodents and non-human primates, fornix lesions lead to deficits in conditioning, reversal learning, and navigation. In humans, damage to the fornix manifests as anterograde amnesia. DWI research reveals that the fornix plays a key role in mild cognitive impairment and Alzheimer's Disease, and can potentially predict conversion from the former to the latter. Emerging DWI findings link perturbations in this structure to schizophrenia, mood disorders, and eating disorders. Cutting-edge research has investigated how deep brain stimulation of the fornix can potentially attenuate memory loss, control epileptic seizures, and even improve mood. Conclusions: The fornix is essential to a fully functioning memory system and is implicated in nearly all neurological functions that rely on the hippocampus. Future research needs to use optimized DWI methods to study the fornix in vivo, which we discuss, given the difficult nature of fornix reconstruction. Impact Statement The fornix is a white matter tract that connects the hippocampus to several subcortical brain regions and is pivotal for episodic memory functioning. Functionally, the fornix transmits essential neurotransmitters, as well as theta rhythms, to the hippocampus. In addition, it is the conduit by which memories guide decisions. The fornix is biomedically important because lesions to this tract result in irreversible anterograde amnesia. Research using in vivo imaging methods has linked fornix pathology to cognitive aging, mild cognitive impairment, psychosis, epilepsy, and, importantly, Alzheimer's Disease.

Early sexual trauma is related with the tapetum in patients with panic disorder

BACKGROUND

Early trauma exposure is suggested to confer a greater risk for the development of panic disorder (PD) by altering neurodevelopmental processes. A body of studies have shown that white matter microstructures, particularly in the fronto-limbic and callosal regions, could be affected by a history of early trauma in patients with PD. The tapetum, the extended posterior part of the corpus callosum connecting the bilateral temporal lobes, has not yet been studied regarding its relationship with early trauma, especially sexual one.

METHODS

Seventy participants with PD, sixty age- and sex-matched healthy controls were enrolled. The Early Trauma Inventory Self Report-Short Form (ETISR-SF), Neuroticism Scale, and Panic Disorder Severity Scale (PDSS) were administered. Voxel-wise statistical analysis of diffusion tensor imaging data was performed within the bilateral tapetum regions using Tract-Based Spatial Statistics (TBSS).

RESULTS

In participants with PD, higher levels of sexual trauma were significantly associated with the increased fractional anisotropies (FAs) in a cluster of the right tapetum. Exploratory correlation analysis revealed that FAs in this cluster were significantly correlated with higher neuroticism and poorer treatment response after one year of pharmacotherapy. No significant correlation was found between FAs of the right tapetum cluster and the PDSS scores.

LIMITATIONS

The possibility of retrospective recall bias for early trauma cannot be completely ruled out.

CONCLUSIONS

The findings of this study suggest that the right tapetum may serve as a potential neural marker of early sexual trauma in patients with PD and contribute to personal vulnerability and poorer treatment outcome after pharmacotherapy.

White Matter-Based Structural Brain Network of Anxiety

Anxiety disorders are characterized by excessive fear and anxiety and related behavioral disturbances. Because diffusion tensor imaging is sensitive to detect subtle pathology of the brain, it has been used to characterize differences in white matter microstructure for a broad spectrum of psychiatric disorders. The neurobiological underpinnings of a trait anxiety seem to be associated with the uncinate fasciculus, a major pathway between the amygdala and orbitofrontal cortex. Apparent WM micro-alterations in patients with panic disorder are present in diverse and widespread regions, although alterations vary in terms of clinical symptom severity and comorbidities. Social anxiety disorder is associated with structural dysconnectivity in a fronto-limbic network consistent with reduced fractional anisotropy values in uncinate fasciculus and inferior longitudinal fasciculus. The pathogenesis of obsessive-compulsive disorder may include abnormal findings in not only the fronto-striato-thalamic circuit but also the posterior and temporal regions of forceps major and cingulum bundle. Studies of white matter status in anxiety revealed overlapping patterns of front-cortical and fronto-limbic changes with uncinate fasciculus and cingulum alterations a frequent component.

Individualized prediction of dispositional worry using white matter connectivity

BACKGROUND

Excessive worry is a defining feature of generalized anxiety disorder and is present in a wide range of other psychiatric conditions. Therefore, individualized predictions of worry propensity could be highly relevant in clinical practice, with respect to the assessment of worry symptom severity at the individual level.

METHODS

We applied a multivariate machine learning approach to predict dispositional worry based on microstructural integrity of white matter (WM) tracts.

RESULTS

We demonstrated that the machine learning model was able to decode individual dispositional worry scores from microstructural properties in widely distributed WM tracts (mean absolute error = 10.46, p < 0.001; root mean squared error = 12.82, p < 0.001; prediction R2 = 0.17, p < 0.001). WM tracts that contributed to worry prediction included the posterior limb of internal capsule, anterior corona radiate, and cerebral peduncle, as well as the corticolimbic pathways (e.g. uncinate fasciculus, cingulum, and fornix) already known to be critical for emotion processing and regulation.

CONCLUSIONS

The current work thus elucidates potential neuromarkers for clinical assessment of worry symptoms across a wide range of psychiatric disorders. In addition, the identification of widely distributed pathways underlying worry propensity serves to better improve the understanding of the neurobiological mechanisms associated with worry.