Dysfunction of Resting-State Functional Connectivity of Amygdala Subregions in Drug-Naïve Patients With Generalized Anxiety Disorder

Shared and distinct morphometric similarity network abnormalities in generalized anxiety disorder, posttraumatic stress disorder and social anxiety disorder

BACKGROUND

The high comorbidity and symptom overlap of generalized anxiety disorder (GAD), posttraumatic stress disorder (PTSD), and social anxiety disorder (SAD), has led to the study of their shared and disorder-specific neural substrates. However, the morphometric similarity network (MSN) differences among these disorders remain unknown.

METHODS

MSN derived from T1-weighted images in patients of GAD, PTSD, and SAD, and health controls (HC) using a Siemens 3T magnetic resonance imaging system. Covariance analysis and post hoc tests were used to investigate group differences. In addition, the relationship between MSN and clinical characteristics was analyzed.

RESULTS

Increased morphometric similarity (MS) between left bankssts (BA22, superior temporal cortex, STC) and right precentral gyrus, and decreased MS between left precentral gyrus and right cuneus_part1/part2, and between right rostral middle frontal cortex (rMFC) and right STC were common in GAD and PTSD relative to HC and SAD. Compared to the other three groups, SAD exhibited disorder-specific alterations of increased MS between right rMFC and right STC, and between left cuneus and right inferior parietal cortex. Additionally, increased regional MSN in left precentral gyrus was found in PTSD compared to HC and SAD. A mild positive correlation of the MS value between left bankssts and right precentral gyrus and the Hamilton Anxiety Rating Scale scores (uncorrected p = 0.041) was found in PTSD.

CONCLUSIONS

Our study provides the first evidence for common and distinct brain MSN abnormalities underlying the pathophysiology of GAD, PTSD, and SAD, which may aid in differential diagnosis and determining potential disorder-specific intervention targets.

The Limbic System in Co-Occurring Substance Use and Anxiety Disorders: A Narrative Review Using the RDoC Framework

Substance use disorders (SUDs) and anxiety disorders (ADs) are highly comorbid, a co-occurrence linked to worse clinical outcomes than either condition alone. While the neurobiological mechanisms involved in SUDs and anxiety disorders are intensively studied separately, the mechanisms underlying their comorbidity remain an emerging area of interest. This narrative review explores the neurobiological processes underlying this comorbidity, using the Research Domain Criteria (RDoC) framework to map disruptions in positive valence, negative valence, and cognitive systems across the three stages of the addiction cycle: binge/intoxication, withdrawal/negative affect, and preoccupation/anticipation. Anxiety and substance use play a reciprocal role at each stage of addiction, marked by significant psychosocial impairment and dysregulation in the brain. A more thorough understanding of the neural underpinnings involved in comorbid SUDs and anxiety disorders will contribute to more tailored and effective therapeutic interventions and assessments.

Microbiome Metabolomic Analysis of the Anxiolytic Effect of Baihe Dihuang Decoction in a Rat Model of Chronic Restraint Stress

Purpose

The Baihe Dihuang decoction (BDD) is a representative traditional Chinese medicinal formula that has been used to treat anxiety disorders for thousands of years. This study aimed to reveal mechanisms of anxiolytic effects of BDD with multidimensional omics.

Methods

First, 28-day chronic restraint stress (CRS) was used to create a rat model of anxiety, and the open field test and elevated plus maze were used to assess anxiety-like behavior. Enzyme-linked immunosorbent assay (ELISA), hematoxylin-eosin staining, and immunofluorescence staining were used to evaluate inflammatory response. Besides, 16S rRNA gene sequencing assessed fecal microbiota composition and differential microbiota. Non-targeted metabolomics analysis of feces was performed to determine fecal biomarkers, and targeted metabolomics was used to observe the levels of hippocampus neurotransmitters. Finally, Pearson correlation analysis was used to examine relationships among gut microbiota, fecal metabolites, and neurotransmitters.

Results

BDD significantly improved anxiety-like behaviors in CRS-induced rats and effectively ameliorated hippocampal neuronal damage and abnormal activation of hippocampal microglia. It also had a profound effect on the diversity of microbiota, as evidenced by significant changes in the abundance of 10 potential microbial biomarkers at the genus level. Additionally, BDD led to significant alterations in 18 fecal metabolites and 12 hippocampal neurotransmitters, with the majority of the metabolites implicated in amino acid metabolism pathways such as D-glutamine and D-glutamate, alanine, arginine and proline, and tryptophan metabolism. Furthermore, Pearson analysis showed a strong link among gut microbiota, metabolites, and neurotransmitters during anxiety and BDD treatment.

Conclusion

BDD can effectively improve anxiety-like behaviors by regulating the gut-brain axis, including gut microbiota and metabolite modification, suppression of hippocampal neuronal inflammation, and regulation of neurotransmitters.

RGS14 expression in CA2 hippocampus, amygdala, and basal ganglia: Implications for human brain physiology and disease

RGS14 is a multifunctional scaffolding protein that is highly expressed within postsynaptic spines of pyramidal neurons in hippocampal area CA2. Known roles of RGS14 in CA2 include regulating G protein, H-Ras/ERK, and calcium signaling pathways to serve as a natural suppressor of synaptic plasticity and postsynaptic signaling. RGS14 also shows marked postsynaptic expression in major structures of the limbic system and basal ganglia, including the amygdala and both the ventral and dorsal subdivisions of the striatum. In this review, we discuss the signaling functions of RGS14 and its role in postsynaptic strength (long-term potentiation) and spine structural plasticity in CA2 hippocampal neurons, and how RGS14 suppression of plasticity impacts linked behaviors such as spatial learning, object memory, and fear conditioning. We also review RGS14 expression in the limbic system and basal ganglia and speculate on its possible roles in regulating plasticity in these regions, with a focus on behaviors related to emotion and motivation. Finally, we explore the functional implications of RGS14 in various brain circuits and speculate on its possible roles in certain disease states such as hippocampal seizures, addiction, and anxiety disorders.