Changes in Cerebral Cortex and Limbic Brain Functions after Short-Term Paroxetine Treatment in Panic Disorder: An [F]FDG-PET Pilot Study

Cerebral Metabolic Signature of Chronic Benzodiazepine Use in Nondemented Older Adults: An FDG-PET Study in the MEMENTO Cohort

OBJECTIVE

We sought to examine the association between chronic Benzodiazepine (BZD) use and brain metabolism obtained from 2-deoxy-2-fluoro-D-glucose (FDG) positron emission tomography (PET) in the MEMENTO clinical cohort of nondemented older adults with an isolated memory complaint or mild cognitive impairment at baseline.

METHODS

Our analysis focused on 3 levels: (1) the global mean brain standardized uptake value (SUVR), (2) the Alzheimer's disease (AD)-specific regions of interest (ROIs), and (3) the ratio of total SUVR on the brain and different anatomical ROIs. Cerebral metabolism was obtained from 2-deoxy-2-fluoro-D-glucose-FDG-PET and compared between chronic BZD users and nonusers using multiple linear regressions adjusted for age, sex, education, APOE ε 4 copy number, cognitive and neuropsychiatric assessments, history of major depressive episodes and antidepressant use.

RESULTS

We found that the SUVR was significantly higher in chronic BZD users (n = 192) than in nonusers (n = 1,122) in the whole brain (beta = 0.03; p = 0.038) and in the right amygdala (beta = 0.32; p = 0.012). Trends were observed for the half-lives of BZDs (short- and long-acting BZDs) (p = 0.051) and Z-drug hypnotic treatments (p = 0.060) on the SUVR of the right amygdala. We found no significant association in the other ROIs.

CONCLUSION

Our study is the first to find a greater global metabolism in chronic BZD users and a specific greater metabolism in the right amygdala. Because the acute administration of BZDs tends to reduce brain metabolism, these findings may correspond to a compensatory mechanism while the brain adapts with global metabolism upregulation, with a specific focus on the right amygdala.

Breaking the Fear Barrier: Aberrant Activity of Fear Networks as a Prognostic Biomarker in Patients with Panic Disorder Normalized by Pharmacotherapy

Panic disorder (PD) is a prevalent type of anxiety disorder. Previous studies have reported abnormal brain activity in the fear network of patients with PD. Nonetheless, it remains uncertain whether pharmacotherapy can effectively normalize these abnormalities. This longitudinal resting-state functional magnetic resonance imaging study aimed to investigate the spontaneous neural activity in patients with PD and its changes after pharmacotherapy, with a focus on determining whether it could predict treatment response. The study included 54 drug-naive patients with PD and 54 healthy controls (HCs). Spontaneous neural activity was measured using regional homogeneity (ReHo). Additionally, support vector regression (SVR) was employed to predict treatment response from ReHo. At baseline, PD patients had aberrant ReHo in the fear network compared to HCs. After 4 weeks of paroxetine treatment (20 mg/day), a significant increase in ReHo was observed in the left fusiform gyrus, which had shown reduced ReHo before treatment. The SVR analysis showed significantly positive correlations (p < 0.0001) between the predicted and actual reduction rates of the severity of anxiety and depressive symptoms. Here, we show patients with PD had abnormal spontaneous neural activities in the fear networks. Furthermore, these abnormal spontaneous neural activities can be partially normalized by pharmacotherapy and serve as candidate predictors of treatment response. Gaining insight into the trajectories of brain activity normalization following treatment holds the potential to provide vital insights for managing PD.

Abnormal functional connectivity of brain regions associated with fear network model in panic disorder

Background: Patients with panic disorder (PD) have an abnormal function in brain regions related to fear network is well recognised. However, the traditional fear network model (FNM) which was based on animals' horrible behaviours has been found that it's not enough to explain the pathological mechanism of PD. This study aims to explore brain regions' abnormalities in the new advanced FNM, and estimate whether it can better explain PD.Methods: Magnetic resonance imaging resting-state scans were acquired in 40 patients with PD (35 drug-naïve and 5 drug-free) and 40 healthy controls (HCs). Twelve brain regions in the advanced FNM were chosen as regions of interest (ROIs) to examine the group difference in the ROIs and whole-brain resting-state functional connectivity (rsFC).Results: We found significantly increased thalamic rsFC with the insula, compared with HCs. And it was significantly correlated with HAMA-somatic score. We also found increased thalamic rsFC with occipital gyrus, temporal gyrus, and frontal gyrus when compared with HCs.Conclusions: Taken together, PD patients exhibit abnormal rsFC alterations within the advanced FNM, especially the increased rsFC within thalamus-insula loop, suggesting that excessive sensitivity to external information plays an important role in PD. The advanced FNM may provide a fuller explanation about PD.

The alterations of degree centrality in the frontal lobe of patients with panic disorder

Objective: The brain network in panic disorder (PD) is still an intriguing issue for research. In this study, we hoped to investigate the role of DC (degree centrality) for the pathophysiology of PD, especially for the fear network. Methods: We enrolled 60 patients with PD and 60 controls in the current study. The gender and age were matched for two groups. All participants received the resting-state functional magnetic resonance imaging to survey the baseline brain activity. Then the DC values of all participants were using REST toolbox. We also compared the DC values between PD and controls. The statistical threshold was set as FDR (false discovery rate) < 0.05. Results: The DC values were significantly lower in the right superior frontal gyrus of PD patients compared to controls (FDR < 0.05). In addition, a negative correlation between the DC values and panic severity was observed in the right superior frontal gyrus and left inferior frontal gyrus. However, there was no significant association between the DC values and illness duration. Conclusion: The DC seemed significantly altered in the frontal lobe of PD patients. The role of the frontal lobe might be more emphasized in the pathophysiology research for PD.

Role of Basolateral Amygdalar Somatostatin 2 Receptors in a Rat Model of Chronic Anxiety

Repeated exposure to stress has been implicated in inducing chronic anxiety states. Stress related increases in anxiety responses are likely mediated by activation of corticotropin-releasing factor receptors (CRFR) in the amygdala, particularly the basolateral amygdala (BLA). Within the BLA, acute injections of the CRFR agonist urocortin 1 (Ucn1) leads to acute anxiety, whereas repeated daily injections of subthreshold-doses of Ucn1 produces a long-lasting, persistent anxiety-like phenotype, a phenomenon referred to as Ucn1-priming. Relative gene expressions from the BLA of vehicle and Ucn1-primed rats were analyzed with quantitative RT-PCR using a predesigned panel of 82 neuroscience-related genes. Compared to vehicle-primed rats, only expression of the somatostatin receptor 2 gene (Sstr2) was significantly reduced in the BLA of Ucn1-primed rats. The contribution of Sstr2 on an anxiety phenotype was tested by injecting a Sstr2 antagonist into the BLA in un-primed rats. The Sstr2 antagonist increased anxiety-like behavior. Notably, pretreatment with Sstr2 agonist injected into the BLA blocked anxiety-inducing effects of acute Ucn1 BLA-injections and delayed anxiety expression during Ucn1-priming. However, concomitant Sstr2 agonist pretreatment during Ucn-1 priming did not prevent either the development of a chronic anxiety state or a reduction of BLA Sstr2 expression induced by priming. The data demonstrate that the persistent anxiety-like phenotype observed with Ucn1-priming in the BLA is associated with a selective reduction of Sstr2 gene expression. Although Sstr2 activation in the BLA blocks acute anxiogenic effects of stress and down-regulation of BLA Sstr2, it does not suppress the long-term consequences of prolonged exposure to stress-related challenges.

Neural correlates of negative and disease-specific emotional stimuli in panic disorder: a functional magnetic resonance imaging study

OBJECTIVE

Decades of research have highlighted the involvement of the prefrontal cortex, anterior cingulated cortex, and limbic areas (amygdala) in panic disorder (PD). However, little attention has been given specifically to the inferior frontal gyrus. The current study aimed to investigate the neural substrates, including the inferior frontal gyrus, of both panic-related and negative conditions among individuals with PD and healthy controls.

METHODS

We examined 13 medication-free PD patients and 14 healthy controls with functional magnetic resonance imaging (fMRI) during exposure to negative and neutral pictures and a set of specific panic-related pictures.

RESULTS

Subtraction between the conditions indicated activation of the left amygdala region and the right inferior frontal gyrus in PD patients during the specific panic-related condition, whereas the left amygdalar region and left inferior frontal gyrus were activated during the negative condition in controls.

CONCLUSION

These results suggest that in patients with PD, a prominent bottom-up process is involved in specific panic-related conditions, which might be associated with weak modulation of the left frontal area. These data add to our current understanding of the neural correlates of PD and can contribute to future clinical interventions targeting the functional reestablishment of these regions.

Neural correlates of emotional processing in panic disorder: A mini review of functional magnetic resonance imaging studies

BACKGROUND

Panic Disorder (PD) is mainly characterized by recurrent unexpected panic attacks. Although the presence of emotional functioning deficits in PD is well established, their neuronal bases are still less known. Therefore, in this review, we aim to summarize the available functional Magnetic Resonance Imaging (fMRI) studies investigating the neural correlates associated with the processing of facial emotional expressions in patients with PD.

METHODS

A comprehensive search on PubMed was performed and 10 fMRI studies meeting our inclusion criteria were included in this review.

RESULTS

The majority of the studies reported selective deficits in key brain regions within the prefronto-limbic network in PD patients. Specifically, a mixed picture of hyperactivation and hypoactivation patterns were observed in limbic regions, including the amygdala and the anterior cingulate cortex (ACC), as well as in areas within the prefrontal cortex (PFC), either during negative or positive valenced stimuli, as compared to healthy controls (HC) or other anxiety disorders.

LIMITATIONS

The limited number of studies and the clinical and methodological heterogeneity make it difficult to draw definite conclusions on the neural mechanism of emotional processing associated with PD.

CONCLUSION

Although the results of the available evidence suggest the presence of selective dysfunctions in regions within the cortico-limbic network in PD patients during processing of emotional stimuli, the direction of these abnormalities is still unclear. Therefore, future larger and more homogeneous studies are needed to elucidate the neural mechanisms underpinning the emotional processing dysfunctions often observed in PD patients.

Altered resting-state fMRI signals and network topological properties of bipolar depression patients with anxiety symptoms

BACKGROUND

This study aims to explore the changes in functional neuroimaging in bipolar depression patients with anxiety symptoms (BDP-A).

METHODS

Forty-five BDP-A patients, 22 bipolar depression patients without anxiety symptoms (BDP-NA), and 48 healthy controls (HC) were finally involved. The low-frequency oscillation characteristics, functional connectivity (FC), and network properties among the three groups of participants were analyzed.

RESULTS

Compared with the BDP-NA group, BDP-A patients exhibited significantly decreased amplitude of low-frequency fluctuation (ALFF) in the left middle frontal gyrus (MFG), superior occipital gyrus, and inferior parietal, but supramarginal and angular gyri (IPL). Enhanced FC from left IPL to middle temporal gyrus, from left precentral gyrus (PreCG) to bilateral angular gyri, medial superior frontal gyrus, and left superior frontal gyrus (SFG)/MFG were also revealed. Compared with HC, the BDP-A group showed remarkably increased ALFF in the left MFG/PreCG, right superior parietal gyrus, while decreased ALFF in the left inferior frontal gyrus, opercular part, and SFG. In addition, higher regional homogeneity in the left MFG/PreCG was found.

LIMITATIONS

The limitations are as follows: (1) relatively small sample size; (2) not all the patients were drug-naive; (3) lack of pure anxiety disorder patients as a controlled group; (4) mental health conditions of HC were not systemic evaluated.

CONCLUSIONS

BDP-A patients showed significant differences in resting-state fMRI properties when compared with BDP-NA or HC group. These results may infer the dysfunction of the dorsal attention network, the default network, and the fronto-limbic system as well as disrupted brain network efficiency in BDP-A patients.

Base on concept of traditional Chinese medicine: Experimental studies on efficacy of BIOCERAMIC Resonance to alleviate drug withdrawal symptoms

Those who are challenged by dependency on prescription drugs or suffer drug addictions have few options available to them for recovery, such as psychotherapy and physiotherapy. Here we present a new approach with clinical examples involving stimulant addiction or overdose of hypnotic drugs that were received BIOCERAMIC Resonance, which was developed based on concept of 12 meridian channels of traditional Chinese medicine, and has successful withdrawal or dose reduction benefits. We describe the whole process and the clinical outcome. And by help of our previous publication on functional MRI, we discuss the possible brain locations response to BIOCERAMIC Resonance that may be corresponding to the beneficial effects of relief of depression, sleep deprivation and other mental symptoms that associate with substance abuse and withdrawal effects. We suggest this could be potentially widely application on substances abuse.

Fear Network Model in Panic Disorder: The Past and the Future

The core concept for pathophysiology in panic disorder (PD) is the fear network model (FNM). The alterations in FNM might be linked with disturbances in the autonomic nervous system (ANS), which is a common phenomenon in PD. The traditional FNM included the frontal and limbic regions, which were dysregulated in the feedback mechanism for cognitive control of frontal lobe over the primitive response of limbic system. The exaggerated responses of limbic system are also associated with dysregulation in the neurotransmitter system. The neuroimaging studies also corresponded to FNM concept. However, more extended areas of FNM have been discovered in recent imaging studies, such as sensory regions of occipital, parietal cortex and temporal cortex and insula. The insula might integrate the filtered sensory information via thalamus from the visuospatial and other sensory modalities related to occipital, parietal and temporal lobes. In this review article, the traditional and advanced FNM would be discussed. I would also focus on the current evidences of insula, temporal, parietal and occipital lobes in the pathophysiology. In addition, the white matter and functional connectome studies would be reviewed to support the concept of advanced FNM. An emerging dysregulation model of fronto-limbic-insula and temporooccipito-parietal areas might be revealed according to the combined results of recent neuroimaging studies. The future delineation of advanced FNM model can be beneficial from more extensive and advanced studies focusing on the additional sensory regions of occipital, parietal and temporal cortex to confirm the role of advanced FNM in the pathophysiology of PD.

Biological markers for anxiety disorders, OCD and PTSD - a consensus statement. Part I: Neuroimaging and genetics

OBJECTIVES

Biomarkers are defined as anatomical, biochemical or physiological traits that are specific to certain disorders or syndromes. The objective of this paper is to summarise the current knowledge of biomarkers for anxiety disorders, obsessive-compulsive disorder (OCD) and post-traumatic stress disorder (PTSD).

METHODS

Findings in biomarker research were reviewed by a task force of international experts in the field, consisting of members of the World Federation of Societies for Biological Psychiatry Task Force on Biological Markers and of the European College of Neuropsychopharmacology Anxiety Disorders Research Network.

RESULTS

The present article (Part I) summarises findings on potential biomarkers in neuroimaging studies, including structural brain morphology, functional magnetic resonance imaging and techniques for measuring metabolic changes, including positron emission tomography and others. Furthermore, this review reports on the clinical and molecular genetic findings of family, twin, linkage, association and genome-wide association studies. Part II of the review focuses on neurochemistry, neurophysiology and neurocognition.

CONCLUSIONS

Although at present, none of the putative biomarkers is sufficient and specific as a diagnostic tool, an abundance of high-quality research has accumulated that will improve our understanding of the neurobiological causes of anxiety disorders, OCD and PTSD.

The Explorative Analysis to Revise Fear Network Model for Panic Disorder: Functional Connectome Statistics

Functional connectome analysis in panic disorder (PDO) is a relatively new field for research. We tried to investigate the functional connectome alterations in PDO to re-examine the precision and role of fear network model for the pathophysiology of PDO.We enrolled 53 PDO patients and 54 controls with imaging data in this study. After preprocessing, we calculated the connectivity matrix of functional connectivity in whole brain for each subject. Then network-based statistics (The University of Melbourne and Melbourne Health, Australia) of connectome was used to perform group comparisons between patients and controls. The correlation between network measures of significant subnetwork and illness duration or severity of PDO was also performed.Within the 6 network models, only 1 network survived after multiple corrections. We found decreased functional connectivity in the edges between the following nodes: the left parahippocampal gyrus, bilateral precentral gyri, bilateral middle cingulate gyri, bilateral supramarginal gyri, bilateral calcarine fissures, and right lingual gyrus. The central hubs were the left parahippocampal gyrus and left precentral gyrus. The importance of limbic areas and connection with sensory and motor regions might shed light on the revision of fear network model for the pathophysiology of PDO.

Facing the fear--clinical and neural effects of cognitive behavioural and pharmacotherapy in panic disorder with agoraphobia

INTRODUCTION

Cognitive behavioural therapy (CBT) and pharmacological treatment with selective serotonin or serotonin-noradrenalin reuptake inhibitors (SSRI/SSNRI) are regarded as efficacious treatments for panic disorder with agoraphobia (PD/AG). However, little is known about treatment-specific effects on symptoms and neurofunctional correlates.

EXPERIMENTAL PROCEDURES

We used a comparative design with PD/AG patients receiving either two types of CBT (therapist-guided (n=29) or non-guided exposure (n=22)) or pharmacological treatment (SSRI/SSNRI; n=28) as well as a wait-list control group (WL; n=15) to investigate differential treatment effects in general aspects of fear and depression (Hamilton Anxiety Rating Scale HAM-A and Beck Depression Inventory BDI), disorder-specific symptoms (Mobility Inventory MI, Panic and Agoraphobia Scale subscale panic attacks PAS-panic, Anxiety Sensitivity Index ASI, rating of agoraphobic stimuli) and neurofunctional substrates during symptom provocation (Westphal-Paradigm) using functional magnetic resonance imaging (fMRI). Comparisons of neural activation patterns also included healthy controls (n=29).

RESULTS

Both treatments led to a significantly greater reduction in panic attacks, depression and general anxiety than the WL group. The CBT groups, in particular, the therapist-guided arm, had a significantly greater decrease in avoidance, fear of phobic situations and anxiety symptoms and reduction in bilateral amygdala activation while the processing of agoraphobia-related pictures compared to the SSRI/SSNRI and WL groups.

DISCUSSION

This study demonstrates that therapist-guided CBT leads to a more pronounced short-term impact on agoraphobic psychopathology and supports the assumption of the amygdala as a central structure in a complex fear processing system as well as the amygdala's involvement in the fear system's sensitivity to treatment.

The Effects of Taekwondo Training on Brain Connectivity and Body Intelligence

OBJECTIVE

Many studies have reported that Taekwondo training could improve body perception, control and brain activity, as assessed with an electroencephalogram. This study aimed to assess body intelligence and brain connectivity in children with Taekwondo training as compared to children without Taekwondo training.

METHODS

Fifteen children with Taekwondo training (TKD) and 13 age- and sex-matched children who had no previous experience of Taekwondo training (controls) were recruited. Body intelligence, clinical characteristics and brain connectivity in all children were assessed with the Body Intelligence Scale (BIS), self-report, and resting state functional magnetic resonance imaging.

RESULTS

The mean BIS score in the TKD group was higher than that in the control group. The TKD group showed increased low-frequency fluctuations in the right frontal precentral gyrus and the right parietal precuneus, compared to the control group. The TKD group showed positive cerebellum vermis (lobe VII) seed to the right frontal, left frontal, and left parietal lobe. The control group showed positive cerebellum seed to the left frontal, parietal, and occipital cortex. Relative to the control group, the TKD group showed increased functional connectivity from cerebellum seed to the right inferior frontal gyrus.

CONCLUSION

To the best of our knowledge, this is the first study to assess the effect of Taekwondo training on brain connectivity in children. Taekwondo training improved body intelligence and brain connectivity from the cerebellum to the parietal and frontal cortex.

Neurostructural abnormalities in pediatric anxiety disorders

Functional neuroimaging studies have consistently demonstrated abnormalities in fear and threat processing systems in youth with anxiety disorders; however, the structural neuroanatomy of these systems in children and adolescents remains largely unknown. Using voxel-based morphometry (VBM), gray matter volumes were compared between 38 medication-free patients with anxiety disorders (generalized anxiety disorder; social phobia; separation anxiety disorder, mean age: 14.4±3 years) and 27 comparison subjects (mean age: 14.8±4 years). Compared to healthy subjects, youth with anxiety disorders had larger gray matter volumes in the dorsal anterior cingulate and had decreased gray matter volumes in the inferior frontal gyrus (ventrolateral prefrontal cortex), postcentral gyrus, and cuneus/precuneus. These data suggest the presence of structural differences in regions previously implicated in the processing and regulation of fear in pediatric patients with anxiety disorders.

Olfactory functioning in panic disorder

BACKGROUND

The olfactory function in panic disorder (PD) has been scarcely approached in the literature. The purpose of this paper is to study this question by focusing on the olfactory sensitivity (i.e. detection threshold), the reactivity to odors, and the odor awareness in patients suffering from PD.

METHODS

41 patients with PD and 41 healthy controls performed Sniffin׳ Sticks Test (threshold subtest) and completed the Affective Impact of Odors scale (AIO), the Relational Scale of Olfaction (EROL) and the Odor Awareness Scale (OAS). Clinical symptoms rating scales were concurrently obtained.

RESULTS

PD patients showed lower olfactory detection thresholds (i.e. higher sensitivity) along with an enhanced reactivity to odors as well as a greater olfactory awareness compared to the healthy controls. The severity of PD was significantly associated with the olfactory questionnaires ratings, but not with the detection ability. Olfactory measures were intercorrelated in most cases.

LIMITATIONS

i) The results of the olfactory sensitivity are limited to one odorant (phenyl ethyl alcohol) and thus may not be generalizable to other odorants. ii) As comorbid Axis II disorders were not screened, it is not possible to exclude the influence of personality traits in our results. iii) The involvement of the medications in some olfactory outcomes cannot be ruled out.

CONCLUSION

The current findings highlight the importance of the olfactory function in PD as patients appeared to be highly sensitive, reactive and aware of odors. These results are discussed in the light of the common neural substrates involved in the olfactory processing and in the pathophysiology of PD, and also related to the clinical features of this disorder.

Brain involvement in patients with inflammatory bowel disease: a voxel-based morphometry and diffusion tensor imaging study

OBJECTIVES

To investigate structural brain changes in inflammatory bowel disease (IBD).

METHODS

Brain magnetic resonance imaging (MRI) was performed on 18 IBD patients (aged 45.16 ± 14.71 years) and 20 aged-matched control subjects. The imaging protocol consisted of a sagittal-FLAIR, a T1-weighted high-resolution three-dimensional spoiled gradient-echo sequence, and a multisession spin-echo echo-planar diffusion-weighted sequence. Differences between patients and controls in brain volume and diffusion indices were evaluated using the voxel-based morphometry (VBM) and tract-based spatial statistics (TBSS) methods, respectively. The presence of white-matter hyperintensities (WMHIs) was evaluated on FLAIR images.

RESULTS

VBM revealed decreased grey matter (GM) volume in patients in the fusiform and the inferior temporal gyrus bilaterally, the right precentral gyrus, the right supplementary motor area, the right middle frontal gyrus and the left superior parietal gyrus (p < 0.05). TBSS showed decreased axial diffusivity (AD) in the right corticospinal tract and the right superior longitudinal fasciculus in patients compared with controls. A larger number of WMHIs was observed in patients (p < 0.05).

CONCLUSIONS

Patients with IBD show an increase in WMHIs and GM atrophy, probably related to cerebral vasculitis and ischaemia. Decreased AD in major white matter tracts could be a secondary phenomenon, representing Wallerian degeneration.

KEY POINTS

• There is evidence of central nervous system involvement in IBD. • Diffusion tensor imaging detects microstructural brain abnormalities in IBD. • Voxel based morphometry reveals brain atrophy in IBD.

Functional t1ρ imaging in panic disorder

BACKGROUND

Abnormal brain pH has been suggested to play a critical role in panic disorder. To investigate this possibility, we employed a pH-sensitive magnetic resonance (MR) imaging strategy (T1 relaxation in the rotating frame [T1ρ]) and conventional blood oxygen level-dependent (BOLD) imaging.

METHODS

Thirteen panic disorder participants and 13 matched control subjects were enrolled in the study. T1ρ and BOLD were used to study the functional response to a visual flashing checkerboard and their relationship to panic symptoms assessed using the Beck Anxiety Inventory.

RESULTS

In response to visual stimulation, T1ρ imaging revealed a significantly greater increase in the visual cortex of panic disorder participants. T1ρ also detected a stimulus-evoked decrease in the anterior cingulate cortex. Blood oxygen level-dependent imaging detected no functional differences between groups. The correspondence between panic symptoms and functional T1ρ response identified significant relationships within the left inferior parietal lobe, left middle temporal gyrus, and right insula. No relationships were found between panic symptoms and the BOLD signal.

CONCLUSIONS

The data suggest greater activity-evoked T1ρ changes in the visual cortex and anterior cingulate cortex of panic disorder participants. These observations are consistent with a pH dysregulation in panic disorder. In addition, our data suggest that T1ρ imaging may provide information about panic disorder that is distinct from conventional BOLD imaging and may reflect abnormalities in pH and/or brain metabolism.

Neuroanatomic abnormalities in adolescents with generalized anxiety disorder: a voxel-based morphometry study

BACKGROUND

Despite recent data implicating functional abnormalities in the neurocircuitry underlying emotional processing in pediatric anxiety disorders, little is known regarding neurostructural abnormalities within these systems.

METHODS

Using voxel-based morphometry, gray and white matter volumes were compared in 15 medication-free adolescents with generalized anxiety disorder (GAD; and no comorbid major depressive disorder) and 28 age- and sex-matched healthy comparison subjects.

RESULTS

Compared to healthy adolescents, youth with GAD had larger gray matter volumes in the right precuneus and right precentral gyrus and decreased gray matter volumes in the left orbital gyrus and posterior cingulate. White matter volumes were decreased in the left medial and superior frontal gyrus and were increased in the left inferior temporal gyrus in youth with GAD relative to healthy subjects.

CONCLUSIONS

Adolescents with GAD, who are early in the course of their illness, exhibit abnormalities in neural structures that subserve threat appraisal, modulation of fear responses, attachment, and mentalization.

Changes in gray matter volume of remitted first-episode, drug-naïve, panic disorder patients after 6-week antidepressant therapy

OBJECTIVE

This study aimed to investigate changes in the gray matter volume (GMV) of first-episode, remitted drug-naïve patients under 6 weeks of escitalopram treatment for panic disorder (PD). We also determined any persistent GMV deficits after remission to assess for "state-dependent brain changes" and "trait-like brain changes" for PD.

METHOD

3-Tesla magnetic resonance imaging structural scans were performed on 21 PD patients at baseline and in their remitted state at week 6 of the study. To account for the inter-scanner bias, 21 healthy controls were also scanned twice within 6 weeks. All structural images were processed and analyzed to estimate GMV differences between patients and controls. We utilized optimized voxel-based morphometry with global brain volume, age, and gender as covariates. We also estimated the correlation between improvements in clinical rating scale scores and changes in total gray matter volumes to confirm the results of optimized voxel-based morphometry.

RESULTS

Rating scales of panic symptoms improved significantly (corrected p < 0.001). Remitted patients showed increased GMV in the left superior frontal gyrus (corrected p < 0.05) after escitalopram therapy. There were significant GMV deficits in the right precentral gyrus (corrected p < 0.05) after remission of PD symptoms. Changes in total GMV after remission were correlated with changes in clinical scores (r = 0.638; Spearman's rho p = 0.002).

CONCLUSION

The left superior frontal gyrus (state-dependent brain changes) and the right precentral gyrus (trait-like brain changes) might be implicated in the underlying pathophysiology of PD.

The role of the amygdala in the pathophysiology of panic disorder: evidence from neuroimaging studies

Although the neurobiological mechanisms underlying panic disorder (PD) are not yet clearly understood, increasing amount of evidence from animal and human studies suggests that the amygdala, which plays a pivotal role in neural network of fear and anxiety, has an important role in the pathogenesis of PD. This article aims to (1) review the findings of structural, chemical, and functional neuroimaging studies on PD, (2) relate the amygdala to panic attacks and PD development, (3) discuss the possible causes of amygdalar abnormalities in PD, (4) and suggest directions for future research.

Revise the revised? New dimensions of the neuroanatomical hypothesis of panic disorder

In 2000, Gorman et al. published a widely acknowledged revised version of their 1989 neuroanatomical hypothesis of panic disorder (PD). Herein, a 'fear network' was suggested to mediate fear- and anxiety-related responses: panic attacks result from a dysfunctional coordination of 'upstream' (cortical) and 'downstream' (brainstem) sensory information leading to heightened amygdala activity with subsequent behavioral, autonomic and neuroendocrine activation. Given the emergence of novel imaging methods such as fMRI and the publication of numerous neuroimaging studies regarding PD since 2000, a comprehensive literature search was performed regarding structural (CT, MRI), metabolic (PET, SPECT, MRS) and functional (fMRI, NIRS, EEG) studies on PD, which will be reviewed and critically discussed in relation to the neuroanatomical hypothesis of PD. Recent findings support structural and functional alterations in limbic and cortical structures in PD. Novel insights regarding structural volume increase or reduction, hyper- or hypoactivity, laterality and task-specificity of neural activation patterns emerged. The assumption of a generally hyperactive amygdala in PD seems to apply more to state than trait characteristics of PD, and involvement of further areas in the fear circuit, such as anterior cingulate and insula, is suggested. Furthermore, genetic risk variants have been proposed to partly drive fear network activity. Thus, the present state of knowledge generally supports limbic and cortical prefrontal involvement as originally proposed in the neuroanatomical hypothesis. Some modifications might be suggested regarding a potential extension of the fear circuit, genetic factors shaping neural network activity and neuroanatomically informed clinical subtypes of PD potentially guiding future treatment decisions.