Enhanced interhemispheric resting-state functional connectivity of the visual network is an early treatment response of paroxetine in patients with panic disorder

This study aimed to detect alterations in interhemispheric interactions in patients with panic disorder (PD), determine whether such alterations could serve as biomarkers for the diagnosis and prediction of therapeutic outcomes, and map dynamic changes in interhemispheric interactions in patients with PD after treatment. Fifty-four patients with PD and 54 healthy controls (HCs) were enrolled in this study. All participants underwent clinical assessment and a resting-state functional magnetic resonance imaging scan at (i) baseline and (ii) after paroxetine treatment for 4 weeks. A voxel-mirrored homotopic connectivity (VMHC) indicator, support vector machine (SVM), and support vector regression (SVR) were used in this study. Patients with PD showed reduced VMHC in the fusiform, middle temporal/occipital, and postcentral/precentral gyri, relative to those of HCs. After treatment, the patients exhibited enhanced VMHC in the lingual gyrus, relative to the baseline data. The VMHC of the fusiform and postcentral/precentral gyri contributed most to the classification (accuracy = 87.04%). The predicted changes were accessed from the SVR using the aberrant VMHC as features. Positive correlations (p < 0.001) were indicated between the actual and predicted changes in the severity of anxiety. These findings suggest that impaired interhemispheric coordination in the cognitive-sensory network characterized PD and that VMHC can serve as biomarkers and predictors of the efficiency of PD treatment. Enhanced VMHC in the lingual gyrus of patients with PD after treatment implied that pharmacotherapy recruited the visual network in the early stages.

Resting-state cortico-limbic functional connectivity pattern in panic disorder: Relationships with emotion regulation strategy use and symptom severity

Cognitive reappraisal is an effective emotion regulation strategy involving prefrontal cortex (PFC) control of the amygdala. Its aberrant functioning is closely associated with panic disorder (PD). However, the resting-state functional connectivity (rsFC) between the PFC, implicated in cognitive reappraisal, and the amygdala in PD has not been studied. Thus, this study aims to investigate the rsFC patterns and their association with cognitive reappraisal and PD. This study involved 51 participants, including 26 untreated patients with PD and 25 healthy controls (HC). We evaluated the habit of cognitive reappraisal assessment and the severity of PD using neuropsychological and clinical measures. Resting-state fMRI was utilized to evaluate the rsFC pattern between the PFC, engaged in cognitive reappraisal, and the amygdala. Mediation analysis was performed to explore the role of this rsFC in the relationship between cognitive reappraisal and PD severity. PD patients showed reduced rsFC between the PFC and the amygdala compared to HC. This weakened rsFC was associated with the severity of PD symptoms. Moreover, cognitive reappraisal was negatively correlated with PD severity, and mediation analysis indicated that the rsFC of the PFC-amygdala played a mediating role in this association. Abnormal PFC-amygdala rsFC may play a pivotal role in PD development and/or manifestation and mediate the association between cognitive reappraisal and PD severity, potentially serving as a clinical indicator for monitoring and intervention.

Long-term benefits of mindfulness on white matter tracts underlying the cortical midline structures in panic disorder: A 2-year longitudinal study

AIMS

We aimed to examine the long-term benefits of mindfulness-based cognitive therapy (MBCT) on white matter plasticity in the cortical midline structures (CMS) for a period of 2 years in patients with panic disorder and the relationships between white matter changes in the CMS and severity of state and trait symptoms.

METHODS

Seventy-one participants were enrolled and underwent diffusion tensor imaging at baseline and after 2 years (26 who received MBCT as an adjunct to pharmacotherapy [MBCT+PT], 20 treated with pharmacotherapy alone [PT-alone], and 25 healthy controls [HCs]). The severity of symptoms and fractional anisotropy (FA) in white matter regions underlying the CMS were assessed at baseline and 2-year follow-up.

RESULTS

The MBCT+PT group showed better outcomes after 2 years than the PT-alone group. The groups showed different FA changes: the MBCT+PT group showed decreased FA in the left anterior cingulate cortex (ACC); the PT-alone group showed increased FA in the bilateral dorsomedial prefrontal cortex, posterior cingulate cortex (PCC), and precuneus. Decreased white matter FA in the ACC, PCC, and precuneus was associated with improvements in the severity of state and trait symptoms in patients with panic disorder.

CONCLUSION

Alleviation of excessive white matter connectivity in the CMS after MBCT leads to improvements in clinical symptoms and trait vulnerability in patients with panic disorder. Our study provides new evidence for the long-term benefits of MBCT on white matter plasticity and its clinical applicability as a robust treatment for panic disorder.

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.

Impact of childhood trauma on the abnormal functional connectivity of brain regions in the fear network model of panic disorder

BACKGROUND

People who have suffered childhood trauma may be more susceptible to panic disorder (PD). Existing evidence indicates that childhood trauma can significantly impact brain function. Meanwhile, the brain regions involved in the fear network model (FNM) of PD highly overlap with the brain regions affected by childhood trauma. However, it remains unclear whether functional connections between brain regions associated with the FNM in patients with PD are affected by childhood trauma. This study aimed to investigate the effects of childhood trauma on the functional connectivity (FC) of brain regions associated with the FNM in patients with PD.

METHOD

This study recruited 62 patients with PD, including 21 with a high level of childhood trauma (PD_HCT), 41 with a low level of childhood trauma (PD_LCT), and 40 healthy controls (HCs). The patients underwent magnetic resonance imaging resting-state scanning. The amygdala, anterior cingulate, thalamus, and hippocampus were chosen as regions of interest (ROIs) to examine group differences in ROIs and whole-brain resting-state FC (rsFC).

RESULTS

Compared with PD_HCT patients, PD_LCT patients exhibited significantly increased rsFC in the right thalamus, right temporo-occipital middle temporal gyrus, left thalamus, and right temporo-occipital middle temporal gyrus. Compared with HCs, PD_LCT patients had increased rsFC between the right thalamus and the right temporo-occipital middle temporal gyrus.

CONCLUSION

Patients with PD who had suffered high and low levels of childhood trauma were found to exhibit different pathological rsFC alterations in the FNM, suggesting that childhood trauma may be an important risk factor for the development of PD symptoms.

Retinal Changes in Panic Disorder Patients

AIM

Optical coherence tomography (OCT) is a novel method that allows high resolution cross-sectional imaging of biological tissues. It was suggested that changes in the cranial structure or functions would be reflected in the retina. OCT has been an important method in the diagnosis and follow-up of diseases via morphometric or quantitative retinal measurements. Panic disorder (PD) is an anxiety disorder, where free radicals, inflammatory processes and neurotransmitter transmission disorders play a role in the etiology. The present study aimed to demonstrate neurodegeneration in PD by the comparison of PD patient and control OCT data.

MATERIAL AND METHOD

The study group included 21 PD patients who met the study criteria. The control group included 21 healthy individuals without any known psychiatric or organic disease, including eye disease, and gender-matched to the patient group. All participants underwent detailed psychiatric and eye examinations. Central macular thickness (CMT), macular volume (MV), mean and retinal nerve fiber layer thickness (RNFL), ganglion cell layer thickness (GCLT), and central choroidal thickness (CCT) were measured in both eyes of all participants with OCT. A sociodemographic data form, Clinical Global Impression Scale (CGIS), and Panic Disorder Severity Scale (PDSS) were administered to the participants.

RESULTS

In the study, it was determined that the CMT values of the PD patients were lower when compared to the controls in the OCT examination. There was a statistically significant difference between the CMT of the PD patient group and the control group; the CMT was lower in the patient group. There were no significant differences between the groups based on GCLT, RNFL superior, RNFL inferior, RNFL nasal, RNFL temporal, and CCT. There was no significant correlation between CGIS, PDSS scores and OCT measurements.

CONCLUSION

This is the first study in the literature where patients with a PD diagnosis were analyzed based on the OCT method. OCT, which is a simple, noninvasive and relatively inexpensive method that the patient could easily adapt to during imaging, could be employed as a supplementary method in the diagnosis and follow-up of PD patients.

Smaller volume of right hippocampal CA2/3 in patients with panic disorder

The hippocampus is thought to play an important role in conveying contextual information to the amygdala as the neural basis of panic disorder (PD). Previous studies have revealed functional abnormalities in the hippocampus in patients with PD compared with healthy control subjects (HC), but no study has reported volume abnormalities in the hippocampus or evaluated minute structural changes in the hippocampus in such patients. We thus investigated volume abnormalities in the subfields of the hippocampus to better understand the neurobiological basis of PD. The hippocampus was extracted from structural brain magnetic resonance images obtained from 38 patients with PD and 38 HC and then segmented into six subfields. The relative volume of each subfield was compared between the two groups. The severity of symptoms was assessed using the Panic Disorder Severity Scale (PDSS) and social functioning was assessed using the Global Assessment of Functioning (GAF) scale. Our results revealed that patients with PD had a significantly smaller volume of the right cornu ammonis (CA) 2/3 hippocampal subfield compared with HC. No significant associations were found between the volumes of the right CA 2/3 and the PDSS or GAF scores in correlation analyses. In conclusion, CA2/3 is thought to be related to contextual memory function, and our results suggest that this particular hippocampal subfield plays a role in the development of PD symptoms.

Regional cortical thinning and cerebral hypoperfusion in patients with panic disorder

BACKGROUND

Although recent neuroimaging studies have suggested that functional deficits in facial perception are associated with panic disorder (PD), the possibility of cortical thickness and perfusion abnormalities have not been studied in patients with PD. We aimed to investigate alterations in cortical thickness and regional cerebral blood flow (CBF) between PD patients and healthy controls (HCs) using three-dimensional (3D) T1-weighted magnetic resonance imagery (MRI) and 3D arterial spin labeling (ASL) perfusion MRI.

METHOD

An automated surface-based method (Cat12) measured the cortical thickness of each subject. Z-score normalization for CBF maps was used to generate Z-score maps. Statistical comparisons were performed using statistical parametric mapping with two-sample t-tests.

RESULTS

Subjects with PD, unlike HCs, displayed cortical thinning in the right fusiform gyrus (FG). Post hoc analysis also revealed a decreased Z-score in the right FG. There was significant positive correlation between the Z-score and the cortical thickness of the right FG. The cortical thickness and Z-score were negatively correlated with the Panic Disorder Severity Scale and Hamilton Rating Scale for Anxiety scores.

LIMITATIONS

The small sample size may have restricted the identification of additional differences. Other caveats included the use of medication by nine participants.

CONCLUSIONS

These results provide further evidence of the significant role structural and functional deficits in the right FG play in patients with PD. Due to the observed regional specificity, this finding bears important clinical implications for potential treatment strategies.

Neural correlates of subjective arousal and valence in health and panic disorder

Aberrant emotion processing is a core characteristic of panic disorder (PD). Findings concerning the underlying neural pathways remain inconsistent. We applied functional magnetic resonance imaging (fMRI) in the context of a task based on the circumplex model of affect. This model links affective states to two underlying neurophysiological systems: arousal and valence. Twenty-two healthy participants and 20 participants with PD rated arousal and valence in response to affective faces during fMRI. In healthy controls, we found that arousal modulated the hemodynamic response in the parahippocampus, the ventromedial prefrontal cortex and the cuneus during face perception. Valence and extreme ratings of valence modulated the hemodynamic response in temporal, parietal, somatosensory, premotor and cerebellar regions. Comparing healthy controls to participants with PD, we found that healthy controls showed a stronger modulation of the hemodynamic response during face perception associated with extreme ratings of valence in the parahippocampus and the supplementary motor area. This suggests parahippocampal dysfunction in the processing of highly valenced affective faces in PD, which may underlie aberrant contextualization of strong affective stimuli. Our findings need to be interpreted with care as they were adjusted for multiple comparisons using a liberal correction procedure.

In vivo investigation on bio-markers of perimenopausal panic disorder and catgut embedding acupoints mechanism

BACKGROUND

Panic disorder (PD), defined by repeated and unexpected panic attacks, severely affects patients' living quality and social function. Perimenopausal women are high-risk group of PD and suffer greatly from it. Modern medicine therapies for this disorder have many side reactions and poor effects, so nonpharmacological modality is an urgent need. Although acupoint catgut embedding is widely used in clinical practice, there is no persuasive evidence of its effect for perimenopausal PD. The aim of this study is to investigate the effectiveness and safety of acupoint catgut embedding for perimenopausal PD and to elucidate the correlations among brain neural activation, bio-markers (amino acids) and clinical outcomes with radiographic evidence, thus to explore its neural mechanism.

METHODS

The parallel designed, exploratory randomized controlled trial will include 70 outpatients with perimenopausal PD recruited from two hospitals of Chinese Medicine. These subjects will be randomly allocated to an intervention group (Group Embedding) and a control group (Group Medication) in a 1:1 ratio. The subjects in the intervention group will receive acupoint catgut embedding treatment two weeks a time in the following predefined acupuncture points: Shenshu (BL23), Sanyinjiao (SP6), Guanyuan (RN4), Ganshu (BL18), Zusanli (ST36) and Pishu (BL20). The included women of the control group will take 0.4 mg Alprazolam tablet orally, 1 tablet a time, 3 times a day. There is a study period of 3 months and a follow-up period of 1 month for each group. The primary outcomes will be the following therapeutic indexes: the frequency of panic attack, Panic Disorder Severity Score (PDSS), and Panic-associated Symptoms Score (PASS) during the observation period and follow-up period. The changes in Hamilton Anxiety Scale (HAMA) Score and Symptom Checklist 90 (SCL-90) Score will also be compared between these two groups. Additionally, functional magnetic resonance imaging (fMRI) and proton magnetic resonance spectroscopy (1H-MRS) scans will be done before and after the observation period to show cranial neuroimaging changes.

DISCUSSION

We present a study design and rationale to explore the effectiveness and neural mechanism of acupoint catgut embedding for perimenopausal PD. There are still several factors restrict our research such as no unified standard of diagnostic criteria and curative effect evaluation.

TRIAL REGISTRATION

Chinese Clinical Trial Registry, ChiCTR-INR-16009724, registered in November 2016.

Common and different neural markers in major depression and anxiety disorders: A pilot structural magnetic resonance imaging study

Although anxiety and depression often co-occur and share some clinical features, it is still unclear if they are neurobiologically distinct or similar processes. In this study, we explored common and specific cortical morphology alterations in depression and anxiety disorders. Magnetic Resonance Imaging data were acquired from 13 Major Depressive Disorder (MDD), 11 Generalized Anxiety Disorder (GAD), 11 Panic Disorder (PD) patients and 21 healthy controls (HC). Regional cortical thickness, surface area (SA), volume and gyrification were measured and compared among groups. We found left orbitofrontal thinning in all patient groups, as well as disease-specific alterations. MDD showed volume deficits in left precentral gyrus compared to all groups, volume and area deficits in right fusiform gyrus compared to GAD and HC. GAD showed lower SA than MDD and PD in right superior parietal cortex, higher gyrification than HC in right frontal gyrus. PD showed higher gyrification in left superior parietal cortex when compared to MDD and higher SA in left postcentral gyrus compared to all groups. Our results suggest that clinical phenotypic similarities between major depression and anxiety disorders might rely on common prefrontal alterations. Frontotemporal and parietal abnormalities may represent unique biological signatures of depression and anxiety.

Cognitive-behavioral therapy effects on alerting network activity and effective connectivity in panic disorder

Given the particular relevance of arousal and alerting in panic disorder (PD), here the alerting network was investigated (1) contrasting patients with PD and healthy controls, (2) as a function of anxiety sensitivity constituting a dimensional measure of panic-related anxiety, and (3) as a possible correlate of treatment response. Using functional magnetic resonance imaging (fMRI), 45 out-patients with PD (f = 34) and 51 matched healthy controls were investigated for brain activation patterns and effective connectivity (Dynamic Causal Modeling, DCM) while performing the Attention Network Task (ANT). Anxiety sensitivity was ascertained by the Anxiety Sensitivity Index (ASI). Forty patients and 48 controls were re-scanned after a 6 weeks cognitive-behavioral treatment (CBT) or an equivalent waiting time, respectively. In the alerting condition, patients showed decreased activation in fronto-parietal pathways including the middle frontal gyrus and the superior parietal lobule (MFG, SPL). In addition, ASI scores were negatively correlated with connectivity emerging from the SPL, the SFB and the LC and going to the MFG in patients but not in healthy controls. CBT resulted in an increase in middle frontal and parietal activation along with increased connectivity going from the MFG to the SPL. This change in connectivity was positively correlated with reduction in ASI scores. There were no changes in controls. The present findings point to a pathological disintegration of the MFG in a fronto-parietal pathway in the alerting network in PD which was observed to be reversible by a successful CBT intervention.

Abnormal frontal generator during auditory sensory gating in panic disorder: An MEG study

Patients with panic disorder (PD) exhibit abnormalities in early-stage information processing, even for the nonthreatening stimuli. A previous event-related potential study reported that PD patients show a deficit in sensory gating (SG), a protective mechanism of the brain to filter out irrelevant sensory inputs. However, there is no clear understanding about the neural correlates of SG deficits in PD. Moreover, whether SG deficits, if any, are associated with clinical manifestations remain unknown. In this study, 18 patients with PD and 20 age- and gender-matched healthy controls were recruited to perform auditory paired-stimulus paradigm using magnetoencephalographic (MEG) recordings. Results showed that PD patients demonstrated significantly higher M50 SG ratios in the right inferior frontal gyrus (RIFG) and higher M100 SG ratios in both RIFG and right superior temporal gyrus (RSTG) than those of the control group. It was important to note that in the RIFG, the M50 SG ratios correlated significantly with the scores of Body Sensation Questionnaire (BSQ) and Distractibility scale of Sensory Gating Inventory among patients with PD. In conclusion, this study suggests that PD patients exhibited a deficient ability to filter out irrelevant information, and such a defect might lead to cognitive misinterpretation of somatic sensations and distractibility.

Gray matter changes in panic disorder: A voxel-based meta-analysis and meta-analytic connectivity modeling

Magnetic resonance imaging (MRI) studies of panic disorder (PD) have discovered various damaged brain regions, with heterogeneous results across studies. The present study used meta-analytic approaches to discover gray matter (GM) changes consistently detected in PD and to characterize the functional and connectivity profiles of these regions. In the present study we first conducted an activation likelihood estimation (ALE) meta-analysis of eight eligible whole-brain VBM studies. Then, meta-analytic connectivity modeling analyses (MACMs) were used to provide co-atrophy and co-activation profiles across all the experiments stored in BrainMap. Lastly, the co-atrophied and co-activated regions were analyzed using functional decoding to reveal their functions. Lower gray matter volume was found in the bilateral dorsomedial prefrontal cortex (DMPFC), left dorsolateral prefrontal cortex (DLPFC), right insula, right superior temporal gyrus (STG), right middle temporal gyrus (MTG) and right superior orbital frontal cortex (OFC). Significant co-atrophies were found in the STG, DMPFC and OFC and co-activations were found between the left DLPFC and bilateral DMPFC. Decreased gray matter volume in STG, OFC, DLPFC and DMPFC and their co-atrophy and co-activation patterns indicate the damaged higher cognitive functions in PD and suggest that cortical regions are important structural imaging biomarkers in PD.

Thalamic shape and volume abnormalities in female patients with panic disorder

The thalamus is believed to play crucial role in processing viscero-sensory information, and regulating the activity of amygdala in patients with panic disorder (PD). Previous functional neuroimaging studies have detected abnormal activation in the thalamus in patients with PD compared with healthy control subjects (HC). Very few studies, however, have investigated for volumetric abnormalities in the thalamus in patients with PD. Furthermore, to the best of our knowledge, no previous study has investigated for shape abnormalities in the thalamus in patients with PD. Twenty-five patients with PD and 25 HC participants (all female) were recruited for the study. A voxel-wise volume comparison analysis and a vertex-wise shape analysis were conducted to evaluate structural abnormalities in the PD patients compared to HC. The patients with PD demonstrated significant gray matter volume reductions in the thalamus bilaterally, relative to the HC. The shape analysis detected significant inward deformation in some thalamic regions in the PD patients, including the anterior nucleus, mediodorsal nucleus, and pulvinar nucleus. PD patients showed shape deformations in key thalamic regions that are believed to play a role in regulating emotional and cognitive functions.

Smaller volumes in the lateral and basal nuclei of the amygdala in patients with panic disorder

The amygdala plays an important functional role in fear and anxiety. Abnormalities in the amygdala are believed to be involved in the neurobiological basis of panic disorder (PD). Previous structural neuroimaging studies have found global volumetric and morphological abnormalities in the amygdala in patients with PD. Very few studies, however, have explored for structural abnormalities in various amygdala sub-regions, which consist of various sub-nuclei, each with different functions. This study aimed to evaluate for volumetric abnormalities in the amygdala sub-nuclei, in order to provide a better understanding neurobiological basis of PD. Thirty-eight patients with PD and 38 matched healthy control (HC) participants underwent structural MRI scanning. The volume of the whole amygdala, as well as its consistent sub-nuclei, were calculated using FreeSurfer software. Relative volumes of these amygdala sub-regions were compared between the two groups. Results showed significantly smaller volumes in the right lateral and basal nuclei in the patients with PD compared with the HC. Lateral and basal nuclei are thought to play crucial role for processing sensory information related with anxiety and fear. Our results suggest that these particular amygdala sub-regions play a role in the development of PD symptoms.

Reward and loss anticipation in panic disorder: An fMRI study

Anticipatory anxiety and harm avoidance are essential features of panic disorder (PD) and may involve deficits in the reward system of the brain, in particular in the ventral striatum. While neuroimaging studies on PD have focused on fearful and negative affective stimulus processing, no investigations have directly addressed deficits in reward and loss anticipation. To determine whether the ventral striatum shows abnormal neural activity in PD patients during anticipation of loss or gain, an event-related functional magnetic resonance imaging experiment using a monetary incentive delay task was employed in 10 patients with PD and 10 healthy controls. A repeated-measures ANOVA to identify effects of group (PD vs. Control) and condition (anticipation of loss vs. gain vs. neutral outcome) revealed that patients with PD showed significantly reduced bilateral ventral striatal activation during reward anticipation but increased activity during loss anticipation. Within the patient group, the degree of activation in the ventral striatum during loss-anticipation was positively correlated with harm avoidance and negatively correlated with novelty seeking. These findings suggest that behavioural impairments in panic disorder may be related to abnormal neural processing of motivational cues.

Distinct phasic and sustained brain responses and connectivity of amygdala and bed nucleus of the stria terminalis during threat anticipation in panic disorder

BACKGROUND

Panic disorder (PD) patients are constantly concerned about future panic attacks and exhibit general hypersensitivity to unpredictable threat. We aimed to reveal phasic and sustained brain responses and functional connectivity of the amygdala and the bed nucleus of the stria terminalis (BNST) during threat anticipation in PD.

METHODS

Using functional magnetic resonance imaging (fMRI), we investigated 17 PD patients and 19 healthy controls (HC) during anticipation of temporally unpredictable aversive and neutral sounds. We used a phasic and sustained analysis model to disentangle temporally dissociable brain activations.

RESULTS

PD patients compared with HC showed phasic amygdala and sustained BNST responses during anticipation of aversive v. neutral stimuli. Furthermore, increased phasic activation was observed in anterior cingulate cortex (ACC), insula and prefrontal cortex (PFC). Insula and PFC also showed sustained activation. Functional connectivity analyses revealed partly distinct phasic and sustained networks.

CONCLUSIONS

We demonstrate a role for the BNST during unpredictable threat anticipation in PD and provide first evidence for dissociation between phasic amygdala and sustained BNST activation and their functional connectivity. In line with a hypersensitivity to uncertainty in PD, our results suggest time-dependent involvement of brain regions related to fear and anxiety.

Neurobiological and clinical effects of fNIRS-controlled rTMS in patients with panic disorder/agoraphobia during cognitive-behavioural therapy

BACKGROUND

A relevant proportion of patients with panic disorder (PD) does not improve even though they receive state of the art treatment for anxiety disorders such as cognitive-behavioural therapy (CBT). At the same time, it is known, that from a neurobiological point of view, PD patients are often characterised by prefrontal hypoactivation. Intermittent Theta Burst Stimulation (iTBS) is a non-invasive type of neurostimulation which can modulate cortical activity and thus has the potential to normalise prefrontal hypoactivity found in PD. We therefore aimed at investigating the effects of iTBS as an innovative add-on to CBT in the treatment for PD.

METHODS

In this double-blind, bicentric study, 44 PD patients, randomised to sham or verum stimulation, received 15 sessions of iTBS over the left prefrontal cortex (PFC) in addition to 9 weeks of group CBT. Cortical activity during a cognitive as well as an emotional (Emotional Stroop) paradigm was assessed both at baseline and post-iTBS treatment using functional near-infrared spectroscopy (fNIRS) and compared to healthy controls.

RESULTS

In this manuscript we only report the results of the emotional paradigm; for the results of the cognitive paradigm please refer to Deppermann et al. (2014). During the Emotional Stroop test, PD patients showed significantly reduced activation to panic-related compared to neutral stimuli for the left PFC at baseline. Bilateral prefrontal activation for panic-related stimuli significantly increased after verum iTBS only. Clinical ratings significantly improved during CBT and remained stable at follow-up. However, no clinical differences between the verum- and sham-stimulated group were identified, except for a more stable reduction of agoraphobic avoidance during follow-up in the verum iTBS group.

LIMITATIONS

Limitations include insufficient blinding, the missing control for possible state-dependent iTBS effects, and the timing of iTBS application during CBT.

CONCLUSION

Prefrontal hypoactivity in PD patients was normalised by add-on iTBS. Clinical improvement of anxiety symptoms was not affected by iTBS.

Transdiagnostic brain responses to disorder-related threat across four psychiatric disorders

BACKGROUND

There is an ongoing debate whether transdiagnostic neural mechanisms are shared by different anxiety-related disorders or whether different disorders show distinct neural correlates. To investigate this issue, studies controlling for design and stimuli across multiple anxiety-related disorders are needed.

METHOD

The present functional magnetic resonance imaging study investigated neural correlates of visual disorder-related threat processing across unmedicated patients suffering from panic disorder (n = 20), social anxiety disorder (n = 20), dental phobia (n = 16) and post-traumatic stress disorder (n = 11) relative to healthy controls (HC; n = 67). Each patient group and the corresponding HC group saw a tailor-made picture set with 50 disorder-related and 50 neutral scenes.

RESULTS

Across all patients, increased activation to disorder-related v. neutral scenes was found in subregions of the bilateral amygdala. In addition, activation of the lateral amygdala to disorder-related v. neutral scenes correlated positively with subjective anxiety ratings of scenes across patients. Furthermore, whole-brain analysis revealed increased responses to disorder-related threat across the four disorders in middle, medial and superior frontal regions, (para-)limbic regions, such as the insula and thalamus, as well as in the brainstem and occipital lobe. We found no disorder-specific brain responses.

CONCLUSIONS

The results suggest that pathologically heightened lateral amygdala activation is linked to experienced anxiety across anxiety disorders and trauma- and stressor-related disorders. Furthermore, the transdiagnostically shared activation network points to a common neural basis of abnormal responses to disorder-related threat stimuli across the four investigated disorders.

Brain responses to disorder-related visual threat in panic disorder

Panic disorder (PD) patients show aberrant neural responses to threatening stimuli in an extended fear network, but results are only partially comparable, and studies implementing disorder-related visual scenes are lacking as stimuli. The neural responses and functional connectivity to a newly developed set of disorder-related, ecologically valid scenes as compared with matched neutral visual scenes, using event-related functional magnetic resonance imaging (fMRI) in 26 PD patients and 26 healthy controls (HC) were investigated. PD patients versus HC showed hyperactivation in an extended fear network comprising brainstem, insula, thalamus, anterior, and mid-cingulate cortex and (dorso-)medial prefrontal cortex for disorder-related versus neutral scenes. Amygdala differences between groups failed significance. Subjective levels of anxiety significantly correlated with brainstem activation in PD patients. Analysis of functional connectivity by means of beta series correlation revealed no emotion-specific alterations in connectivity in PD patients versus HC. The results suggest that subjective anxiety evoked by external stimuli is directly related to altered activation in the homeostatic alarm system in PD. With novel disorder-related stimuli, the study sheds new light on the neural underpinnings of pathological threat processing in PD. Hum Brain Mapp 37:4439-4453, 2016. © 2016 Wiley Periodicals, Inc.

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.

The neuroanatomical basis of panic disorder and social phobia in schizophrenia: a voxel based morphometric study

Objective

It is known that there is a high prevalence of certain anxiety disorders among schizophrenic patients, especially panic disorder and social phobia. However, the neural underpinnings of the comorbidity of such anxiety disorders and schizophrenia remain unclear. Our study aims to determine the neuroanatomical basis of the co-occurrence of schizophrenia with panic disorder and social phobia.

Methods

Voxel-based morphometry was used in order to examine brain structure and to measure between-group differences, comparing magnetic resonance images of 20 anxious patients, 20 schizophrenic patients, 20 schizophrenic patients with comorbid anxiety, and 20 healthy control subjects.

Results

Compared to the schizophrenic patients, we observed smaller grey-matter volume (GMV) decreases in the dorsolateral prefrontal cortex and precentral gyrus in the schizophrenic-anxiety group. Additionally, the schizophrenic group showed significantly reduced GMV in the dorsolateral prefrontal cortex, precentral gyrus, orbitofrontal cortex, temporal gyrus and angular/inferior parietal gyrus when compared to the control group.

Conclusions

Our findings suggest that the comorbidity of schizophrenia with panic disorder and social phobia might be characterized by specific neuroanatomical and clinical alterations that may be related to maladaptive emotion regulation related to anxiety. Even thought our findings need to be replicated, our study suggests that the identification of neural abnormalities involved in anxiety, schizophrenia and schizophrenia-anxiety may lead to an improved diagnosis and management of these conditions.

Multiple white matter volume reductions in patients with panic disorder: relationships between orbitofrontal Gyrus volume and symptom severity and social dysfunction

Numerous brain regions are believed to be involved in the neuropathology of panic disorder (PD) including fronto-limbic regions, thalamus, brain stem, and cerebellum. However, while several previous studies have demonstrated volumetric gray matter reductions in these brain regions, there have been no studies evaluating volumetric white matter changes in the fiber bundles connecting these regions. In addition, although patients with PD typically exhibit social, interpersonal and occupational dysfunction, the neuropathologies underlying these dysfunctions remain unclear. A voxel-based morphometry study was conducted to evaluate differences in regional white matter volume between 40 patients with PD and 40 healthy control subjects (HC). Correlation analyses were performed between the regional white matter volumes and patients' scores on the Panic Disorder Severity Scale (PDSS) and the Global Assessment of Functioning (GAF). Patients with PD demonstrated significant volumetric reductions in widespread white matter regions including fronto-limbic, thalamo-cortical and cerebellar pathways (p<0.05, FDR corrected). Furthermore, there was a significant negative relationship between right orbitofrontal gyrus (OFG) white matter volume and the severity of patients' clinical symptoms, as assessed with the PDSS. A significant positive relationship was also observed between patients' right OFG volumes and their scores on the GAF. Our results suggest that volumetric reductions in widespread white matter regions may play an important role in the pathology of PD. In particular, our results suggest that structural white matter abnormalities in the right OFG may contribute to the social, personal and occupational dysfunction typically experienced by patients with PD.

Increased brain serotonin turnover in panic disorder patients in the absence of a panic attack: reduction by a selective serotonin reuptake inhibitor

Since the brain neurotransmitter changes characterising panic disorder remain uncertain, we quantified brain noradrenaline and serotonin turnover in patients with panic disorder, in the absence of a panic attack. Thirty-four untreated patients with panic disorder and 24 matched healthy volunteers were studied. A novel method utilising internal jugular venous sampling, with thermodilution measurement of jugular blood flow, was used to directly quantify brain monoamine turnover, by measuring the overflow of noradrenaline and serotonin metabolites from the brain. Radiographic depiction of brain venous sinuses allowed differential venous sampling from cortical and subcortical regions. The relation of brain serotonin turnover to serotonin transporter genotype and panic disorder severity were evaluated, and the influence of an SSRI drug, citalopram, on serotonin turnover investigated. Brain noradrenaline turnover in panic disorder patients was similar to that in healthy subjects. In contrast, brain serotonin turnover, estimated from jugular venous overflow of the metabolite, 5-hydroxyindole acetic acid, was increased approximately 4-fold in subcortical brain regions and in the cerebral cortex (P < 0.01). Serotonin turnover was highest in patients with the most severe disease, was unrelated to serotonin transporter genotype, and was reduced by citalopram (P < 0.01). Normal brain noradrenaline turnover in panic disorder patients argues against primary importance of the locus coeruleus in this condition. The marked increase in serotonin turnover, in the absence of a panic attack, possibly represents an important underlying neurotransmitter substrate for the disorder, although this point remains uncertain. Support for this interpretation comes from the direct relationship which existed between serotonin turnover and illness severity, and the finding that SSRI administration reduced serotonin turnover. Serotonin transporter genotyping suggested that increased whole brain serotonin turnover most likely derived not from impaired serotonin reuptake, but from increased firing in serotonergic midbrain raphe neurons projecting to both subcortical brain regions and the cerebral cortex.

Reduced gamma-aminobutyric acid(A)-benzodiazepine binding sites in insular cortex of individuals with panic disorder

CONTEXT

Benzodiazepine drugs are highly effective anxiolytic medications, but the role of the benzodiazepine-gamma-aminobutyric acid(A)-chloride ion channel macromolecular complex in the pathophysiologic mechanism of anxiety is not well understood. Previous human imaging studies have indicated involvement of specific regions of the brain in anxiety disorders, especially the frontal-prefrontal, temporal, and cingulate cortical and the limbic areas.

OBJECTIVE

To identify potential abnormalities of brain benzodiazepine receptor binding number and distribution in anxiety disorders.

SETTING AND PARTICIPANTS

At the University of Michigan positron emission tomography facility, 11 individuals with DSM-IV-defined anxiety syndrome panic disorder were compared with 21 unaffected healthy control subjects. Design and Main Outcome Measure In a between-group comparison, we used positron emission tomography and the benzodiazepine receptor ligand flumazenil labeled with carbon 11 to assess the regional brain pattern of receptor binding.

RESULTS

We observed decreased binding specifically in the insular cortex bilaterally. No binding abnormality was observed in any other brain region, and there was no evidence of abnormal cerebral blood flow anywhere in the brain. Individuals with panic disorder and comorbid depression, indicative of a more severe disorder, had the lowest binding. No significant correlations were observed for binding with age, sex, or duration of disorder.

CONCLUSIONS

A previous smaller study with the same ligand reported a probable binding abnormality in the right insula. Because gamma-aminobutyric acid is a major inhibitory neurotransmitter in the brain and because benzodiazepines facilitate this effect of gamma-aminobutyric acid, decreased benzodiazepine binding is consistent with localized brain activation (ie, loss of inhibition). Because the insula is strongly involved in visceral-somatic afferent and efferent function, activation of the insula is consistent with the occurrence of the physical symptoms prominently associated with panic disorder.

Changes in cerebral glucose utilization in patients with panic disorder treated with cognitive–behavioral therapy

Several neuroanatomical hypotheses of panic disorder have been proposed focusing on the significant role of the amygdala and PAG-related "panic neurocircuitry." Although cognitive-behavioral therapy is effective in patients with panic disorder, its therapeutic mechanism of action in the brain remains unclear. The present study was performed to investigate regional brain glucose metabolic changes associated with successful completion of cognitive-behavioral therapy in panic disorder patients. The regional glucose utilization in patients with panic disorder was compared before and after cognitive-behavioral therapy using positron emission tomography with (18)F-fluorodeoxyglucose. In 11 of 12 patients who showed improvement after cognitive-behavioral therapy, decreased glucose utilization was detected in the right hippocampus, left anterior cingulate, left cerebellum, and pons, whereas increased glucose utilization was seen in the bilateral medial prefrontal cortices. Significant correlations were found between the percent change relative to the pretreatment value of glucose utilization in the left medial prefrontal cortex and those of anxiety and agoraphobia-related subscale of the Panic Disorder Severity Scale, and between that of the midbrain and that of the number of panic attacks during the 4 weeks before each scan in all 12 patients. The completion of successful cognitive-behavioral therapy involved not only reduction of the baseline hyperactivity in several brain areas but also adaptive metabolic changes of the bilateral medial prefrontal cortices in panic disorder patients.

Decreased blood flow of temporal regions of the brain in subjects with panic disorder

OBJECT

The purpose of the current study was to investigate alterations of regional cerebral blood flow (rCBF) in subjects with panic disorder.

METHODS

Twenty-two subjects with panic disorder who were under psychotropic medications and 25 age and gender-matched healthy comparison subjects were assessed regarding the rCBF of using Tc-99m-hexamethyl propylenamino oxime single photon emission tomography (SPECT). Using statistical parametric mapping, the rCBF was compared between panic disorder and healthy comparison groups.

RESULTS

Decreased rCBF flow in right superior temporal lobe was observed in subjects with panic disorder (p<0.05 after correction for multiple comparisons). The rCBF in right superior temporal gyrus negatively correlated with the duration of illness, scores of panic disorder severity scale (PDSS), Hamilton anxiety rating scale (HARS) and Zung self-rating anxiety scale (Z-SAS).

CONCLUSION

We report that there is a decreased cerebral blood flow of temporal regions of the brain in panic disorder and that this decrease may, in part, reflect the clinical severity of panic disorder.

Brain serotonin1A receptor binding in major depression is related to psychic and somatic anxiety

BACKGROUND

The anxious phenotype of the 5-HT1A receptor knockout mouse and the anxiolytic properties of 5-HT1A agonists suggest that the 5-HT1A receptor modulates anxiety. We investigated the relationship of anxiety expressed in major depressive disorder (MDD) to regional 5-HT1A binding.

METHODS

Positron emission tomography with [carbonyl-11C]WAY-100635 was used to estimate regional 5-HT1A binding potential (BP) in 28 medication-free MDD subjects. Stepwise linear regression assessed the predictive capacity of three anxiety components, derived from a larger MDD sample and termed psychic, somatic, and motoric anxiety, on regional 5-HT1A BP.

RESULTS

Higher psychic (beta >or= .63) and lower somatic (beta <or= -.70) anxiety predicted over 50% of the variance in 5-HT1A BP in multiple cortical regions, but not in amygdala, hippocampus, or autoreceptors of the raphe nuclei. The psychic and somatic anxiety components were not related to depression severity. Comorbid panic disorder was associated with lower cortical and subcortical 5-HT1A BP.

CONCLUSIONS

The 5-HT1A receptor in the same brain regions has different relationships to psychic anxiety versus somatic anxiety. Lower 5-HT1A BP in panic disorder may be accounted for by higher somatic and lower psychic anxiety. Further study of the pathobiology of these anxiety components may identify distinct therapeutic targets or mechanisms.

Evaluation of cerebral blood flow volume using color duplex sonography in patients with untreated panic disorder

The aim of this study was to compare cerebral blood flow (CBF) using color duplex sonography in panic disorder and normal controls. We report 24 untreated patients and 20 healthy subjects. State-Trait Anxiety Inventory, Beck Depression Inventory, Beck Anxiety Inventory, and Symptom Check List-90 were completed on each subject. The internal carotid artery (ICA) and vertebral artery (VA) of both sides were explored with a 7.5-Mhz linear array transducer. CBF volume and mean ICA flow velocity were significantly higher in patients than normal subjects adjusted for age. However, we could not find a statistically significant difference in flow volume and velocity of VA and the sum of bilateral ICA volume between patients and controls adjusted for age. There was also no correlation between CBF volume and the other radiological data with STAI scores. In conclusion, we found that independent of anxiety levels, CBF volume has increased in panic disorder patients. In addition, color duplex sonography is a non-invasive and easily applicable technique and it is a preferable alternative to quantify CBF volume.

Prediction of panic response to a respiratory stimulant by reduced orbitofrontal cerebral blood flow in panic disorder

OBJECTIVE

Lack of appropriate top-down governance by frontal cortical regions over a hypersensitive amygdala-centered fear neurocircuitry has been hypothesized to be central in the pathophysiology of panic disorder. The aim of this study was to examine regional cerebral blood flow changes in response to anxiety/panic provocation in subjects with panic disorder and healthy comparison subjects.

METHOD

Quantitative water method positron emission tomography was used to obtain brain images of five untreated subjects with panic disorder and five healthy comparison subjects before and during anxiogenic challenge with intravenous doxapram, an acute respiratory stimulant.

RESULTS

Baseline perfusion of the orbitofrontal cortex predicted panic attacks: lower perfusion was associated with heightened anxiety in response to doxapram challenge.

CONCLUSIONS

The orbitofrontal cortex may be important in the regulation of responding to fear and is a potential area of aberrant functioning in panic disorder.

Cerebral glucose metabolism associated with a fear network in panic disorder

The present study was performed to assess cerebral glucose metabolism in patients with panic disorder using positron emission tomography. F-fluorodeoxyglucose positron emission tomography with voxel-based analysis was used to compare regional brain glucose utilization in 12 nonmedicated panic disorder patients, without their experiencing panic attacks during positron emission tomography acquisition, with that in 22 healthy controls. Panic disorder patients showed appreciably high state anxiety before scanning, and exhibited significantly higher levels of glucose uptake in the bilateral amygdala, hippocampus, and thalamus, and in the midbrain, caudal pons, medulla, and cerebellum than controls. These results provided the first functional neuroimaging support in human patients for the neuroanatomical hypothesis of panic disorder focusing on the amygdala-based fear network.

The change of regional brain metabolism (18FDG PET) in panic disorder during the treatment with cognitive behavioral therapy or antidepressants

BACKGROUND

The goal of our study was to identify brain structures in patients with panic disorder (PD) that show changes in 18FDG PET during the treatment with cognitive behavioral therapy (CBT) or antidepressants.

METHOD

Twelve patients suffering from panic disorder were studied with [18F]-2-fluoro-deoxyglucose positron emission tomography (18FDG PET) scanning during resting state (condition of random episodic silent thinking, REST). After PET examination patients were randomly assigned to either cognitive behavioral treatment group (6 patients) or antidepressants treatment group (6 patients). After a 3 month period 18FDG PET examination was repeated in both groups. Psychopathology was assessed using the rating scales HAMA, CGI and Panic Disorder Severity Scale (PDSS). Data were analysed using software for statistical parametric mapping (SPM99).

RESULTS

The scores of psychopathology rating scales (CGI, HAMA, PDSS) decreased in both groups. Changes of 18FDG uptake in the pharmacotherapy group: decreases were found in the a priori hypothesized regions in the right hemisphere, in the superior, middle, medial and inferior frontal gyrus, superior and middle temporal gyrus, and increases were detected in the a priori hypothesized regions, mainly in the left hemisphere in medial and middle frontal gyrus, superior, middle and transverse temporal gyrus. Changes of 18FDG uptake in the CBT group: decreases were found in the a priori hypothesized regions of the right hemisphere in the inferior temporal gyrus, superior and inferior frontal gyrus, and increases were detected in the a priori hypothesized region, mostly in the left hemisphere: inferior frontal gyrus, middle temporal gyrus and insula. We did not detect changes in 18FDG uptake in the limbic region (hippocampus, parahippocampal gyrus and amygdala).

CONCLUSIONS

Changes in brain metabolism (18FDG uptake) after the treatment either with CBT or with antidepressants were similar in number of brain areas, with prominent right-left difference. This is in concordance with the asymmetry of brain activity noted in patients with PD according to previous PET (and SPECT) studies.

123I-Metaiodobenzylguanidine myocardial scintigraphy in panic disorder

Although autonomic function has been investigated in panic disorder, previous studies have not yet revealed a consistent autonomic change in this disease. The purpose of this study was to evaluate the cardiac sympathetic function in panic disorder using (123)I-metaiodobenzylguanidine ((123)I-MIBG).

METHODS

Myocardial imaging using (123)I-MIBG was performed on 9 patients with panic disorder (7 men, 2 women; mean age, 37.4 +/- 13.2 y) and 11 control subjects (11 men; mean age, 37.6 +/- 9.3 y). Early (30 min) and delayed (4 h) planar images were taken after the injection of 111 MBq (123)I-MIBG. The mean counts in the whole heart and the mediastinum were obtained from the early and delayed images to calculate the heart-to-mediastinum count ratios (H/M ratios) and the myocardial washout rate.

RESULTS

The (123)I-MIBG H/M ratios of the patients with panic disorder were 1.80 +/- 0.16 for the early images and 1.86 +/- 0.30 for the delayed images, which were significantly lower than those of the control subjects (2.15 +/- 0.15 [P = 0.001] and 2.26 +/- 0.21 [P = 0.009], respectively). The (123)I-MIBG washout rate from the heart in the patients with panic disorder (33.8% +/- 6.9%) was significantly higher than that in the control subjects (27.8% +/- 3.5%) (P = 0.02).

CONCLUSION

(123)I-MIBG myocardial scintigraphy demonstrated impairment of cardiac sympathetic function in panic disorder. The results suggest that (123)I-MIBG imaging could become a useful tool for analyzing the pathophysiology of panic disorder.

Reduced serotonin type 1A receptor binding in panic disorder

Recent animal models suggest that disturbances in serotonin type-1A receptor (5-HT(1A)R) function may contribute to chronic anxiety, although it is not clear at all whether such models constitute relevant models for panic disorder (PD) in humans. The selective 5-HT(1A)R radioligand [18F]trans-4-fluoro-N-2-[4-(2-methoxyphenyl)piperazin-1-yl]ethyl]-N-(2-pyridyl)cyclohexanecarboxamide (FCWAY) permits in vivo assessment of central 5-HT(1A)R binding using positron emission tomography (PET). We studied 16 unmedicated symptomatic outpatients with PD and 15 matched healthy controls. Seven patients had an additional diagnosis of a current major depressive episode, however PD was the primary diagnosis. A 120 min PET study of 5-HT(1A)R binding was acquired using a GE Advance scanner in three-dimensional mode. Using quantitative PET image analysis, regional values were obtained for [18F]-FCWAY volume of distribution (DV), corrected for plasma protein binding, and K1, the delivery rate of [18F]-FCWAY from plasma to tissue. MRI scanning was performed using a GE Signa Scanner (3.0 Tesla) to provide an anatomical framework for image analysis and partial volume correction of PET data. PD patients showed lower DV in the anterior cingulate (t = 4.3; p < 0.001), posterior cingulate (t = 4.1; p < 0.001), and raphe (t = 3.1; p = 0.004). Comparing patients with PD, patients with PD and comorbid depression, and healthy controls revealed that DVs did not differ between PD patients and PD patients with comorbid depression, whereas both patient groups differed significantly from controls. These results provide for the first time in vivo evidence for the involvement of 5-HT(1A)Rs in the pathophysiology of PD.

Evaluation of regional cerebral blood flow changes in panic disorder with Tc99m-HMPAO SPECT

The objective of this study is to investigate differences in regional cerebral blood flow (rCBF) and rCBF asymmetry index values between panic disorder patients (n=22) and normal comparison subjects (n=19) using Tc99m-hexamethylpropyleneamine oxime single photon emission tomography imaging. A decrease in perfusion in the bilateral frontal regions and a relative increase in perfusion in the right medial and superior frontal regions were found. There were significant positive correlations between scores on the Panic and Agoraphobia Scale and rCBF asymmetry index values of the parietal, superior temporal and lateral temporal regions in the panic disorder patients. These correlations point to a relationship between the severity of panic disorder and relative right brain activation. Activation of the amygdala, increased CBF in the frontal region, or hyperactivation of the locus ceruleus seen in panic disorder may explain the decrease in the rCBF in the inferior frontal region.

Neuroimaging studies of amygdala function in anxiety disorders

Neuroimaging research has helped to advance neurobiological models of anxiety disorders. The amygdala is known to play an important role in normal fear conditioning and is implicated in the pathophysiology of anxiety disorders. The amygdala may also be a target for the beneficial effects of cognitive-behavioral and medication treatments for anxiety disorders. In the current paper, we review neuroimaging research pertaining to the role of the amygdala in anxiety disorders and their treatment. Moreover, we discuss the development of new neuroimaging paradigms for measuring aspects of amygdala function, as well as the function of related brain regions. We conclude that such tools hold great promise for facilitating progress in relevant basic neuroscience as well as clinical research domains.

Global cerebral blood flow after CO2 inhalation in normal subjects and patients with panic disorder determined with [15O]water and PET

OBJECTIVE

To determine the effect of CO2 inhalation on global cerebral blood flow (gCBF) and pCO2-adjusted gCBF in normal subjects and panic disorder patients.

METHOD

Global cerebral blood flow was determined using quantitative [15O] water imaging in normal subjects (n = 12) and panic disorder patients (n = 14) after inhalations of medical grade air and of 35%/65% CO2/O2 mixture, a known inducer of panic. The gCBF was calculated as an area-weighted mean value. The pCO2 -adjusted gCBF values were calculated based on the formula of Reiman et al. [Am. J. Psychiatr. 143 (1986) 469]. Data were analyzed using repeated-measures ANOVA and regression analyses.

RESULTS

The pCO2 values did not differ statistically between normals and panic patients. Panic patients exhibited a decrease in gCBF and stable pCO2-adjusted gCBF values in comparisons of AIR and CO2 inhalations, whereas normals exhibited stable gCBF and increasing pCO2-adjusted gCBF values.

CONCLUSIONS

Patients with panic disorder, especially when symptomatic, exhibited an abnormal pattern in gCBF response to provocation.

rCBF differences between panic disorder patients and control subjects during anticipatory anxiety and rest

BACKGROUND

Our goal was to identify brain structures involved in anticipatory anxiety in panic disorder (PD) patients compared to control subjects.

METHODS

Seventeen PD patients and 21 healthy control subjects were studied with H(2)(15)O positron emission tomography scan, before and after a pentagastrin challenge.

RESULTS

During anticipatory anxiety we found hypoactivity in the precentral gyrus, the inferior frontal gyrus, the right amygdala, and the anterior insula in PD patients compared to control subjects. Hyperactivity in patients compared to control subjects was observed in the parahippocampal gyrus, the superior temporal lobe, the hypothalamus, the anterior cingulate gyrus, and the midbrain. After the challenge, the patients showed decreases compared to the control subjects in the precentral gyrus, the inferior frontal gyrus, and the anterior insula. Regions of increased activity in the patients compared to the control subjects were the parahippocampal gyrus, the superior temporal lobe, the anterior cingulate gyrus, and the midbrain.

CONCLUSIONS

The pattern of regional cerebral blood flow activations and deactivations we observed both before and after the pentagastrin challenge was the same, although different in intensity. During anticipatory anxiety more voxels were (de)activated than during rest after the challenge.

Increased left posterior parietal-temporal cortex activation after D-fenfluramine in women with panic disorder

It is unclear whether the functional changes found in panic disorder reflect disturbed physiology of particular neurotransmitters. One method of investigating altered neurotransmission is to assess regional brain activations in response to agonist challenges. D-Fenfluramine is a medication that induces neuronal release of serotonin. Using ¿15OH(2)O and positron emission tomography (PET), measurements of regional cerebral blood flow (rCBF) were done at t=-20, -5, +20 and +35 relative to the IV D-fenfluramine injection (t=0) in nine panic-disordered and 18 healthy subjects. Subjects were otherwise healthy, right-handed, non-smoking and not taking psychotropic medication. ¿15OH(2)O PET scans were assessed with Statistical Parametric Mapping using individual global cerebral blood flow as a covariate. Comparisons of the (baseline) first two scans between healthy and panic-disordered subjects showed a decreased rCBF in the left posterior parietal-superior temporal cortex in the patient group. Fenfluramine-induced increases as defined by the last two scans minus the first two scans were compared between groups and a significantly greater increase in the same left posterior parietal-superior temporal region was found in panic-disordered subjects. Consistent with this finding, differences between the last two scans (post-fenfluramine) of the healthy and panic-disordered subjects showed an increased rCBF in the left superior temporal cortex in panic-disordered subjects. Functional pathology in the left parietal-superior temporal cortex in panic disorder may be related to abnormal modulation by serotonin.

SPECT [I-123]iomazenil measurement of the benzodiazepine receptor in panic disorder

BACKGROUND

Alterations in benzodiazepine receptor function have long been hypothesized to play a role in anxiety. Animal models of anxiety involving exposure to chronic stress have shown a specific decrease in benzodiazepine receptor binding in frontal cortex and hippocampus. The purpose of this study was to examine benzodiazepine receptor binding patients with panic disorder and comparison subjects.

METHODS

A quantitative measure related to benzodiazepine receptor binding (Distribution Volume (DV)) was obtained with single photon emission computed tomography (SPECT) imaging of [123I]iomazenil and measurement of radioligand concentration in plasma in patients with panic disorder and healthy controls. DV image data were analyzed using statistical parametric mapping (spm96).

RESULTS

A decrease in measures of benzodiazepine receptor binding (DV) was found in left hippocampus and precuneus in panic disorder patients relative to controls. Panic disorder patients who had a panic attack compared to patients who did not have a panic attack at the time of the scan had a decrease in benzodiazepine receptor binding in prefrontal cortex.

CONCLUSIONS

Findings of a decrease in left hippocampal and precuneus benzodiazepine receptor binding may be related to alterations in benzodiazepine receptor binding, or other factors including changes in GABAergic transmission or possible endogenous benzodiazepine compounds. Benzodiazepine receptor function in prefrontal cortex appears to be involved in changes in state-related panic anxiety.

[Benzodiazepine receptor imaging in the brain: recent developments and clinical validity]

Recent developments of benzodiazepine receptor imaging (123I-Iomazenil SPECT and 11C-Flumazenil PET) in neuropsychiatric disorders were reviewed. In focal epilepsy, a number of previous studies have reported a decreased benzodiazepine receptor binding in epileptic foci and greater sensitivity compared to regional cerebral blood flow imaging, especially for diagnosis of medial temporal lobe epilepsy. These findings indicate clinical validity of benzodiazepine receptor imaging in focal epilepsy and may be related to the "disinhibition mechanism" in GABA/benzodiazepine systems underlying epilepsy. In panic disorder, abnormal benzodiazepine receptor bindings are recently demonstrated in the temporal, parietal or frontal cortex. Further studies would clarify the "benzodiazepine dysfunction hypothesis" in panic disorder.

Regional cerebral metabolic asymmetries replicated in an independent group of patients with panic disorders

BACKGROUND

Abnormal left/right (L/R) hemispheric ratios of regional cerebral glucose metabolic rates (rCMRglc) (hippocampus and inferior prefrontal cortex) have been noted in unmedicated panic disorder patients.

METHODS

An independent group of panic disorder patients placed on imipramine was studied with positron-emission tomography, testing for evidence of normalization versus persistence of the abnormal rCMRglc ratios. Differences in orbital frontal rCMRglc values between the imipramine-treated and the previously reported unmedicated panic disorder patients were tested examining for evidence that the differences would resemble those noted in obsessive-compulsive disorder (OCD) patients treated with clomipramine.

RESULTS

We found the same abnormally low L/R hippocampal and posterior inferior prefrontal rCMRglc ratios in the imipramine-treated panic disorder patients. In addition, we found posterior orbital frontal rCMRglc decreases in the imipramine-treated panic disorder patients compared with the unmedicated panic disorder patients.

CONCLUSIONS

These abnormal asymmetries found in unmedicated panic disorder patients and now in imipramine-treated panic disorder patients may reflect a trait abnormality. The orbital frontal rCMRglc differences between the imipramine-treated and unmedicated patients are similar to changes noted in OCD patients treated with clomipramine and may reflect direct or indirect effects of imipramine treatment in panic disorder patients.

Cerebral glucose metabolism in women with panic disorder

OBJECTIVE

This study was undertaken to clarify earlier inconsistent findings in brain metabolic topography in panic disorder patients at rest.

METHOD

Positron emission tomography (PET) with [18F]fluorodeoxyglucose was used to determine cerebral metabolic activity in six female patients with a DSM-III-R diagnosis of panic disorder and in six healthy female volunteers. All patients with panic disorder were medication free and were sensitive to lactate infusion.

RESULTS

A significant increase in glucose metabolism was found in the left hippocampus and parahippocampal area of the panic disorder subjects in comparison with that found in the healthy subjects. In addition, a significant decrease in metabolism was found in the right inferior parietal and right superior temporal brain regions of the panic disorder subjects in comparison with that of the normal subjects. There was no significant correlation between scores for the severity of panic disorder or for the severity of lactate-induced panic attack and the quantified PET abnormality.

CONCLUSIONS

These data provide further support for the hypothesis of an abnormal brain metabolism in the hippocampal and parahippocampal area in individuals with panic disorder and also suggest other areas of aberrant brain metabolism in this disorder.

[Qualitative evaluation of brain structure in CT in panic disorders]

This CT study was designed to assess brain morphology in panic disorder with and without agoraphobia. Twenty-one patients and 21 normal control subjects matched for age and sex were investigated. Frontal and parieto-occipital cortex, temporal cortex, lateral ventricles and 3rd ventricle were evaluated by qualitative assessment on a 3-point scale (normal, questionable, abnormal). Patients showed significant bilateral enlargement of cortical cerebrospinal fluid (CSF) spaces (p < 0.01). The rating "abnormal" was given to none (0%) of the normal controls, but to 7 (33.3%) of the patients. Explorative analysis showed that these abnormalities were predominantly located in prefrontal regions. No qualitative differences were seen in the temporal cortex, lateral ventricles or third ventricle. These findings support the hypothesis that alterations in brain morphology are involved in the etiology of panic disorder. The lack of a correlation between CSF enlargement and duration of illness suggests that frontal CSF enlargement is a neurobiological vulnerability marker in panic disorder.

Decreased brain GABA(A)-benzodiazepine receptor binding in panic disorder: preliminary results from a quantitative PET study

BACKGROUND

Positron emission tomography (PET) allows the measurement of benzodiazepine-gamma-aminobutyric acidA (GABA(A)) receptor kinetics. We employed flumazenil radiolabeled with carbon 11, a radioligand that labels the benzodiazepine site on the GABA(A) receptor, and fully quantitative, high-sensitivity PET to test the hypothesis that central benzodiazepine site binding is decreased in medication-free patients with panic disorder.

METHODS

We compared 7 patients with panic disorder who had been off medication for at least 6 months and who had never abused alcohol with 8 healthy controls. The resulting parametric voxel-by-voxel maps were analyzed by voxel-based and region of interest-based methods using both parametric and nonparametric statistics.

RESULTS

The major finding was that there is a global reduction in benzodiazepine site binding throughout the brain in patients with panic disorder compared with controls. There were sex differences in the 2 samples, but a separate analysis excluding women led to the same conclusions. In addition, the loci with the largest regional decrease in binding (right orbitofrontal cortex and right insula) were areas thought to be essential in the central mediation of anxiety.

CONCLUSION

These results must be considered preliminary but are congruous with previous clinical psychopharmacologic evidence of involvement of the benzodiazepine-GABA(A) receptor and demonstrate that decreased flumazenil binding at this site may underlie panic disorder.

The application of positron emission tomography to the study of normal and pathologic emotions

This report reviews six studies in which positron emission tomography (PET) was used to investigate the neuroanatomic correlates of emotion, anxiety, and anxiety disorders. PET was used to study brain regions that participate in film- and recall-generated discrete emotions (happiness, sadness, and disgust), picture-generated positive and negative emotions, and normal anticipatory anxiety; participate in the predisposition to, elicitation of, and treatment of panic attacks; participate in social phobic anxiety; and participate in specific phobic anxiety. Results of these investigations suggest that thalamic and medial prefrontal regions may participate in aspects of normal emotion unrelated to its type, valence, or stimulus; that modality-specific sensory association areas and anterior temporal lobe regions appear to participate in the evaluation procedure that invests exteroceptive sensory information with emotional significance; that anterior insular regions appear to participate in the evaluation procedure that invests potentially distressing cognitive and interoceptive sensory information with negative emotional significance; and that anterior cingulate, cerebellar vermis, midbrain, and other brain regions appear to participate in the elaboration of normal and pathologic forms of anxiety. As a complement to other research strategies, PET promises to help determine how multiple brain regions and the mental operations to which they are related work in concert to produce emotions and how they conspire to produce emotional disorders.

Brain blood flow in anxiety disorders. OCD, panic disorder with agoraphobia, and post-traumatic stress disorder on 99mTcHMPAO single photon emission tomography (SPET)

BACKGROUND

We compared regional cerebral blood flow (rCBF) in three groups of patients with DSM-III-R anxiety disorders.

METHOD

Fifteen patients with obsessive -compulsive disorder (OCD), 15 with panic disorder with agoraphobia (PA), and 16 with post-traumatic stress disorder (PTSD) and a similar group of healthy controls were assessed on brain-dedicated high-resolution SPET.

RESULTS

MANOVA revealed significant rCBF differences between diagnostic groups (F = 4.4; d.f. = 3, 57; P = 0.007) and between cerebral regions (F = 6.4; d.f. = 1, 57; P = 0.01) in OCD and PTSD compared with PA and healthy controls, limited to bilateral superior frontal cortices and right caudate nuclei. Whole brain blood flow correlated positively with anxiety (r = 0.24, n = 46, P = 0.05). Beck depression scores correlated significantly negatively with left caudate rCBF (r = -0.24, n = 46, P = 0.05) and right caudate rCBF (r = -0.31, n = 46, P = 0.02). PTSD syndrome severity correlated significantly negatively with the left caudate (r = -0.49, n = 16, P = 0.03) and with right caudate rCBF (r = -0.7, n = 16, P = 0.001).

CONCLUSIONS

Functional rCBF differences in anxiety disorders could relate to repetitive, intrusive, distressing mental activity, prominent in both OCD and PTSD.