One milligram of lorazepam does not decrease anxiety induced by CCK-4 in healthy volunteers: investigation of neural correlates with BOLD MRI

Effect of BI 1358894 on Cholecystokinin-Tetrapeptide (CCK-4)-Induced Anxiety, Panic Symptoms, and Stress Biomarkers: A Phase I Randomized Trial in Healthy Males

INTRODUCTION

Depression, anxiety, and/or panic disorder are often comorbid and have a complex etiology mediated through the same neuronal network. Cholecystokinin-tetrapeptide (CCK-4), a synthetic analog of the endogenous neuropeptide cholecystokinin (CCK), is thought to be implicated in this network. The CCK-4 challenge model is an accepted method of investigating the pathophysiology of panic and has been shown to mediate neuronal activation via the transient receptor potential canonical (TRPC) ion channels.

OBJECTIVES

This study aimed to assess the pharmacodynamic effects of BI 1358894, a small-molecule inhibitor of TRPC ion channel members 4 and 5 (TRPC4/5), on CCK-4-induced anxiety/panic-like symptoms and evaluate circuit engagement.

METHODS

Twenty healthy male CCK-4-sensitive volunteers entered a Phase I, double blind, randomized, two-way cross-over, single dose, placebo-controlled trial. Randomization was to oral BI 1358894 100 mg in the fed state followed by oral placebo in the fed state, or vice versa. Treatments were administered 5 h prior to intravenous CCK-4 50 µg. The primary endpoint was maximum change from baseline of the Panic Symptom Scale (PSS) sum intensity score after CCK-4 injection. Further endpoints included the emotional faces visual analog score (EVAS), the Spielberger State-Trait Anxiety Inventory (STAI), plasma adrenocorticotropic hormone (ACTH), and serum cortisol values. The safety and tolerability of BI 1358894 was assessed based on a number of parameters including occurrence of adverse events (AEs). All pharmacodynamic, pharmacokinetic, and safety endpoints were analyzed using descriptive statistics.

RESULTS

Single oral doses of BI 1358894 were generally well tolerated by the healthy male volunteers included in this study. Adjusted mean maximum change from baseline in PSS sum intensity score was 24.4 % lower in volunteers treated with BI 1358894 versus placebo, while adjusted mean maximum change from baseline of EVAS was reduced by 19.2 % (BI 1358894 vs placebo). The STAI total score before CCK-4 injection was similar in both groups (placebo: 25.1; BI 1358894: 24.3). Relative to placebo, BI 1358894 reduced CCK-4-induced mean maximum plasma ACTH and serum cortisol values by 58.6 % and 27.3 %, respectively. Investigator-assessed drug-related AEs were reported for 13/20 participants (65.0 %). There were no serious or severe AEs, AEs of special interest, AEs leading to discontinuation of trial medication, or deaths.

CONCLUSIONS

Overall, BI 1358894 reduced psychological and physiological responses to CCK-4 compared with placebo, as measured by PSS, subjective EVAS and objectively measured stress biomarkers. BI 1358894 had a positive safety profile, and single oral doses were well tolerated by the healthy volunteers. This trial (NCT03904576/1402-0005) was registered on Clinicaltrials.gov on 05.04.19.

Specific and common functional connectivity deficits in drug-free generalized anxiety disorder and panic disorder: A data-driven analysis

Evidence of comparing neural network differences between anxiety disorder subtypes is limited, while it is crucial to reveal the pathogenesis of anxiety disorders. The present study aimed to investigate specific and common resting-state functional connectivity (FC) networks in generalized anxiety disorder (GAD), panic disorder (PD), and healthy controls (HC). We employed the gRAICAR algorithm to decompose the resting-state fMRI into independent components and align the components across 61 subjects (22 GAD, 18 PD and 21 HC). The default mode network and precuneus network exhibited GAD-specific aberrance, the anterior default mode network showed atypicality specific to PD, and the right fronto-parietal network showed aberrance common to GAD and PD. Between GAD-specific networks, FC between bilateral dorsolateral prefrontal cortex (DLPFC) was positively correlated with interoceptive sensitivity. In the common network, altered FCs between DLPFC and angular gyrus, and between orbitofrontal cortex and precuneus, were positively correlated with anxiety severity and interoceptive sensitivity. The pathological mechanism of PD could closely relate to the dysfunction of prefrontal cortex, while GAD could involve more extensive brain areas, which may be related to fear generalization.

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.

Benzodiazepines counteract rostral anterior cingulate cortex activation induced by cholecystokinin-tetrapeptide in humans

BACKGROUND

Benzodiazepines modulate γ-aminobutyric acid type A (GABA(A)) receptors throughout the brain. However, it is not fully understood which brain regions within anxiety-related brain circuits are really responsible for their anxiolytic effects and how these regions interact.

METHODS

We investigated whether the benzodiazepine alprazolam affects activity in distinct brain regions within anxiety-related circuits during an experimental anxiety paradigm by means of functional magnetic resonance imaging (fMRI). Panic symptoms were elicited by a bolus injection of the neuropeptide cholecystokinin-tetrapeptide (CCK-4) in 16 healthy male subjects in a double-blind, placebo-controlled design. Functional brain activation patterns were determined before and during the CCK-4-challenge without pretreatment and after treatment with either placebo or 1 mg alprazolam.

RESULTS

The CCK-4 induced anxiety and elicited widely distributed activation patterns in anxiety-related brain circuits, especially in the rostral anterior cingulate cortex (rACC), which was attenuated after alprazolam treatment. In contrast to placebo, alprazolam abolished the activation of the rACC after challenge with CCK-4 (p<.005, corrected for multiple comparisons) and increased functional connectivity between the rACC and other anxiety-related brain regions such as amygdala and prefrontal cortex. Moreover, the reduction in the CCK-4 induced activation of the rACC correlated with the anxiolytic effect of alprazolam (r(p) = .52; p = .04).

CONCLUSIONS

These findings put forward the rACC as a target for benzodiazepines and suggest that the CCK-4/fMRI paradigm might represent a human translational model for the investigation of anxiolytic drugs.

Amygdala responses to masked and low spatial frequency fearful faces: a preliminary fMRI study in panic disorder

Previous studies have demonstrated amygdala activation in response to fearful faces even if presented below the threshold of conscious visual perception. It has also been proposed that subcortical regions are selectively sensitive to low spatial frequency (LSF) information. However, chronic hyperarousal may reduce amygdala activation in panic disorder (PD). Our aim was to establish whether the amygdala is engaged by masked and LSF fearful faces in PD as compared to healthy subjects. Neutral faces were used as the mask stimulus. Thirteen PD patients (seven females, six males; mean age=29.1 (S.D: 5.9)) and 15 healthy volunteers (seven females, eight males; mean age=27.9 (S.D. 4.5)) underwent two passive viewing tasks during a 3T functional magnetic resonance imaging (fMRI) as follows: 1) presentation of faces with fearful versus neutral expressions (17ms) using a backward masking procedure and 2) presentation of the same faces whose spatial frequency contents had been manipulated by low-pass filtering. Level of awareness was confirmed by a forced choice fear-detection task. Whereas controls showed bilateral activation to fearful masked faces versus neutral faces, patients failed to show activation within the amygdala. LSF stimuli did not elicit amygdala response in either group, contrary to the view that LSF information plays a crucial role in the processing of facial expressions in the amygdala. Findings suggest maladaptive amygdala responses to potentially threatening visual stimuli in PD patients.

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.

Experimental panic provocation in healthy man-a translational role in anti-panic drug development?

Experimental neurochemical provocation of panic attacks in susceptible human subjects has considerably expanded our knowledge of the pathophysiology and psychopharmacology of panic disorder. Some panicogens also elicit short-lived panic-like states in healthy man. This offers the opportunity to assess the anti-panic action of drugs in proof-of-concept studies. However, from current data it is still unclear whether experimental panic in healthy man is a valid translational model. Most such studies in healthy volunteers have been performed using a cholecystokinin tetrapeptide (CCK-4) challenge. While CCK-4 panic was blocked by alprazolam pretreatment, escitalopram showed negative results in healthy man. Preliminary findings on novel investigational drugs and a few problematic results will be reviewed. Small sample sizes in many panic provocation studies, lack of dose-response aspects, and still-insufficient knowledge about the biological underpinning of experimental and spontaneous panic limit the interpretation of existing findings and should inspire further research.

Neuroimaging in anxiety disorders

Over the last few years, neuroimaging techniques have contributed greatly to the identification of the structural and functional neuroanatomy of anxiety disorders. The amygdala seems to be a crucial structure for fear and anxiety, and has consistently been found to be activated in anxiety-provoking situations. Apart from the amygdala, the insula and anterior cinguiate cortex seem to be critical, and all three have been referred to as the “fear network.” In the present article, we review the main findings from three major lines of research. First, we examine human models of anxiety disorders, including fear conditioning studies and investigations of experimentally induced panic attacks. Then we turn to research in patients with anxiety disorders and take a dose look at post-traumatic stress disorder and obsessive-compulsive disorder. Finally, we review neuroimaging studies investigating neural correlates of successful treatment of anxiety, focusing on exposure-based therapy and several pharmacological treatment options, as well as combinations of both.

Enhanced cue reactivity and fronto-striatal functional connectivity in cocaine use disorders

Chronic cocaine use is associated with enhanced cue reactivity to drug stimuli. However, it may also alter functional connectivity (fcMRI) in regions involved in processing drug stimuli. Our aims were to evaluate the neural regions involved in subjective craving and how fcMRI may be altered in chronic cocaine users. Fourteen patients with a confirmed diagnosis of cocaine abuse or dependence (CCA) and 16 gender, age, and education-matched healthy controls (HC) completed a cue reactivity task and a resting state scan while undergoing functional magnetic resonance imaging. CCA showed increased activation compared to HC in left dorsolateral prefrontal and bilateral occipital cortex in response to cocaine cues but not to appetitive control stimuli. Moreover, CCA also showed increased activation within the orbital frontal cortex (OFC) for cocaine cues relative to the appetitive stimuli during a hierarchical regression analysis. A negative association between subjective craving and activity in medial posterior cingulate gyrus (PCC) was also observed for CCA. CCA exhibited increased resting state correlation (positive) between cue-processing seed regions (OFC and ventral striatum), and negative connectivity between cue-processing regions and PCC/precuneus. These alterations in fcMRI may partially explain the neural basis of increased drug cue salience in CCA.