The effect of a clinically effective and non-effective dose of lorazepam on 7.5% CO₂-induced anxiety

Biochemical challenges for testing novel anti-panic drugs in humans

Current medications for panic disorder each carry significant limitations that indicate the need for novel anxiolytics. The high costs and low success rates of drug development demand that testing trials be efficient. Lab panicogenic challenges in humans allow for the rapid biochemical induction of panic symptoms and hence an efficient means of testing potential anti-panic drugs. This paper describes ideal characteristics of lab panicogens, reviews the validity and utility of various biochemical panicogenic agents, identifies key outcome measures for studies of novel anti-panic drugs, and makes broad recommendations for labs wishing to perform such studies. We conclude by presenting a four-tiered hierarchy of panicogens that matches each against ideal characteristics and reflects our recommendations for their laboratory use.

Consensus on the pharmacological treatment of acute stress disorder in Chinese pilots: a Delphi study

BACKGROUND

Appropriate medication is very important for pilots with acute stress disorder. Improper medication can not only affect the physical and mental health of the pilots but can also endanger flight safety. Hence, we aimed to quickly and effectively relieve symptoms and restore cognitive function by forming a consensus of Chinese experts on the pharmacological treatment of acute stress disorder in pilots using the Delphi method.

METHODS

Relevant literature was searched to enumerate the current status of pharmacological treatment of acute stress disorder in pilots, followed by two rounds of expert consultation and discussion according to the listed status of the survey using the Delphi method. A descriptive statistical method was used to analyze the basic information, authority coefficients, concentration of opinions, and survey items of the experts to develop a consensus on the pharmacological treatment of acute stress disorder in pilots.

RESULTS

A total of 16 experts in psychiatry, pharmacology, and aerospace medicine from different provinces and cities across China were invited for consultation. The recovery rate of the two rounds of consultation was 100%, and the expert authority coefficients were 0.897 and 0.906, respectively. Kendall's coefficient of concordance of indicators at all levels was 0.564-0.594 (p < 0.01). Based on the number of votes received, alprazolam tablets (16), eszopiclone tablets (15), and lorazepam tablets (14) were recommended for the treatment of excitatory psychomotor symptoms of acute stress disorder; paroxetine tablets (15) and sertraline tablets (15) were available for psychomotor depressive symptoms; olanzapine tablets (15), olanzapine orally disintegrating tablets (14), and quetiapine fumarate tablets (14) were selected for psychotic symptoms.

CONCLUSIONS

This study formed a consensus on rapid and effective pharmacological treatment for different symptoms of acute stress disorder pilots, which provides a reference for clinical treatment.

The anti-anxiety drug lorazepam changes implicit behaviors but not explicit evaluations of sense of agency under authoritative pressure: A functional magnetic resonance imaging study

Previous research on coercion has neglected the fact that agents under authoritative pressure may also suffer from coercive power, which can trigger anxiety-like emotional negativity on its victims. Furthermore, high levels of neuroticism and/or anxiety have been found to be associated with the compliance of various forms of social pressure. In this study, we investigate the effects of the anxiolytic GABA A (gamma-Aminobutyric acid) modulator, lorazepam, on behavioral and neural responses to coercive power. Here, we applied a virtual obedience to authority paradigm alongside lorazepam administration (versus placebo), and during functional magnetic resonance imaging scanning. Our results show that lorazepam administration exerted differential effects on the reaction times (RTs) when initiating harming versus helping behaviors, with longer harming RTs compared to helping RTs, despite comparable subjective ratings regarding perceived coercion. Coercive harming significantly increased activity in the amygdala, hippocampus, orbitofrontal cortex, and dorsolateral prefrontal cortex (dlPFC). Lorazepam administration decreased amygdala and hippocampus activity, but increased dlPFC and right temporoparietal junction activations. The lower activity in the hippocampus predicted higher ratings for perceived coercion. Furthermore, lorazepam significantly decreased the functional connectivity of the hippocampus with the dlPFC during coercive harming. In conclusion, we provide evidence -by incorporating multimodal indices, including neuroimaging, neuropharmacological interventions, and behavioral assessments- to posit that the GABA A agonist, lorazepam, might aid as a possible intervention in service of coping strategies against coercion.

Experimentally induced and real-world anxiety have no demonstrable effect on goal-directed behaviour

BACKGROUND

Goal-directed control guides optimal decision-making and it is an important cognitive faculty that protects against developing habits. Previous studies have found some evidence of goal-directed deficits when healthy individuals are stressed, and in psychiatric conditions characterised by compulsive behaviours and anxiety. Here, we tested if goal-directed control is affected by state anxiety, which might explain the former results.

METHODS

We carried out a causal test of this hypothesis in two experiments (between-subject N = 88; within-subject N = 50) that used the inhalation of hypercapnic gas (7.5% CO2) to induce an acute state of anxiety in healthy volunteers. In a third experiment (N = 1413), we used a correlational design to test if real-life anxiety-provoking events (panic attacks, stressful events) are associated with impaired goal-directed control.

RESULTS

In the former two causal experiments, we induced a profoundly anxious state, both physiologically and psychologically, but this did not affect goal-directed performance. In the third, correlational, study, we found no evidence for an association between goal-directed control, panic attacks or stressful life eventsover and above variance accounted for by trait differences in compulsivity.

CONCLUSIONS

In sum, three complementary experiments found no evidence that anxiety impairs goal-directed control in human subjects.

Variation in the onset of CO2-induced anxiety in female Sprague Dawley rats

Carbon dioxide (CO₂) is commonly used to kill laboratory rats. Rats find CO₂ aversive and aversion varies between individuals, indicating that rats vary in CO₂ sensitivity. Healthy humans experience feelings of anxiety at concentrations similar to those avoided by rats, and these feelings are diminished by the administration of benzodiazepines. Our aim was to assess the effects of the benzodiazepine midazolam on individual thresholds of rat aversion to CO₂. Six female Sprague Dawley rats were repeatedly exposed to CO₂ gradual-fill in approach-avoidance testing. The first three exposures were to a control-treatment followed by three exposures to midazolam (0.375 mg/kg). Within each treatment aversion to CO₂ was not affected by exposure number; however, tolerance increased from an average of 10.7% CO₂ avoided during control sessions, to 15.5% CO₂ avoided when treated with midazolam. These results indicate that rats experience anxiety when exposed to CO₂, and that variation in rat CO₂ sensitivity is driven by individual differences in the onset of these feelings of anxiety. No rat tolerated CO₂ concentrations required to induce loss of consciousness.

Daily Ingestion of Eggplant Powder Improves Blood Pressure and Psychological State in Stressed Individuals: A Randomized Placebo-Controlled Study

Eggplant (Solanum melongena) is a globally popular vegetable and its significant health effect has not been reported in randomized controlled trials. Recently, we reported that eggplant was rich in choline esters, including acetylcholine (ACh), and had an antihypertensive effect in spontaneously hypertensive rats. Here, we evaluated the effects of a continuous intake of eggplant powder on blood pressure (BP), stress, and psychological state (PS) in 100 stressed participants with normal-high BP or grade 1 hypertension in a randomized, double-blind, placebo-controlled, parallel-group comparative study. The participants were randomly assigned to the eggplant or placebo group. Participants in the eggplant group ingested capsules containing eggplant powder (1.2 g/day; 2.3 mg of ACh/day) for 12 weeks, whereas participants in the placebo group ingested placebo capsules. The primary outcome assessed was hospital BP. Secondary outcomes were stress and PS. Eggplant powder intake significantly decreased the hospital diastolic blood pressure (DBP) at week 8 overall and in the normal-high BP group, and the systolic blood pressure (SBP) and DBP at week 12 overall and in the grade 1 hypertension group, compared to those of the placebo group. It also improved negative PSs at week 8 or 12 in the normal-high BP group. This is the first evidence of the BP- and PS-improving effects of eggplant intake in humans. The functional substance responsible for the effects was estimated to be eggplant-derived choline ester, namely ACh.

Pharmacotherapy in Generalized Anxiety Disorder: Novel Experimental Medicine Models and Emerging Drug Targets

Many pharmacological and psychological approaches have been found efficacious in patients with generalized anxiety disorder (GAD), but many treatment-seeking patients will not respond and others will relapse despite continuing with interventions that initially had beneficial effects. Other patients will respond but then stop treatment early because of untoward effects such as sexual dysfunction, drowsiness, and weight gain. There is much scope for the development of novel approaches that could have greater overall effectiveness or acceptability than currently available interventions or that have particular effectiveness in specific clinical subgroups. 'Experimental medicine' studies in healthy volunteers model disease states and represent a proof-of-concept approach for the development of novel therapeutic interventions: they determine whether to proceed to pivotal efficacy studies and so can reduce delays in translating innovations into clinical practice. Investigations in healthy volunteers challenged with the inhalation of air 'enriched' with 7.5% carbon dioxide (CO₂) indicate this technique provides a validated and robust experimental medicine model, mirroring the subjective, autonomic, and cognitive features of GAD. The anxiety response during CO₂ challenge probably involves both central noradrenergic neurotransmission and effects on acid-base sensitive receptors and so may stimulate development of novel agents targeted at central chemosensors. Increasing awareness of the potential role of altered cytokine balance in anxiety and the interplay of cytokines with monoaminergic mechanisms may also encourage the investigation of novel agents with modulating effects on immunological profiles. Although seemingly disparate, these two approaches to treatment development may pivot on a shared mechanism in exerting anxiolytic-like effects through pharmacological effects on acid-sensing ion channels.

Biological markers for anxiety disorders, OCD and PTSD: A consensus statement. Part II: Neurochemistry, neurophysiology and neurocognition

OBJECTIVE

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

METHODS

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

RESULTS

The present article (Part II) summarises findings on potential biomarkers in neurochemistry (neurotransmitters such as serotonin, norepinephrine, dopamine or GABA, neuropeptides such as cholecystokinin, neurokinins, atrial natriuretic peptide, or oxytocin, the HPA axis, neurotrophic factors such as NGF and BDNF, immunology and CO2 hypersensitivity), neurophysiology (EEG, heart rate variability) and neurocognition. The accompanying paper (Part I) focuses on neuroimaging and genetics.

CONCLUSIONS

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

Defensive eye-blink startle responses in a human experimental model of anxiety

Inhalation of low concentrations of carbon dioxide (CO2) triggers anxious behaviours in rodents via chemosensors in the amygdala, and increases anxiety, autonomic arousal and hypervigilance in healthy humans. However, it is not known whether CO2 inhalation modulates defensive behaviours coordinated by this network in humans. We examined the effect of 7.5% CO2 challenge on the defensive eye-blink startle response. A total of 27 healthy volunteers completed an affective startle task during inhalation of 7.5% CO2 and air. The magnitude and latency of startle eye-blinks were recorded whilst participants viewed aversive and neutral pictures. We found that 7.5% CO2 increased state anxiety and raised concurrent measures of skin conductance and heart rate (HR). CO2 challenge did not increase startle magnitude, but slowed the onset of startle eye-blinks. The effect of CO2 challenge on HR covaried with its effects on both subjective anxiety and startle latency. Our findings are discussed with reference to startle profiles during conditions of interoceptive threat, increased cognitive load and in populations characterised by anxiety, compared with acute fear and panic.