Baseline and acute changes in the HPA system in patients with anxiety disorders: the current state of research

Cannabidiol (CBD) potentiates physiological and behavioral markers of hypothalamic-pituitary-adrenal (HPA) axis responsivity in female and male mice

RATIONALE

Clinical literature indicates there may be a therapeutic use of cannabidiol (CBD) for stress-related disorders. Preclinical literature remains conflicted regarding the underlying neurobehavioral mechanisms, reporting mixed effects of CBD (increased, decreased, or no effect) on anxiety- and fear-related behaviors. Preclinical data demonstrated that CBD modulates hypothalamus-pituitary-adrenal (HPA) axis gene expression; it is unknown whether CBD changes HPA axis responsivity and how this relates to altered behavior.

OBJECTIVES

We aimed to evaluate whether acute or chronic CBD administration would alter physiological and behavioral measures of HPA axis responsivity in male or female mice.

METHODS

C57BL/6 mice of both sexes were injected with vehicle or CBD (30 mg/kg, i.p.) daily for 26 days. Plasma corticosterone (CORT) levels were evaluated following dexamethasone suppression and adrenocorticotropin hormone stimulation tests after acute and chronic CBD exposure. After chronic CBD, mice were tested for anxiety-like behavior using an elevated plus maze (EPM) and associative fear learning and memory using a trace fear conditioning (FC) protocol.

RESULTS

Compared to vehicle, CBD induced a state of HPA axis hyperactivation, an effect which was significant in males; it also normalized anxiety-like behavior in female mice classified as having HPA axis hypofunction and primed all female mice for enhanced conditioned responding. Significant sex differences were also detected: females had greater plasma CORT levels and HPA axis responsivity than males, exhibited less EPM anxiety-like behavior, and were more responsive during FC.

CONCLUSIONS

CBD potentiated physiological and behavioral markers of HPA axis function and normalized anxiety-like behavior in a sex-specific manner. This observation has implications for cannabinoid-based drug development targeting individuals with stress-related disorders involving HPA axis hypofunction pathology.

Dynamic Real-Time Biosensing Enabled Biorhythm Tracking for Psychiatric Disorders

This review article explores the transformative potential of dynamic, real-time biosensing in biorhythm tracking for psychiatric disorders. Psychiatric diseases, characterized by a complex, heterogeneous, and multifactorial pathophysiology, pose challenges in both diagnosis and treatment. Common denominators in the pathophysiology of psychiatric diseases include disruptions in the stress response, sleep-wake cycle, energy metabolism, and immune response: all of these are characterized by a strong biorhythmic regulation (e.g., circadian), leading to dynamic changes in the levels of biomarkers involved. Technological and practical limitations have hindered the analysis of such dynamic processes to date. The integration of biosensors marks a paradigm shift in psychiatric research. These advanced technologies enable multiplex, non-invasive, and near-continuous analysis of biorhythmic biomarkers in real time, overcoming the constraints of conventional approaches. Focusing on the regulation of the stress response, sleep/wake cycle, energy metabolism, and immune response, biosensing allows for a deeper understanding of the heterogeneous and multifactorial pathophysiology of psychiatric diseases. The potential applications of nanobiosensing in biorhythm tracking, however, extend beyond observation. Continuous monitoring of biomarkers can provide a foundation for personalized medicine in Psychiatry, and allow for the transition from syndromal diagnostic entities to pathophysiology-based psychiatric diagnoses. This evolution promises enhanced disease tracking, early relapse prediction, and tailored disease management and treatment strategies. As non-invasive biosensing continues to advance, its integration into biorhythm tracking holds promise not only to unravel the intricate etiology of psychiatric disorders but also for ushering in a new era of precision medicine, ultimately improving the outcomes and quality of life for individuals grappling with these challenging conditions.

Die soziale Angststörung – ein Update

Es kann passieren, dass man sich vermeintlich peinlich oder insuffizient verhält; kurzfristige Gefühle wie Scham oder Selbstzweifel bleiben meist jedoch ohne Bedeutung. Kommt es aber zu überzogenen und überdauernden Befürchtungen oder signifikantem Vermeidungsverhalten, kann es sich um eine soziale Angststörung (SAS) handeln. Der vorliegende Artikel bietet eine Übersicht über den aktuellen Stand der Ätiologie, Diagnostik und Therapie der SAS.

Clinical and neurobiological effects of aerobic exercise in dental phobia: A randomized controlled trial

BACKGROUND

Physical activity has shown to be effective in anxiety disorders. For specific phobia, no studies are available that systematically examined the effects of an aerobic exercise intervention on phobic fear within a randomized-controlled design. Therefore, we investigated the acute effect of a standardized aerobic training on clinical symptoms of dental phobia as well as on stress-related neurobiological markers.

METHODS

Within a crossover design, 30 patients with dental phobia (mean age: 34.1 years; mean score of the Dental Anxiety Scale: 18.8) underwent two minor dental interventions separated by 7 days. Dental treatment was performed after 30 min of physical activity at either 20% VO_{2 max} (control) or 70% VO_{2 max} (intervention), respectively. To control for habituation, patients were randomly assigned to one of the two conditions prior to the first intervention. Moreover, saliva samples were collected at five times in order to determine changes in salivary cortisol (sC) and alpha-amylase (sAA) due to treatment.

RESULTS

In comparison to baseline, aerobic exercise within 70% VO_{2 max} significantly reduced clinical anxiety and sC concentrations before, during, and after the dental treatment. In contrast, the control condition led to decreased sAA levels at different time points of measurement. Habituation occurred at the second study day, independent of the order.

CONCLUSIONS

Our study provides evidence for an effect of moderate-intense exercise on clinical symptoms and sC in patients with dental phobia. Therefore, acute aerobic exercise might be a simple and low-cost intervention to reduce disorder-specific phobic fear.

The psychology of HPA axis activation: Examining subjective emotional distress and control in a phobic fear exposure model

The HPA axis plays a key role in mediating the effects of "stress" on health, but clarifying mechanisms requires an understanding of psycho-biological linkages. There has long been an implicit assumption that subjective emotional distress (e.g., fear) should activate the HPA axis. Although this assumption was challenged 25 years ago (Curtis, 1976), laboratory studies in humans are limited. In this study we sought to replicate Curtis' findings and extend it by investigating if presence or absence of stressor control shapes HPA axis reactivity in a phobic fear exposure model. We recruited 19-45-year-old specific phobia participants (n=32 spider/snake phobia; n=14 claustrophobia) and gradually exposed them to their feared object or situation while measuring hormonal (ACTH and cortisol) and subjective (emotional distress, perceived control) responses. Utilizing a dyadic yoked design, we compared HPA reactivity when the pace of exposure was controlled by participants to identical exposure given to matched participants in the absence of control. Results showed that phobic fear exposure generated intense emotional distress without a corresponding increase in HPA axis activity. Although our actual manipulation of control failed to impact HPA responses, perceived control during exposure was associated with lower cortisol, an effect that was moderated by actual availability of stressor control. Our findings replicate Curtis' findings and challenge the still common but unsupported assumption that HPA axis activity reflects subjective distress. These results also highlight the importance of both perceived and actual aspects of stressor control in understanding what is truly "stressful" to the HPA axis system.

Effect of combined cognitive-behavioural therapy and endurance training on cortisol and salivary alpha-amylase in panic disorder

Current data point to an alteration of both the hypothalamo-pituitary-adrenal (HPA)-system and the peripheral transmission of catecholamines in anxiety disorders. There is also some evidence for the effect of several components of cognitive-behavioural interventions such as coping and control and for an effect of exercise training on the neuroendocrine stress response in healthy subjects as well as patients suffering from distinct (mental) disorders. This double-blind, controlled study investigated the effect of cognitive-behavioural therapy (CBT) in combination with either high-level endurance training or low-level exercise on salivary cortisol (sC) and on levels of salivary alpha-amylase (sAA) in patients suffering from panic disorder (PD) with and without agoraphobia. In comparison to the low-level exercise condition, there were significantly lower sC-levels in the experimental group performing high-level endurance training at a 7-month follow-up. In contrast, there were no group differences in sAA levels during the study period. In this trial, we found evidence for a decelerated effect of endurance-training on HPA-system's functioning in PD. Further studies addressing the alteration of sAA levels in this population might investigate physical exercise different in intensity and duration.