Atypical Anxiety-Related Amygdala Reactivity and Functional Connectivity in Sant Mat Meditation

Trait anxiety is related to Nx4's efficacy on stress-induced changes in amygdala-centered resting state functional connectivity: a placebo-controlled cross-over trial in mildly to moderately stressed healthy volunteers

BACKGROUND

The multicomponent drug Neurexan (Nx4) was shown to reduce the neural stress network activation. We now investigated its effects on stress-induced resting state functional connectivity (RSFC) in dependence of trait anxiety (TA), an acknowledged vulnerability factor for stress-induced psychopathologies.

METHODS

Nx4 was tested in a randomized placebo-controlled crossover trial. Resting state fMRI scans were performed before and after a psychosocial stress task and exploratively analyzed for amygdala centered RSFC. Effects of Nx4 on stress-induced RSFC changes were evaluated and correlated to TA levels. A subgroup analysis based on TA scores was performed.

RESULTS

Multiple linear regression analysis revealed a significant correlation between TA and Nx4 effect on stress-induced RSFC changes between right amygdala and pregenual anterior cingulate cortex (pgACC) and ventro-medial prefrontal cortex (vmPFC). For participants with above average TA, a significant amelioration of the stress-induced RSFC changes was observed.

CONCLUSIONS

The data add evidence to the hypothesis that Nx4's clinical efficacy is based on a dampened activation of the neural stress network, with a greater neural response in subjects with anxious personality traits. Further studies assessing clinically relevant outcome measures in parallel to fMRI are encouraged to evaluate the real-world benefit of Nx4. Trial registration NCT02602275.

Susceptibility of Women to Cardiovascular Disease and the Prevention Potential of Mind-Body Intervention by Changes in Neural Circuits and Cardiovascular Physiology

Women have been reported to be more vulnerable to the development, prognosis and mortality of cardiovascular diseases, yet the understanding of the underlying mechanisms and strategies to overcome them are still relatively undeveloped. Studies show that women's brains are more sensitive to factors affecting mental health such as depression and stress than men's brains. In women, poor mental health increases the risk of cardiovascular disease, and conversely, cardiovascular disease increases the incidence of mental illness such as depression. In connection with mental health and cardiovascular health, the presence of gender differences in brain activation, cortisol secretion, autonomic nervous system, vascular health and inflammatory response has been observed. This connection suggests that strategies to manage women's mental health can contribute to preventing cardiovascular disease. Mind-body interventions, such as meditation, yoga and qigong are forms of exercise that strive to actively manage both mind and body. They can provide beneficial effects on stress reduction and mental health. They are also seen as structurally and functionally changing the brain, as well as affecting cortisol secretion, blood pressure, heart rate variability, immune reactions and reducing menopausal symptoms, thus positively affecting women's cardiovascular health. In this review, we investigate the link between mental health, brain activation, HPA axis, autonomic nervous system, blood pressure and immune system associated with cardiovascular health in women and discuss the effects of mind-body intervention in modulating these factors.

Habitual physical activity mediates the acute exercise-induced modulation of anxiety-related amygdala functional connectivity

Aerobic exercise, in relation to physical activity, has been shown to have beneficial effects on anxiety. However, the underlyig neural mechanism remains elusive. Using a within-subject crossover design, this fMRI study examined how exercise (12-min treadmill running versus walking) mediated amygdala reactivity to explicit and implicit (backward masked) perception of emotional faces in young adults (N = 40). Results showed that acute exercise-induced differences of state anxiety (STAI-S) varied as a function of individual’s habitual physical activity (IPAQ). Subjects with high IPAQ levels showed significant STAI-S reduction (P < 0.05). Path analyses indicated that IPAQ explained 14.67% of the variance in acute exercise-induced STAI-S differences. Running elicited stronger amygdala reactivity to implicit happiness than fear, whereas walking did the opposite. The exercise-induced amygdala reactivity to explicit fear was associated with the IPAQ scores and STAI-S differences. Moreover, after running, the amygdala exhibited a positive functional connectivity with the orbitofrontal cortex and insula to implicit happiness, but a negative connectivity with the parahippocampus and subgenual cingulate to implicit fear. The findings suggest that habitual physical activity could mediate acute exercise-induced anxiolytic effects in regards to amygdala reactivity, and help establish exercise training as a form of anxiolytic therapy towards clinical applications.