Abstract
Objective: Neurexan® is a medicinal product containing four diluted plant and mineral ingredients, passionflower, oats, coffee and zinc valerianate. It has been shown to reduce nervousness, restlessness, acute stress, and insomnia by modulating biological auto-regulating processes. Induced stress sensitizes the amygdala, which increases vigilance and in turn drives the stress response. This is mediated by an amygdala-prefrontal cortex (PFC) circuit, in which stress impairs the top-down cognitive functions of prefrontal regions, while strengthening the emotional bottom-up responses of the amygdala. We therefore hypothesized that Neurexan® may induce changes in amygdala activation during emotion processing elicited by an emotional expectancy task.
Methods: The drug effect was investigated in a randomized, placebocontrolled, double-blind, two-period-crossover clinical trial. The brain response of 37 male subjects (age range: 31–59) to the emotional expectancy paradigm was measured after intake of a single dose of Neurexan® or placebo by 3T functional magnetic resonance imaging. In the emotional expectancy task, negative, positive, and neutral IAPS pictures were presented, half of them preceded by visual cues. The visual cues before picture presentation were arrows pointing up (positive picture), down (negative picture) and to the right (neutral picture). The drug effect was assessed with paired t-test analysis comparing drug and placebo condition in the contrast expectancy positive [expectancy negative.
Results: We found amygdala activation in response to expected pictures, negative neutral, and positive. Furthermore, we observed significant differences in activation of the left amygdala during the expectancy task after the intake of Neurexan® as compared to the placebo condition. The differences in activation are explained by
reduced changes in amygdala reactivity modulated by Neurexan®.
Conclusion: The intake of a single dose of Neurexan® effects emotional processing represented by left amygdala activation and decreases amygdala reactivity during expectancy of emotional pictures.
