G. Van Wingen

Progesterone selectively increases amygdala reactivity in women

The acute neural effects of progesterone are mediated by its neuroactive metabolites allopregnanolone and pregnanolone. These neurosteroids potentiate the inhibitory actions of γ-aminobutyric acid (GABA). Progesterone is known to produce anxiolytic effects in animals, but recent animal studies suggest that pregnanolone increases anxiety after a period of low allopregnanolone concentration. This effect is potentially mediated by the amygdala and related to the negative mood symptoms in humans that are observed during increased allopregnanolone levels. Therefore, we investigated with functional magnetic resonance imaging (MRI) whether a single progesterone administration to healthy young women in their follicular phase modulates the amygdala response to salient, biologically relevant stimuli. The progesterone administration increased the plasma concentrations of progesterone and allopregnanolone to levels that are reached during the luteal phase and early pregnancy. The imaging results show that progesterone selectively increased amygdala reactivity. Furthermore, functional connectivity analyses indicate that progesterone modulated functional coupling of the amygdala with distant brain regions. These results reveal a neural mechanism by which progesterone may mediate adverse effects on anxiety and mood.

Gonadal hormone regulation of the emotion circuitry in humans

Gonadal hormones are known to influence the regulation of emotional responses and affective states. Whereas fluctuations in progesterone and estradiol are associated with increased vulnerability for mood disorders, testosterone is mainly associated with social dominance, aggressive, and antisocial behavior. Here, we review recent functional neuroimaging studies that have started to elucidate how these hormones modulate the neural circuitry that is important for emotion regulation, which includes the amygdala and the medial prefrontal (mPFC) and orbitofrontal cortex (OFC). The amygdala is thought to generate emotional responses, and the prefrontal brain regions to regulate those responses. Overall, studies that have investigated women during different phases of the menstrual cycle suggest that progesterone and estradiol may have opposing actions on the amygdala and prefrontal cortex. In addition, the influence of exogenous progesterone appears to be dose-dependent. Endogenous testosterone concentrations are generally positively correlated to amygdala and OFC responses, and exogenous testosterone increases amygdala reactivity. Whereas the administration of progesterone increases amygdala reactivity and its connectivity with the mPFC, testosterone administration increases amygdala reactivity but decreases its connectivity with the OFC. We propose that this opposing influence on amygdala-prefrontal coupling may contribute to the divergent effects of progesterone and testosterone on emotion regulation and behavioral inhibition, respectively, which may promote the differential vulnerability to various psychiatric disorders between women and men. This article is part of a Special Issue entitled: Neuroactive Steroids: Focus on Human Brain.

Perceived threat predicts the neural sequelae of combat stress.

Exposure to severe stressors increases the risk for psychiatric disorders in vulnerable individuals, but can lead to positive outcomes for others. However, it remains unknown how severe stress affects neural functioning in humans and what factors mediate individual differences in the neural sequelae of stress. The amygdala is a key brain region involved in threat detection and fear regulation, and previous animal studies have suggested that stress sensitizes amygdala responsivity and reduces its regulation by the prefrontal cortex. In this study, we used a prospective design to investigate the consequences of severe stress in soldiers before and after deployment to a combat zone. We found that combat stress increased amygdala and insula reactivity to biologically salient stimuli across the group of combat-exposed individuals. In contrast, its influence on amygdala coupling with the insula and dorsal anterior cingulate cortex was dependent on perceived threat, rather than actual exposure, suggesting that threat appraisal affects interoceptive awareness and amygdala regulation. Our results demonstrate that combat stress has sustained consequences on neural responsivity, and suggest a key role for the appraisal of threat on an amygdala-centered neural network in the aftermath of severe stress.

Paradoxical effects of GABA-A modulators may explain sex steroid induced negative mood symptoms in some persons

Some women have negative mood symptoms, caused by progestagens in hormonal contraceptives or sequential hormone therapy or by progesterone in the luteal phase of the menstrual cycle, which may be attributed to metabolites acting on the GABA-A receptor. The GABA system is the major inhibitory system in the adult CNS and most positive modulators of the GABA-A receptor (benzodiazepines, barbiturates, alcohol, GABA steroids), induce inhibitory (e.g. anesthetic, sedative, anticonvulsant, anxiolytic) effects. However, some individuals have adverse effects (seizures, increased pain, anxiety, irritability, aggression) upon exposure. Positive GABA-A receptor modulators induce strong paradoxical effects including negative mood in 3%-8% of those exposed, while up to 25% have moderate symptoms. The effect is biphasic: low concentrations induce an adverse anxiogenic effect while higher concentrations decrease this effect and show inhibitory, calming properties. The prevalence of premenstrual dysphoric disorder (PMDD) is also 3%-8% among women in fertile ages, and up to 25% have more moderate symptoms of premenstrual syndrome (PMS). Patients with PMDD have severe luteal phase-related symptoms and show changes in GABA-A receptor sensitivity and GABA concentrations. Findings suggest that negative mood symptoms in women with PMDD are caused by the paradoxical effect of allopregnanolone mediated via the GABA-A receptor, which may be explained by one or more of three hypotheses regarding the paradoxical effect of GABA steroids on behavior: (1) under certain conditions, such as puberty, the relative fraction of certain GABA-A receptor subtypes may be altered, and at those subtypes the GABA steroids may act as negative modulators in contrast to their usual role as positive modulators; (2) in certain brain areas of vulnerable women the transmembrane Cl(-) gradient may be altered by factors such as estrogens that favor excitability; (3) inhibition of inhibitory neurons may promote disinhibition, and hence excitability. This article is part of a Special Issue entitled: Neuroactive Steroids: Focus on Human Brain.

A functional MRI marker may predict the outcome of electroconvulsive therapy in severe and treatment-resistant depression

Electroconvulsive therapy (ECT) is effective even in treatment-resistant patients with major depression. Currently, there are no markers available that can assist in identifying those patients most likely to benefit from ECT. In the present study, we investigated whether resting-state network connectivity can predict treatment outcome for individual patients. We included forty-five patients with severe and treatment-resistant unipolar depression and collected functional magnetic resonance imaging scans before the course of ECT. We extracted resting-state networks and used multivariate pattern analysis to discover networks that predicted recovery from depression. Cross-validation revealed two resting-state networks with significant classification accuracy after correction for multiple comparisons. A network centered in the dorsomedial prefrontal cortex (including the dorsolateral prefrontal cortex, orbitofrontal cortex and posterior cingulate cortex) showed a sensitivity of 84% and specificity of 85%. Another network centered in the anterior cingulate cortex (including the dorsolateral prefrontal cortex, sensorimotor cortex, parahippocampal gyrus and midbrain) showed a sensitivity of 80% and a specificity of 75%. These preliminary results demonstrate that resting-state networks may predict treatment outcome for individual patients and suggest that resting-state networks have the potential to serve as prognostic neuroimaging biomarkers to guide personalized treatment decisions.

Allopregnanolone and mood disorders

UNLABELLED Certain women experience negative mood symptoms during the menstrual cycle and progesterone addition in estrogen treatments. In women with PMDD increased negative mood symptoms related to allopregnanolone increase during the luteal phase of ovulatory menstrual cycles. In anovulatory cycles no symptom or sex steroid increase occurs. This is unexpected as positive modulators of the GABA-A receptor are generally increasing mood. This paradoxical effect has brought forward a hypothesis that the symptoms are provoked by allopregnanolone the GABA-A receptor system. GABA-A is the major inhibitory system in the brain. Positive modulators of the GABA-A receptor include the progesterone metabolites allopregnanolone and pregnanolone, benzodiazepines, barbiturates, and alcohol. GABA-A receptor modulators are known, in low concentrations to induce adverse, anxiogenic effects whereas in higher concentrations show beneficial, calming properties. Positive GABA-A receptor modulators induce strong paradoxical effects e.g. negative mood in 3-8% of those exposed, while up to 25% have moderate symptoms thus similar as the prevalence of PMDD, 3-8% among women in fertile ages, and up to 25% have moderate symptoms of premenstrual syndrome (PMS). The mechanism behind paradoxical reaction might be similar among them who react on positive GABA-A receptor modulators and in women with PMDD. In women the severity of these mood symptoms are related to the allopregnanolone serum concentrations in an inverted U-shaped curve. Negative mood symptoms occur when the serum concentration of allopregnanolone is similar to endogenous luteal phase levels, while low and high concentrations have less effect on mood. Low to moderate progesterone/allopregnanolone concentrations in women increases the activity in the amygdala (measured with fMRI) similar to the changes seen during anxiety reactions. Higher concentrations give decreased amygdala activity similar as seen during benzodiazepine treatment with calming anxiolytic effects. Patients with PMDD show decreased sensitivity in GABA-A receptor sensitivity to diazepam and pregnanolone while increased sensitivity to allopregnanolone. This agrees with findings in animals showing a relation between changes in alpha4 and delta subunits of the GABA-A receptor and anxiogenic effects of allopregnanolone. CONCLUSION These findings suggest that negative mood symptoms in women with PMDD are caused by the paradoxical effect of allopregnanolone mediated via the GABA-A receptor.

The neural consequences of combat stress: long-term follow-up

Prolonged stress has long-lasting influences on neural functioning in rodents,1 but little is known about long-term influences of severe stress on the human brain. We previously reported that combat stress increased amygdala activity and that perceived threat during deployment predicted changes in amygdala connectivity from before to after deployment.2 To evaluate whether these changes endure over a longer period of time, we assessed amygdala functioning again, approximately 1.5 years after soldiers had returned from military deployment. The results show that in the absence of additional combat exposure, stress-induced amygdala hypersensitivity normalizes to the same level as before the combat, whereas perceived threat-dependent changes in amygdala coupling with the dorsal anterior cingulate cortex (dACC) persist.

Rhythmic finger tapping reveals cerebellar dysfunction in essential tremor

INTRODUCTION Cerebellar circuits are hypothesized to play a central role in the pathogenesis of essential tremor. Rhythmic finger tapping is known to strongly engage the cerebellar motor circuitry. We characterize cerebellar and, more specifically, dentate nucleus function, and neural correlates of cerebellar output in essential tremor during rhythmic finger tapping employing functional MRI. METHODS Thirty-one propranolol-sensitive essential tremor patients with upper limb tremor and 29 healthy controls were measured. T2*-weighted EPI sequences were acquired. The task consisted of alternating rest and finger tapping blocks. A whole-brain and region-of-interest analysis was performed, the latter focusing on the cerebellar cortex, dentate nucleus and inferior olive nucleus. Activations were also related to tremor severity. RESULTS In patients, dentate activation correlated positively with tremor severity as measured by the tremor rating scale part A. Patients had reduced activation in widespread cerebellar cortical regions, and additionally in the inferior olive nucleus, and parietal and frontal cortex, compared to controls. CONCLUSION The increase in dentate activation with tremor severity supports involvement of the dentate nucleus in essential tremor. Cortical and cerebellar changes during a motor timing task in essential tremor might point to widespread changes in cerebellar output in essential tremor.

The influence of stress on social cognition in patients with borderline personality disorder

BACKGROUND Borderline personality disorder (BPD) is characterized by severe difficulties in interpersonal relationships and emotional functioning. Theories of BPD suggest that individuals with BPD have heightened emotional sensitivity, increased stress reactivity, and problems in making sense of intentions of others. In this study we investigated stress reactivity in BPD and its interference with social cognition, and tested whether any differences are specific for BPD or are inherent to personality disorders in general. METHODS We investigated 22 patients with BPD, 23 patients with Cluster C personality disorder (CPD), and 24 nonpatients on facial emotion recognition and social evaluation before and after stress induction based on the Trier Social Stress Test (TSST). RESULTS The results show that stress increased subjective negative emotions in the BPD group to a larger extent than in the other groups, whereas physiological responses were attenuated. Importantly stress induction increased negative evaluations about others, but surprisingly to a similar extent in the BPD and CPD groups as in the nonpatient control group. In addition facial emotion recognition performance was higher after than before stress, but no significant group differences were observed. CONCLUSION These results suggest that heightened psychological reactivity in BPD co-occurs with attenuated physiological responses to psychosocial stress and that stress affects social cognition to a similar extent in BPD as in others.

Test-retest reliability of task-related pharmacological MRI with a single-dose oral citalopram challenge

Non-invasive assessment of human neurotransmitter function is a highly valuable tool in clinical research. Despite the current interest in task-based pharmacological MRI (phMRI) for the assessment of neural correlates of serotonin (5-HT) function, test-retest reliability of this technique has not yet been established. Using a placebo-controlled crossover design, we aimed to examine the repeatability of task-related phMRI with a single dose of oral citalopram in twelve healthy female subjects. Since we were interested in the drugs effect on neural correlates of 5-HT related cognitive processes, a sensorimotor and an emotional face processing paradigm were used. For both paradigms, we found no significant effects of the oral citalopram challenge on task-positive brain activity with whole-brain analysis. With ROI-based analysis, there was a small effect of the challenge related to emotional processing in the amygdala, but this effect could not be reproduced between sessions. We did however find reproducible effects of the challenge on task-negative BOLD-responses, particularly in the medial frontal cortex and paracingulate gyrus. In conclusion, our data shows that a single oral dose of citalopram does not reliably affect emotional processing and sensorimotor activity, but does influence task-negative processes in the frontal cortex. This latter finding validates previous studies indicating a role for 5-HT in suppression of the task-negative network during goal-directed behavior.