Left and right High Frequency repetitive Transcranial Magnetic Stimulation of the dorsolateral prefrontal cortex does not affect mood in female volunteers

Brain imaging studies of emotional well-being: a scoping review

This scoping review provides an overview of previous empirical studies that used brain imaging techniques to investigate the neural correlates of emotional well-being (EWB). We compiled evidence on this topic into one accessible and usable document as a foundation for future research into the relationship between EWB and the brain. PRISMA 2020 guidelines were followed. We located relevant articles by searching five electronic databases with 95 studies meeting our inclusion criteria. We explored EWB measures, brain imaging modalities, research designs, populations studied, and approaches that are currently in use to characterize and understand EWB across the literature. Of the key concepts related to EWB, the vast majority of studies investigated positive affect and life satisfaction, followed by sense of meaning, goal pursuit, and quality of life. The majority of studies used functional MRI, followed by EEG and event-related potential-based EEG to study the neural basis of EWB (predominantly experienced affect, affective perception, reward, and emotion regulation). It is notable that positive affect and life satisfaction have been studied significantly more often than the other three aspects of EWB (i.e., sense of meaning, goal pursuit, and quality of life). Our findings suggest that future studies should investigate EWB in more diverse samples, especially in children, individuals with clinical disorders, and individuals from various geographic locations. Future directions and theoretical implications are discussed, including the need for more longitudinal studies with ecologically valid measures that incorporate multi-level approaches allowing researchers to better investigate and evaluate the relationships among behavioral, environmental, and neural factors.

Systematic review registration

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Association between Mood and Sensation Seeking Following rTMS

Previous studies investigating mood changes in healthy subjects after prefrontal repetitive transcranial magnetic stimulation (rTMS) have shown largely inconsistent results. This may be due to methodological issues, considerable inter-individual variation in prefrontal connectivity or other factors, e.g., personality traits. This pilot study investigates whether mood changes after rTMS are affected by personality parameters. In a randomized cross-over design, 17 healthy volunteers received three sessions of 1 Hz rTMS to Fz, F3 and T3 (10/20 system). The T3 electrode site served as the control condition with the coil angled 45° to the scalp. Subjective mood was rated at baseline and after each condition. Personality traits were assessed using the NEO Five-Factor Inventory (NEO-FFI) and the Sensation Seeking Scale (SSS). For all conditions, a significant association between mood changes towards a deterioration in mood and SSS scores was observed. There were no differences between conditions and no correlations between mood changes and NEO-FFI. The data show that sensation-seeking personality has an impact on subjective mood changes following prefrontal rTMS in all conditions. Future studies investigating the effects of rTMS on emotional paradigms should include individual measures of sensation-seeking personality. The pre-selection of subjects according to personality criteria may reduce the variability in results.

Pre-frontal stimulation does not reliably increase reward responsiveness

Depression is the leading cause of disability worldwide and its effects can be fatal, with over 800,000 people dying by suicide each year. Neuromodulatory treatments such as transcranial magnetic stimulation (TMS) are being used to treat depression. Despite its endorsement by two regulatory bodies: NICE (2016) and the FDA (2008), there are major questions about the treatment efficacy and biological mechanisms of TMS. Ahn et al.'s (2013) justified the use of TMS in a clinical context in an important study indicating that excitatory TMS increases reward responsiveness. A pseudo-replication of this study by Duprat et al., (2016) also found a similar effect of active TMS, but only with the addition of an exploratory covariate to the analyses-trait reward responsiveness. Here we replicate Ahn et al.'s (2013) key study, and to test the reliability of the effects, and their dependency on trait reward responsiveness as described by Duprat et al., (2016). Using excitatory and sham TMS, we tested volunteers using the probabilistic learning task to measure their reward responsiveness both before and after stimulation. We also examined affect (positive, negative) following stimulation. Irrespective of TMS, the task was shown to be sensitive to reward responsiveness. However, we did not show TMS to be effective in increasing reward responsiveness and we did not replicate Ahn et al., (2013) or Duprat et al., (2016)'s key findings for TMS efficacy, where we provide evidence favouring the null. Moreover, exploratory analyses suggested following active stimulation, positive affect was reduced. Given our findings, we question the basic effects, which support the use of TMS for depression, particularly considering potential deleterious effects of reduced positive affect in patients with depression.

Effect of Intermittent Theta Burst Stimulation on the Neural Processing of Emotional Stimuli in Healthy Volunteers

BACKGROUND

Intermittent theta burst stimulation (iTBS) is a form of repetitive transcranial magnetic stimulation that has shown to be effective in treatment-resistant depression. Through studying the effect of iTBS on healthy subjects, we wished to attain a greater understanding of its impact on the brain. Our objective was to assess whether 10 iTBS sessions altered the neural processing of emotional stimuli, mood and brain anatomy in healthy subjects.

METHODS

In this double-blind randomized sham-controlled study, 30 subjects received either active iTBS treatment (10 sessions, two sessions a day) or sham treatment over the left dorsolateral prefrontal cortex. Assessments of mood, structural magnetic resonance imaging (MRI) and functional MRI (fMRI) were performed before and after iTBS sessions. During the fMRI, three different categories of stimuli were presented: positive, negative and neutral photographs.

RESULTS

This study showed that, during the presentation of negative stimuli (compared with neutral stimuli), 10 sessions of iTBS increased activity in the left anterior insula. However, iTBS did not induce any change in mood, regional gray matter volume or cortical thickness.

CONCLUSIONS

iTBS modifies healthy subjects' brain activity in a key region that processes emotional stimuli. (AFSSAPS: ID-RCB 2010A01032-37).

A Systematic Review of the Effectiveness of Non-Invasive Brain Stimulation Techniques to Reduce Violence Proneness by Interfering in Anger and Irritability

The field of neurocriminology has proposed several treatments (e.g., pharmacological, brain surgery, androgen-deprivation therapy, neurofeedback) to reduce violence proneness, but unfortunately, their effectiveness has been limited due to their side-effects. Therefore, it is necessary to explore alternative techniques to improve patients’ behavioural regulation with minimal undesirable effects. In this regard, non-invasive brain stimulation techniques, which are based on applying changing magnetic fields or electric currents to interfere with cortical excitability, have revealed their usefulness in alleviating the symptomatology of several mental disorders. However, to our knowledge, there are no reviews that assess whether these techniques are useful for reducing violence proneness. Therefore, we conducted a systematic review following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria using the following databases: PsycINFO, PubMed, Dialnet, Psicodoc, Web of Knowledge, and the Cochrane Library. We initially identified 3746 entries, and eventually included 56 publications. Most of the studies were unanimous in concluding that the application of these techniques over the prefrontal cortex (PFC) was not sufficient to promote anger and irritability reductions in euthymic individuals of both genders. Nevertheless, the application of non-invasive brain stimulation techniques, especially transcranial direct current stimulation, over the right PFC seemed to reduce violent reactions in these individuals by interfering with the interpretation of the unfavourable situations (e.g., threating signals) or inner states that evoked anger. In antisocial and pathological populations, the conclusions were provided by a few pilot studies with important methodological weaknesses. The main conclusion of these studies was that bilateral stimulation of the PFC satisfactorily reduced anger and irritability only in inmates, patients with autism spectrum disorders (ASD), people who suffered a closed-head injury, and agitated patients with Alzheimer’s disease. Moreover, combining these techniques with risperidone considerably reduced aggressiveness in these patients. Therefore, it is necessary to be cautious about the benefits of these techniques to control anger, due the methodological weaknesses of these studies. Nonetheless, they offer valuable opportunities to prevent violence by designing new treatments combining brain stimulation with current strategies, such as psychotherapy and psychopharmacology, in order to promote lasting changes.

Repetitive transcranial magnetic stimulation modulates the impact of a negative mood induction

High frequency repetitive Transcranial Magnetic Stimulation (rTMS) over the left dorsolateral prefrontal cortex (DLPFC) has been found to alleviate depressive symptoms. However, the mechanisms driving these effects are still poorly understood. In the current study, we tested the idea that this intervention protects against negative mood shifts following emotional provocation. We furthermore explored changes in EEG activity (frontal alpha asymmetry) and effects on attentional processing (emotional Stroop). To this end, 23 healthy individuals participated in two sessions separated by one week, whereby they once received 15 min of 10Hz rTMS stimulation (1500 pulses) at 110% of the individual motor threshold, and once sham stimulation. Then, negative mood was induced using sad movie clips. The results revealed a significantly stronger mood decline following rTMS compared to sham stimulation. No changes were observed in frontal alpha asymmetry and attentional processing. Our findings are at odds with the view that high frequency rTMS over the left DLPFC directly protects against the induction of negative mood, but rather suggest that it enhances the effects of emotional provocation. Possibly, in healthy young individuals, this stimulation protocol heightens susceptibility to mood induction procedures in general.

Effects of tDCS over the right DLPFC on attentional disengagement from positive and negative faces: An eye-tracking study

The aim of this study was to increase insight in the neural substrates of attention processes involved in emotion regulation. The effects of right dorsolateral prefrontal cortex (i.e., DLPFC) stimulation on attentional processing of emotional information were evaluated. A novel attention task allowing a straightforward measurement of attentional engagement toward, and attentional disengagement away from emotional faces was used. A sample of healthy participants received 20 minutes of active and sham anodal transcranial direct current stimulation (i.e., tDCS) applied over the right DLPFC on 2 separate days and completed the attention task after receiving real or sham stimulation. Compared to sham stimulation, tDCS over the right DLPFC led to impairments in attentional disengagement from both positive and negative faces. Findings demonstrate a causal role of right DLPFC activity in the generation of attentional impairments that are implicated in emotional disturbances such as depression and anxiety.

Affective Processing in Non-invasive Brain Stimulation Over Prefrontal Cortex

The prefrontal cortex (PFC) is the most frequently targeted brain region by non-invasive brain stimulation (NBS) studies. Non-invasively stimulating the PFC has been shown to both modulate affective processing and improve the clinical symptoms of several psychiatric disorders, such as depression and schizophrenia. The magnitude of the modulation depends on several factors, including the stimulation frequency, the number of stimulation sessions, and the specific sub-region of the PFC that is stimulated. Although some of the potential underlying mechanisms have been identified, the exact mechanisms that underlie these cognitive and affective changes remain unclear. The present review aims to summarize recent advances in the study of affective processing using NBS over the PFC. We will provide a theoretical framework for better understanding how affective processing changes are induced by NBS, with the goal of providing testable hypotheses for future studies.

Effect of repetitive transcranial magnetic stimulation on mood in healthy subjects

Background

High frequency repetitive transcranial magnetic stimulation (rTMS) of the left dorsolateral prefrontal cortex (DLPFC) has shown significant efficiency in the treatment of resistant depression. However in healthy subjects, the effects of rTMS remain unclear.

Objective

Our aim was to determine the impact of 10 sessions of rTMS applied to the DLPFC on mood and emotion recognition in healthy subjects.

Design

In a randomised double-blind study, 20 subjects received 10 daily sessions of active (10 Hz frequency) or sham rTMS. The TMS coil was positioned on the left DLPFC through neuronavigation. Several dimensions of mood and emotion processing were assessed at baseline and after rTMS with clinical scales, visual analogue scales (VASs), and the Ekman 60 faces test.

Results

The 10 rTMS sessions targeting the DLPFC were well tolerated. No significant difference was found between the active group and the control group for clinical scales and the Ekman 60 faces test. Compared to the control group, the active rTMS group presented a significant improvement in their adaptation to daily life, which was assessed through VAS.

Conclusion

This study did not show any deleterious effect on mood and emotion recognition of 10 sessions of rTMS applied on the DLPFC in healthy subjects. This study also suggested a positive effect of rTMS on quality of life.

Does non-invasive brain stimulation applied over the dorsolateral prefrontal cortex non-specifically influence mood and emotional processing in healthy individuals?

The dorsolateral prefrontal cortex (DLPFC) is often targeted with non-invasive brain stimulation (NIBS) to modulate in vivo human behaviors. This brain region plays a key role in mood, emotional processing, and attentional processing of emotional information. In this article, we ask the question: when we target the DLPFC with NIBS, do we modulate these processes altogether, non-specifically, or can we modulate them selectively? We thus review articles investigating the effects of NIBS applied over the DLPFC on mood, emotional processing, and attentional processing of emotional stimuli in healthy subjects. We discuss that NIBS over the DLPFC can modulate emotional processing and attentional processing of emotional stimuli, without specifically influencing mood. Indeed, there seems to be a lack of evidence that NIBS over the DLPFC influences mood in healthy individuals. Finally, there appears to be a hemispheric lateralization: when applied over the left DLPFC, NIBS improved processing of positive stimuli and reduced selective attention for stimuli expressing anger, whereas when applied over the right DLPFC, it increased selective attention for stimuli expressing anger.

[Experimental and therapeutic neuromodulation of emotion and social cognition with non-invasive brain stimulation]

Transcranial magnetic stimulation (TMS) is not only a highly elegant method for basic neuroscientific research that employs transient lesions to explore the relationship between brain structure and function but in a clinical context it is also a very promising approach to augmentation therapy in middle to severe grade depressive episodes. This overview illustrates the methodological basis of TMS and illuminates its neuromodulatory potential with reference to findings from recent studies on emotion regulation and social cognition. Against this empirical background, it becomes clear that preclinical studies on healthy participants are extremely important to develop innovative stimulation protocols and define functionally relevant target regions to be tested in clinical studies for therapeutic efficacy. Finally, the perspectives and limitations of functionally guided, individualized TMS neuronavigation will be explored based on task-independent connectivity and task-dependent activity measurements.

Diminished appetitive startle modulation following targeted inhibition of prefrontal cortex

From an evolutionary perspective the startle eye-blink response forms an integral part of the human avoidance behavioral repertoire and is typically diminished by pleasant emotional states. In major depressive disorder (MDD) appetitive motivation is impaired, evident in a reduced interference of positive emotion with the startle response. Given the pivotal role of frontostriatal neurocircuitry in orchestrating appetitive motivation, we hypothesized that inhibitory transcranial magnetic stimulation (TMS) would reduce appetitive neuromodulation in a manner similar to MDD. Based on a pre-TMS functional MRI (fMRI) experiment we selected the left dorsolateral and dorsomedial prefrontal cortices as target regions for subsequent sham-controlled inhibitory theta-burst TMS (TBS) in 40 healthy male volunteers. Consistent with our hypothesis, between-group comparisons revealed a TBS-induced inhibition of appetitive neuromodulation, manifest in a diminished startle response suppression by hedonic stimuli. Collectively, our results suggest that functional integrity of left dorsolateral and dorsomedial prefrontal cortex is critical for mediating a pleasure-induced down-regulation of avoidance responses which may protect the brain from a depressogenic preponderance of defensive stress.

tDCS over the left prefrontal cortex enhances cognitive control for positive affective stimuli

Transcranial Direct Current Stimulation (tDCS) is a neuromodulation technique with promising results for enhancing cognitive information processes. So far, however, research has mainly focused on the effects of tDCS on cognitive control operations for non-emotional material. Therefore, our aim was to investigate the effects on cognitive control considering negative versus positive material. For this sham-controlled, within-subjects study, we selected a homogeneous sample of twenty-five healthy participants. By using behavioral measures and event related potentials (ERP) as indexes, we aimed to investigate whether a single session of anodal tDCS of the left dorsolateral prefrontal cortex (DLPFC) would have specific effects in enhancing cognitive control for positive and negative valenced stimuli. After tDCS over the left DLPFC (and not sham control stimulation), we observed more negative N450 amplitudes along with faster reaction times when inhibiting a habitual response to happy compared to sad facial expressions. Gender did not influence the effects of tDCS on cognitive control for emotional information. In line with the Valence Theory of side-lateralized activity, this stimulation protocol might have led to a left dominant (relative to right) prefrontal cortical activity, resulting in augmented cognitive control specifically for positive relative to negative stimuli. To verify that tDCS induces effects that are in line with all aspects of the well known Valence Theory, future research should investigate the effects of tDCS over the left vs. right DLPFC on cognitive control for emotional information.

Translational application of neuromodulation of decision-making

Recent cognitive neuroscience studies indicate that noninvasive brain stimulation can modulate a wide spectrum of behaviors in healthy individuals. Such modulation of behaviors provides novel insights into the fundamentals and neurobiology of cognitive functions in the healthy brain, but also suggests promising prospects for translational applications into clinical populations. One type of behavior that can be modulated with noninvasive brain stimulation is decision-making. For instance, brain stimulation can induce more cautious or riskier behaviors. The capacity of influencing processes involved in decision-making is of particular interest because such processes are at the core of human social and emotional functioning (or dysfunctioning). We review cognitive neuroscience studies that have successfully modulated processes involved in decision-making with transcranial direct current stimulation (tDCS) or transcranial magnetic stimulation (TMS), including risk taking, reward seeking, impulsivity, and fairness consideration. We also discuss potential clinical relevance of these findings for patients who have still unmet therapeutic need and whose alterations in decision-making represent hallmarks of their clinical symptomatology, such as individuals with addictive disorders.

Transcranial pulsed magnetic field stimulation facilitates reorganization of abnormal neural circuits and corrects behavioral deficits without disrupting normal connectivity

Although the organization of neuronal circuitry is shaped by activity patterns, the capacity to modify and/or optimize the structure and function of whole projection pathways using external stimuli is poorly defined. We investigate whether neuronal activity induced by pulsed magnetic fields (PMFs) alters brain structure and function. We delivered low-intensity PMFs to the posterior cranium of awake, unrestrained mice (wild-type and ephrin-A2A5(-/-)) that have disorganized retinocollicular circuitry and associated visuomotor deficits. Control groups of each genotype received sham stimulation. Following daily stimulation for 14 d, we measured biochemical, structural (anterograde tracing), and functional (electrophysiology and behavior) changes in the retinocollicular projection. PMFs induced BDNF, GABA, and nNOS expression in the superior colliculus and retina of wild-type and ephrin-A2A5(-/-) mice. Furthermore, in ephrin-A2A5(-/-) mice, PMFs corrected abnormal neuronal responses and selectively removed inaccurate ectopic axon terminals to improve structural and functional organization of their retinocollicular projection and restore normal visual tracking behavior. In contrast, PMFs did not alter the structure or function of the normal projection in wild-type mice. Sham PMF stimulation had no effect on any mice. Thus, PMF-induced biochemical changes are congruent with its capacity to facilitate beneficial reorganization of abnormal neural circuits without disrupting normal connectivity and function.

Repetitive transcranial magnetic stimulation influences mood in healthy male volunteers

The influence of repetitive transcranial magnetic stimulation (rTMS) on mood in healthy people is uncertain, as former studies show divergent results. Previous studies in healthy volunteers focused exclusively on the immediate effect of a single session of rTMS. In contrast the aim of this randomised sham-controlled study was to analyse the influence on mood of a series of 9 High Frequency (HF) rTMS stimulations of the left dorsolateral prefrontal cortex (DLPFC). 44 young healthy male volunteers were randomly assigned to receive 9 sessions of active HF-rTMS (n = 22) or sham rTMS (n = 22) over the left DLPFC. Each session in the active group consisted of 15 trains of 25 Hz starting with 100% of motor threshold. Sham stimulation was performed following the same protocol, but using a sham coil. The variables of interest were the Beck Depression Inventory (BDI) and six Visual Analogue Scales (VAS) which quantified "mood", "enjoyment" and "energy". We found a significant reduction of the BDI sum score in the active group (GLM, p < 0.001) whereas no significant changes of the BDI sum score were caused by sham stimulation (GLM, p = 0.109). The BDI single item analyses revealed within and between group differences supporting the modifying effect of rTMS on BDI. According to the employed VAS we did not find significant differences caused by active or sham stimulation in five of six VAS. In the VAS labelled lively/gloomy the active group was found to be more "gloomy" (p = 0.0111) immediately after stimulation. Our data show that a 9-day long series of HF-rTMS of the left DLPFC improves mood, analysed by BDI in healthy young men, whereas no significant long-term changes were found in VAS.

The effect of one left-sided dorsolateral prefrontal sham-controlled HF-rTMS session on approach and withdrawal related emotional neuronal processes

OBJECTIVE

Although repetitive Transcranial Magnetic Stimulation (rTMS) is frequently used to examine emotional changes in healthy volunteers, it remains largely unknown how rTMS is able to influence emotion.

METHODS

In this sham-controlled, single-blind crossover study using fMRI, we examined in 20 right-handed healthy females whether a single high frequency (HF)-rTMS session applied to the left dorsolateral prefrontal cortex could influence emotional processing while focussing on blocks of positively and negatively valenced baby faces.

RESULTS

While positive information was being processed, we observed after one active HF-rTMS session enhanced neuronal activity in the left superior frontal cortex and right inferior parietal cortex. After sham HF-rTMS, we found significant decreases in neuronal activity in the left superior frontal cortex, the left inferior prefrontal cortex, as well as in the right posterior cingulate gyrus. When negative information was processed, one active stimulation attenuated neuronal activity in the right insula only.

CONCLUSIONS

Our findings suggest that during the processing of positive information one active session enhanced the ability to empathize with the depicted emotional stimuli, while during the processing of negative information it resulted in decreased psychophysiological reactions.

SIGNIFICANCE

These results provide new information on the working mechanism of left-sided HF-rTMS.

Baseline 'state anxiety' influences HPA-axis sensitivity to one sham-controlled HF-rTMS session applied to the right dorsolateral prefrontal cortex

Although negative results have been reported, an important aspect of the physiology of repetitive transcranial magnetic stimulation (rTMS) could be related to the endocrinological response of the hypothalamic-pituitary-adrenal (HPA) axis, such as cortisol secretion. Because endocrinological responses are influenced by anxiety states, this could influence the effect of rTMS in healthy individuals. In this sham-controlled, "single blind" crossover study, we examined whether one session of HF-rTMS could affect the HPA-system, when taking into account individual state anxiety scores based on the State-Trait Anxiety Inventory (STAI). Twenty-four healthy rTMS naïve females received one sham-controlled high frequency (HF)-rTMS session delivered on the right dorsolateral prefrontal cortex (DLPFC). The Profile of Mood States (POMS) questionnaire, together with salivary cortisol samples, was collected before, just after and 30 min post HF-rTMS. To examine whether state anxiety could influence endocrinological outcome measurements, we administered the STAI-state just before each HF-rTMS experiment started. Based on the POMS questionnaire, no mood changes were observed. Without taking individual state anxiety scores into account, one sham-controlled right-sided HF-rTMS session did not influence the HPA-system. When taking into account individual STAI-state scores, we found that healthy women scoring higher on the STAI-state displayed a significantly more sensitive HPA-system, resulting in salivary cortisol concentration increases after real HF-rTMS, compared to those scoring lower on this anxiety scale. Our results indicate that healthy women scoring high on state anxiety display a more sensitive HPA-system when receiving one right-sided HF-rTMS session. Our findings suggest that the incorporation of individual anxiety states in experimental rTMS research could add further information about its neurobiological influences on the HPA-system.

Handedness, repetitive transcranial magnetic stimulation and bulimic disorders

Repetitive Transcranial Magnetic Stimulation (rTMS) research in psychiatry mostly excludes left-handed participants. We recruited left-handed people with a bulimic disorder and found that stimulation of the left prefrontal cortex may result in different effects in left- and right-handed people. This highlights the importance of handedness and cortex lateralisation for rTMS.

Influence of high-frequency repetitive transcranial magnetic stimulation over the dorsolateral prefrontal cortex on the inhibition of emotional information in healthy volunteers

BACKGROUND

Evidence suggests that repetitive transcranial magnetic stimulation (rTMS) over the left dorsolateral prefrontal cortex (DLPFC) might be a promising new treatment procedure for depression. However, underlying working mechanisms of this technique are yet unclear. Multiple sessions of rTMS may--apart from the reported antidepressant effects--cause primary improvements in attentional control over emotional information, modulated by changes in cortical brain excitability within stimulated prefrontal regions.

METHOD

In two experiments, we examined the temporary effects of high-frequency (HF) rTMS (10 Hz) applied over the left and right DLPFC on the attentional processing of emotional information and self-reported mood within samples of healthy volunteers.

RESULTS

The present study showed that one session of HF-rTMS over the right DLPFC produces instant impairments in the ability to inhibit negative information, in line with a characteristic cognitive vulnerability found in depressive pathology, whereas HF-rTMS of the left DLPFC did not lead to significant changes in attentional control. These effects could not be attributed to mood changes.

CONCLUSIONS

The findings of the present study may suggest a specific involvement of the right DLPFC in the attentional processing of emotional information.

The impact of one HF-rTMS session on mood and salivary cortisol in treatment resistant unipolar melancholic depressed patients

BACKGROUND

Recent studies indicate that medication resistant depressed patients can be successfully treated by a series of sessions of High Frequency repetitive Transcranial Magnetic Stimulation (HF-rTMS), delivered on the left dorsolateral prefrontal cortex (DLPFC). However, changes in subjectively experienced mood give only limited insight into the underlying physiological responses. Previous studies in depressed patients, as well as in healthy volunteers, have reported a possible impact of HF-rTMS on the hypothalamic-pituitary-adrenal (HPA) axis.

OBJECTIVE

We wanted to evaluate the emotional and neurobiological impact of one session of HF-rTMS applied on the left DLPFC in a sample of unipolar treatment resistant depressed patients of the melancholic subtype.

METHODS

20 right-handed antidepressant-free depressed patients were studied using a sham-controlled, 'single' blind, crossover design. We examined subjective mood changes with Visual Analogue Scales (VAS). To examine HF-rTMS effects on the HPA-axis, we analyzed salivary cortisol levels. Mood assessment and salivary cortisol levels were assessed before and immediately after stimulation. To detect any delayed effects, all measurements were also re-assessed 30 min post HF-rTMS. The left DLPFC was determined under MRI guidance.

RESULTS

One session of HF-rTMS did not result in any subjectively experienced mood changes. However, salivary cortisol concentrations decreased significantly immediately and 30 min after active HF-rTMS.

CONCLUSIONS

Although one session of HF-rTMS on the left DLPFC did not influence mood subjectively in melancholic unipolar depressed patients, we found support for the hypothesis that a single session has a significant impact on the HPA-axis, as measured by salivary cortisol. Our results may provide more insight into the underlying working mechanisms of HF-rTMS in unipolar melancholic depression, and could add further information about endocrinological functioning in affective disorders.