Predictive value of brain perfusion SPECT for rTMS response in pharmacoresistant depression

Neurophysiological and neuroimaging markers of repetitive transcranial magnetic stimulation treatment response in major depressive disorder: A systematic review and meta-analysis of predictive modeling studies

Predicting repetitive transcranial magnetic stimulation (rTMS) treatment outcomes in major depressive disorder (MDD) could reduce the financial and psychological risks of treatment failure. We systematically reviewed and meta-analyzed studies that leveraged neurophysiological and neuroimaging markers to predict rTMS response in MDD. Five databases were searched from inception to May 25, 2023. The primary meta-analytic outcome was predictive accuracy pooled from classification models. Regression models were summarized qualitatively. A promising marker was identified if it showed a sensitivity and specificity of 80% or higher in at least two independent studies. Searching yielded 36 studies. Twenty-two classification modeling studies produced an estimated area under the summary receiver operating characteristic curve of 0.87 (95% CI = 0.83-0.92), with 86.8% sensitivity (95% CI = 80.6-91.2%) and 81.9% specificity (95% CI = 76.1-86.4%). Frontal theta cordance measured by electroencephalography is closest to proof of concept. Predicting rTMS response using neurophysiological and neuroimaging markers is promising for clinical decision-making. However, replications by different research groups are needed to establish rigorous markers.

Assessing the impact of sex on high-frequency repetitive transcranial magnetic stimulation´s clinical response in schizophrenia - results from a secondary analysis

BACKGROUND

The evidence for repetitive transcranial magnetic stimulation (rTMS) to treat negative symptoms in schizophrenia (SCZ) is increasing, although variable response rates remain a challenge. Subject´s sex critically influences rTMS´ treatment outcomes. Females with major depressive disorder are more likely to respond to rTMS, while SCZ data is scarce.

METHODS

Using data from the 'rTMS for the Treatment of Negative Symptoms in Schizophrenia' (RESIS) trial we assessed the impact of sex on rTMS´ clinical response rate from screening up to 105 days after intervention among SCZ patients. The impact of resting motor threshold (RMT) on response rates was also assessed.

RESULTS

157 patients received either active or sham rTMS treatment. No significant group differences were observed. Linear mixed model showed no effects on response rates (all p > 0.519). Apart from a significant sex*time interaction for the positive subscale of the positive and negative syndrome scale (PANSS) scores (p = 0.032), no other significant effects of sex on continuous PANSS scores were observed. RMT had no effect on response rate.

CONCLUSION

In the largest rTMS trial on the treatment of SCZ negative symptoms we did not observe any significant effect of sex on treatment outcomes. Better assessments of sex-related differences could improve treatment individualisation.

Regional cerebral blood flow at rest in schizophrenia and major depressive disorder: A functional neuroimaging meta-analysis

Severe mental disorders (SMDs) such as schizophrenia (SCZ), major depressive disorder (MDD) and bipolar disorder (BD) are associated with altered brain function. Neuroimaging studies have illustrated spontaneous activity alterations across SMDs, but no meta-analysis has directly compared resting-state regional cerebral blood flow (rCBF) with one another. We conducted a meta-analysis of PET, SPECT and ASL neuroimaging studies to identify specific alterations of rCBF at rest in SMDs. Included are 20 studies in MDD, and 18 studies in SCZ. Due to the insufficient number of studies in BD, this disorder was left out of the analyses. Compared to controls, the SCZ group displayed reduced rCBF in the triangular part of the left inferior frontal gyrus and in the medial orbital part of the bilateral superior frontal gyrus. After correction, only a small cluster in the right inferior frontal gyrus exhibited reduced rCBF in MDD, compared to controls. Differences were found in these brain regions between SCZ and MDD. SCZ displayed reduced rCBF at rest in regions associated with default-mode, reward processing and language processing. MDD was associated with reduced rCBF in a cluster involved in response inhibition. Our meta-analysis highlights differences in the resting-state rCBF alterations between SCZ and MDD.

Irremediability in psychiatric euthanasia: examining the objective standard

BACKGROUND

Irremediability is a key requirement for euthanasia and assisted suicide for psychiatric disorders (psychiatric EAS). Countries like the Netherlands and Belgium ask clinicians to assess irremediability in light of the patient's diagnosis and prognosis and 'according to current medical understanding'. Clarifying the relevance of a default objective standard for irremediability when applied to psychiatric EAS is crucial for solid policymaking. Yet so far, a thorough examination of this standard is lacking.

METHODS

Using treatment-resistant depression (TRD) as a test case, through a scoping review in PubMed, we analyzed the state-of-the-art evidence for whether clinicians can accurately predict individual long-term outcome and single out irremediable cases, by examining the following questions: (1) What is the definition of TRD; (2) What are group-level long-term outcomes of TRD; and (3) Can clinicians make accurate individual outcome predictions in TRD?

RESULTS

A uniform definition of TRD is lacking, with over 150 existing definitions, mostly focused on psychopharmacological research. Available yet limited studies about long-term outcomes indicate that a majority of patients with long-term TRD show significant improvement over time. Finally, evidence about individual predictions in TRD using precision medicine is growing, but methodological shortcomings and varying predictive accuracies pose important challenges for its implementation in clinical practice.

CONCLUSION

Our findings support the claim that, as per available evidence, clinicians cannot accurately predict long-term chances of recovery in a particular patient with TRD. This means that the objective standard for irremediability cannot be met, with implications for policy and practice of psychiatric EAS.

Neuroimaging Correlates of Treatment Response to Transcranial Magnetic Stimulation in Bipolar Depression: A Systematic Review

Transcranial magnetic stimulation (TMS) has become a promising strategy for bipolar disorder (BD). This study reviews neuroimaging findings, indicating functional, structural, and metabolic brain changes associated with TMS in BD. Web of Science, Embase, Medline, and Google Scholar were searched without any restrictions for studies investigating neuroimaging biomarkers, through structural magnetic resonance imaging (MRI), diffusion tensor imaging (DTI), functional MRI (fMRI), magnetic resonance spectroscopy (MRS), positron emission tomography (PET), and single photon emission computed tomography (SPECT), in association with response to TMS in patients with BD. Eleven studies were included (fMRI = 4, MRI = 1, PET = 3, SPECT = 2, and MRS = 1). Important fMRI predictors of response to repetitive TMS (rTMS) included higher connectivity of emotion regulation and executive control regions. Prominent MRI predictors included lower ventromedial prefrontal cortex connectivity and lower superior frontal and caudal middle frontal volumes. SPECT studies found hypoconnectivity of the uncus/parahippocampal cortex and right thalamus in non-responders. The post-rTMS changes using fMRI mostly showed increased connectivity among the areas neighboring the coil. Increased blood perfusion was reported post-rTMS in PET and SPECT studies. Treatment response comparison between unipolar depression and BD revealed almost equal responses. Neuroimaging evidence suggests various correlates of response to rTMS in BD, which needs to be further replicated in future studies.

Molecular imaging findings for treatment resistant depression

Approximately 40% of patients with major depressive disorder (MDD) had limited response to conventional antidepressant treatments, resulting in treatment-resistant depression (TRD), a debilitating subtype that yielded a significant disease burden worldwide. Molecular imaging techniques, such as positron emission tomography (PET) and single photon emission tomography (SPECT), can measure targeted macromolecules or biological processes in vivo. These imaging tools provide a unique possibility to explore the pathophysiology and treatment mechanisms underlying TRD. This work reviewed and summarized prior PET and SPECT studies to examine the neurobiology and treatment-induced changes of TRD. A total of 51 articles were included with supplementary information from studies for MDD and healthy controls (HC). We found that there were altered regional blood flow or metabolic activity in several brain regions, such as the anterior cingulate cortex, prefrontal cortex, insula, hippocampus, amygdala, parahippocampus, and striatum. These regions have been suggested to engage in the pathophysiology or treatment resistance of depression. There was also limited data to demonstrate the changes in the markers of serotonin, dopamine, amyloid, and microglia over some regions in TRD. Moreover, several observed abnormal imaging indices were linked to treatment outcomes, supporting their specificity and clinical relevance. To address the limitations of the included studies, we proposed that future studies needed longitudinal designs, multimodal approaches, and radioligands targeting specific neural substrates for TRD to evaluate their baseline and treatment-related alterations in TRD. Adequate data sharing and reproducible data analysis can facilitate advances in this field.

Predictors of remission after repetitive transcranial magnetic stimulation for the treatment of major depressive disorder: An analysis from the randomised non-inferiority THREE-D trial

BACKGROUND

Although repetitive transcranial magnetic stimulation (rTMS) is an effective treatment for major depressive disorder (MDD), treatment selection is still mainly a process of trial-and-error. The present study aimed to identify clinical predictors of remission after a course of rTMS delivered to the left DLPFC to improve patient selection.

METHODS

Data from a large randomised non-inferiority trial comparing standard 10 Hz and intermittent theta burst stimulation (iTBS) for the treatment of MDD were used for the exploratory analyses. Individual variables were assessed for their association with remission and then included in a logistic regression model to determine odds ratios (OR) and corresponding 95% confidence intervals. Model discrimination (internal validation) was carried out to assess model optimism using the c-index. ClinicalTrials.gov identifier: NCT01887782.

FINDINGS

388 subjects were included in the analysis (199-iTBS and 189-10 Hz, respectively). Higher baseline severity of both depressive and anxiety symptoms were associated with a lower chance of achieving remission (OR=0.64, 95% CI 0.46-0.88; and 0.78, 95% CI 0·60-0.98, respectively). Current employment was a positive predictor for remission (OR=1.69, 95% CI 1.06-2.7), while greater number of treatment failures was associated with lower odds of achieving remission (OR=0.51, 95% CI 0.27-0.98). A non-linear effect of age and remission was observed. An analysis to allow an estimate of the probability of remission using all variables was assessed. The c-index for the fitted model was 0.687.

INTERPRETATION

Our results suggest that measuring depression symptom severity, employment status, and refractoriness are important in prognosticating outcome to a course of rTMS in MDD.

FUNDING

Canadian Institutes of Health Research MOP-136801.

Baseline Difference in Quantitative Electroencephalography Variables Between Responders and Non-Responders to Low-Frequency Repetitive Transcranial Magnetic Stimulation in Depression

Repetitive transcranial magnetic stimulation (rTMS) is an effective treatment for depressive disorder, with outcomes approaching 45-55% response and 30-40% remission. Eligible predictors of treatment outcome, however, are still lacking. Few studies have investigated quantitative electroencephalography (QEEG) parameters as predictors of rTMS treatment outcome and none of them have addressed the source localization techniques to predict the response to low-frequency rTMS (LF rTMS). We investigated electrophysiological differences based on scalp EEG data and inverse solution method, exact low-resolution brain electromagnetic tomography (eLORETA), between responders and non-responders to LF rTMS in resting brain activity recorded prior to the treatment. Twenty-five unmedicated depressive patients (mean age of 45.7 years, 20 females) received a 4-week treatment of LF rTMS (1 Hz; 20 sessions per 600 pulses; 100% of the motor threshold) over the right dorsolateral prefrontal cortex. Comparisons between responders (≥50% reduction in Montgomery-Åsberg Depression Rating Scale score) and non-responders were made at baseline for measures of eLORETA current density, spectral absolute power, and inter-hemispheric and intra-hemispheric EEG asymmetry. Responders were found to have lower current source densities in the alpha-2 and beta-1 frequency bands bilaterally (with predominance on the left side) in the inferior, medial, and middle frontal gyrus, precentral gyrus, cingulate gyrus, anterior cingulate, and insula. The most pronounced difference was found in the left middle frontal gyrus for alpha-2 and beta-1 bands (p < 0.05). Using a spectral absolute power analysis, we found a negative correlation between the absolute power in beta and theta frequency bands on the left frontal electrode F7 and the change in depressive symptomatology. None of the selected asymmetries significantly differentiated responders from non-responders in any frequency band. Pre-treatment reduction of alpha-2 and beta-1 sources, but not QEEG asymmetry, was found in patients with major depressive disorder who responded to LF rTMS treatment. Prospective trials with larger groups of subjects are needed to further validate these findings.

White matter integrity and functional predictors of response to repetitive transcranial magnetic stimulation for posttraumatic stress disorder and major depression

BACKGROUND

Recent evidence suggests that therapeutic repetitive transcranial magnetic stimulation (TMS) is an effective treatment for pharmacoresistant posttraumatic stress disorder (PTSD) and comorbid major depressive disorder (MDD). We recently demonstrated that response to 5 Hz TMS administered to the dorsolateral prefrontal cortex was predicted by functional connectivity of the medial prefrontal (MPFC) and subgenual anterior cingulate cortex (sgACC). This functionally-defined circuit is a novel target for treatment optimization research, however, our limited knowledge of the structural pathways that underlie this functional predisposition is a barrier to target engagement research.

METHODS

To investigate underlying structural elements of our previous functional connectivity findings, we submitted pre-TMS diffusion-weighted imaging data from 20 patients with PTSD and MDD to anatomically constrained tract-based probabilistic tractography (FreeSurfer's TRActs Constrained by UnderLying Anatomy). Averaged pathway fractional anisotropy (FA) was extracted from four frontal white matter tracts: the forceps minor, cingulum, anterior thalamic radiations (ATRs), and uncinate fasciculi. Tract FA statistics were treated as explanatory variables in backward regressions testing the relationship between tract integrity and functional connectivity coefficients from MPFC and sgACC predictors of symptom improvement after TMS.

RESULTS

FA in the ATRs was consistently associated with symptom improvement in PTSD and MDD (Bonferroni-corrected p < .05).

CONCLUSION

We found that structural characteristics of the ATR account for significant variance in individual-level functional predictors of post-TMS improvement. TMS optimization studies should target this circuit either in stand-alone or successive TMS stimulation protocols.

Use of Transcranial Magnetic Stimulation for Depression

Transcranial magnetic stimulation (TMS), a research tool with various effects on brain cells, can depolarize cerebral neurons noninvasively. This method offers temporal and spatial resolution and can be combined with other neurocognitive and neuro-experimental techniques. Prefrontal TMS therapy repeated daily for four to six weeks is a neuromodulation technique approved by the US Food and Drug Administration for the treatment of major depressive disorder (MDD) in patients resistant to medications. This technique utilizes electromagnetic induction to excite neuronal cells. Several recent studies have enhanced our understanding of this novel treatment intervention. This report reviews recent studies on the mechanism of action, patient eligibility, effectiveness, and safety of TMS in treating depression.

Functional neuroimaging in patients presenting with somatoform disorders: A model for investigating persisting symptoms after tick bites and post-treatment Lyme disease syndrome?

Approximately 10% of patients presenting with Lyme disease experience fatigue, musculoskeletal pain, concentration disorders, or short-term memory deficits in the six months following treatment. This entity has been defined as post-Lyme disease syndrome or post-treatment Lyme disease syndrome. The pathophysiology of this syndrome is unknown, but neither persistence of the bacterium nor effectiveness of antibiotics are currently reported in the literature. The French High Council for Public Health (French acronym HCSP) has recently defined a new entity called "persistent polymorphic symptoms after a tick bite" allowing for designing studies to better understand these subjective presentations, for which objective biomarkers are currently lacking. This entity encompasses patients experiencing fatigue and generalized pain in the months following a tick bite and can be associated with several subjective symptoms with major impact on the quality of life. In the field of somatoform disorders, this article reviews functional neuroimaging studies in patients presenting with subjective complaints and discusses potential clinical implications for persisting symptoms after tick bites and post-treatment Lyme disease syndrome.

Increase of frontal cerebral blood volume during transcranial magnetic stimulation in depression is related to treatment effectiveness: A pilot study with near-infrared spectroscopy

AIM

Alterations of cerebral blood flow have been reported in studies of depression treated by transcranial magnetic stimulation (TMS). However, the relation between these changes in activity during stimulation and the effectiveness of TMS is not known. The aim of this study was to determine whether changes in frontal cerebral blood volume measured as frontal hemoglobin concentration (fHbC) during TMS are correlated with clinical outcomes of treatment.

METHODS

Fifteen drug-resistant patients with depression underwent a standard treatment regimen of TMS to the left dorsolateral prefrontal cortex. We recorded fHbC during stimulation at the start and end of the TMS treatment series using near-infrared spectroscopy. Symptom severity was determined using the Montgomery-Åsberg Depression Rating Scale.

RESULTS

At the start of the TMS series, fHbC increased during stimulation in a majority of patients with no relation to symptom severity. However, at the end of the series, fHbC increase during stimulation was negatively correlated with the Montgomery-Åsberg Depression Rating Scale score and positively with the score reduction. Patients showing a decreasing response of fHbC during TMS at the end of the series experienced less clinical improvement.

CONCLUSION

These results suggest that the maintenance of frontal activation during stimulation in the course of TMS series is related to the effectiveness in the treatment of depression. Measurement of fHbC during stimulation is informative in the clinical use of TMS.

Multimodal Molecular Imaging: Current Status and Future Directions

Molecular imaging has emerged at the end of the last century as an interdisciplinary method involving in vivo imaging and molecular biology aiming at identifying living biological processes at a cellular and molecular level in a noninvasive manner. It has a profound role in determining disease changes and facilitating drug research and development, thus creating new medical modalities to monitor human health. At present, a variety of different molecular imaging techniques have their advantages, disadvantages, and limitations. In order to overcome these shortcomings, researchers combine two or more detection techniques to create a new imaging mode, such as multimodal molecular imaging, to obtain a better result and more information regarding monitoring, diagnosis, and treatment. In this review, we first describe the classic molecular imaging technology and its key advantages, and then, we offer some of the latest multimodal molecular imaging modes. Finally, we summarize the great challenges, the future development, and the great potential in this field.

Predictive value of dorso-lateral prefrontal connectivity for rTMS response in treatment-resistant depression: A brain perfusion SPECT study

BACKGROUND

Previous clinical trials have suggested that repetitive transcranial magnetic stimulation (rTMS) has a significant antidepressant effect in patients with treatment resistant depression (TRD). However, results remain heterogeneous with many patients without effective response.

OBJECTIVE

The aim of this SPECT study was to determine before treatment the predictive value of the connectivity of the stimulated area on further rTMS response in patients with TRD.

METHODS

Fifty-eight TRD patients performed a brain perfusion SPECT before high frequency rTMS of the left dorsolateral prefrontal cortex (DLPFC). A voxel based-analysis was achieved to compare connectivity of the left DLPFC in responders and non-responders using inter-regional correlations (p < 0.005, corrected for cluster volume). A multiple logistic regression model was thereafter used with the goal of establishing a predictive score.

RESULTS

Before rTMS, responders exhibited increased SPECT connectivity between the left DLPFC and the right cerebellum in comparison to non-responders, independently of age, gender, severity of depression, and severity of treatment resistance. The area under the curve for the combination of these two SPECT clusters to predict rTMS response was 0.756 (p < 0.005).

CONCLUSIONS

SPECT connectivity of the left DLPFC predicts rTMS response before treatment.

Changes in canine cerebral perfusion after accelerated high frequency repetitive transcranial magnetic stimulation (HF-rTMS): A proof of concept study

Repetitive transcranial magnetic stimulation (rTMS) has been proposed as a treatment for several neuropsychiatric disorders in human beings, but the neurobiological effects of rTMS in dogs have not been investigated to date. A proof of concept study was designed to evaluate the effect of rTMS on cerebral perfusion, measured with single photon emission computed tomography (SPECT), in dogs. An accelerated high frequency (aHF)-rTMS (20Hz) protocol was applied to the canine left frontal cortex. To accurately target this area, eight dogs underwent a 3 Tesla magnetic resonance imaging (MRI) scan before stimulation. The left frontal cortex was subjected to five consecutive aHF-rTMS sessions with a figure-of-eight coil designed for human beings at an intensity of 110% of the motor threshold. The dogs underwent ^99mTc-d,1 hexamethylpropylene amine oxime (HMPAO) SPECT scans 1 week prior to and 1day after the stimulations. Perfusion indices (PIs) were determined semi-quantitatively; aHF-rTMS resulted in significantly increased PIs in the left frontal cortex and the subcortical region, whereas no significant differences were noted for the other regions. Behaviour was not influenced by the stimulation sessions. As has been observed in human beings, aHF-rTMS applied to the left frontal cortex alters regional cerebral perfusion in dogs.

Longer depressive episode duration negatively influences HF-rTMS treatment response: a cerebellar metabolic deficiency?

Repetitive transcranial magnetic stimulation (rTMS) is an evidence based neurostimulation modality used to treat patients with Major Depressive Disorder (MDD). In spite that the duration of current a depressive episode has been put forward as a negative predictor for clinical outcome, little is known about the underlying neurobiological mechanisms of this phenomenon. To address this important issue, in a sample of 43 melancholic stage III treatment resistant antidepressant-free refractory MDD patients, we reanalysed regional cerebral glucose metabolism (CMRglc) before high frequency (HF)-rTMS treatment, applied to the left dorsolateral prefrontal cortex (DLPFC). Besides that a lower baseline cerebellar metabolic activity indicated negative clinical response, a longer duration of the depressive episode was a negative indicator for recovery and negatively influenced cerebellar CMRglc. This exploratory ¹⁸FDG PET study is the first to demonstrate that the clinical response of HF-rTMS treatment in TRD patients may depend on the metabolic state of the cerebellum. Our observations could imply that for left DLPFC HF-rTMS non-responders other brain localisations for stimulation, more specifically the cerebellum, may be warranted.

Defining functioning levels in patients with schizophrenia: A combination of a novel clustering method and brain SPECT analysis

This study aims to define functioning levels of patients with schizophrenia by using a method of interpretable clustering based on a specific functioning scale, the Functional Remission Of General Schizophrenia (FROGS) scale, and to test their validity regarding clinical and neuroimaging characterization. In this observational study, patients with schizophrenia have been classified using a hierarchical top-down method called clustering using unsupervised binary trees (CUBT). Socio-demographic, clinical, and neuroimaging SPECT perfusion data were compared between the different clusters to ensure their clinical relevance. A total of 242 patients were analyzed. A four-group functioning level structure has been identified: 54 are classified as "minimal", 81 as "low", 64 as "moderate", and 43 as "high". The clustering shows satisfactory statistical properties, including reproducibility and discriminancy. The 4 clusters consistently differentiate patients. "High" functioning level patients reported significantly the lowest scores on the PANSS and the CDSS, and the highest scores on the GAF, the MARS and S-QoL 18. Functioning levels were significantly associated with cerebral perfusion of two relevant areas: the left inferior parietal cortex and the anterior cingulate. Our study provides relevant functioning levels in schizophrenia, and may enhance the use of functioning scale.

Anaesthesia, not number of sessions, influences the magnitude and duration of an aHF-rTMS in dogs

BACKGROUND

Currently, the rat has been a useful animal model in brain stimulation research. Nevertheless, extrapolating results from rodent repetitive Transcranial Magnetic Stimulation (rTMS) research to humans contains several hurdles. This suggests the desperate need for a large animal model in translational rTMS research. The dog would be a valid choice, not only due to the fact that humans and dogs share a neurophysiological background, but a similar neuropathological background as well.

HYPOTHESIS

In order to evaluate the feasibility of the canine rTMS animal model, this study aimed to evaluate the neurophysiological response in dogs on a, clinically used, accelerated high frequency (aHF) rTMS protocol. This aHF-rTMS (20 Hz) protocol was performed under anaesthesia or sedation and either 20 sessions or 5 sessions were given to each dog.

METHODS

21 healthy dogs were randomly subjected to one of the four aHF-rTMS protocols (1 sham and 3 active protocols). For each dog, the perfusion indices (PI), of a [99mTc]HMPAO scan at 4 time points, for the left frontal cortex (stimulation target) were calculated for each protocol.

RESULTS

Concerning sham stimulation, the average PI remained at the baseline level. The main result was the presence of a direct transitory increase in rCBF at the stimulation site, both under anaesthesia and sedation. Nevertheless the measured increase in rCBF was higher but shorter duration under sedation. The magnitude of this increase was not influenced by number of sessions. No changes in rCBF were found in remote brain regions.

CONCLUSION

This study shows that, despite the influence of anaesthesia and sedation, comparable and clinically relevant effects on the rCBF can be obtained in dogs. Since less methodological hurdles have to be overcome and comparable results can be obtained, it would be acceptable to put the dog forward as an alternative translational rTMS animal model.

Clinical and demographic predictors of response to rTMS treatment in unipolar and bipolar depressive disorders

OBJECTIVE

Previous studies investigated predictors of repetitive transcranial magnetic stimulation (rTMS) response in depressive disorders but there is still limited knowledge about clinical predictors. Moreover, predictors of rTMS response in bipolar depression (BDD) are less studied than unipolar depression (UDD).

METHODS

We performed a binary logistic regression analysis in 248 patients with depressive disorders (unipolar N=102, bipolar N=146) who received 20 sessions of DLPFC rTMS (High-frequency rTMS, low-frequency rTMS, bilateral rTMS) to investigate significant clinical and demographic predictors of rTMS response. We also investigated effects of depression type, response (yes, no) and time on reducing somatic and cognitive-affective symptoms of patients.

RESULTS

Depression type (unipolar vs. bipolar) did not have a significant effect on rTMS response. 45% of all patients, 51.5% of UDD patients and 41% of BDD patients, responded to rTMS treatment. Age was the only significant demographic predictor of treatment response in all patients. Cognitive-affective symptoms, compared to somatic symptoms were significant predictors for treatment response to rTMS. Common and unique clinical predictor for UDD and BDD were identified.

CONCLUSIONS

Younger patients and those with cognitive-affective rather than somatic symptoms benefit more from DLPFC rTMS treatment. rTMS is effective in UDD and BDD patients. Patients should be selected based on clinical and demographic profile.

SIGNIFICANCE

Findings are based on the largest thus far reported sample of patients with depressive disorders that received DLPFC rTMS.

Microstructural Abnormalities of Basal Ganglia and Thalamus in Bipolar and Unipolar Disorders: A Diffusion Kurtosis and Perfusion Imaging Study

OBJECTIVE

Bipolar disorder (BD) is often misdiagnosed as unipolar depression (UD), leading to mistreatment and poor clinical outcomes. However, little is known about the similarities and differences in subcorticalgray matter regions between BD and UD.

METHODS

Thirty-five BD patients, 30 UD patients and 40 healthy controls underwent diffusional kurtosis imaging (DKI) and three dimensional arterial spin labeling (3D ASL). The parameters including mean kurtosis (MK), axial kurtosis (Ka), radial kurtosis (Kr), fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (Da), radial diffusivity (Dr) and cerebral blood flow (CBF) were measured by using regions-of-interest analysis in the caudate, putamen and thalamus of the subcortical gray matter regions.

RESULTS

UD exhibited differences from controls for DKI measures and CBF in the left putamen and caudate. BD showed differences from controls for DKI measures in the left caudate. Additionally, BD showed lower Ka in right putamen, higher MD in right caudate compared with UD. Receiver operating characteristic analysis revealed the Kr of left caudate had the highest predictive power for distinguishing UD from controls.

CONCLUSION

The two disorders may have overlaps in microstructural abnormality in basal ganglia. The change of caudate may serve as a potential biomarker for UD.

Changes in dorsolateral prefrontal connectivity after rTMS in treatment-resistant depression: a brain perfusion SPECT study

PURPOSE

Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive and safe alternative to electroconvulsive therapy for treatment-resistant depression (TRD). After rTMS, changes in brain SPECT perfusion have been remotely identified within medial temporal limbic areas, while no local effects have been found within the left dorsolateral prefrontal cortex (DLPFC)-i.e. under the coil. Functional changes in connectivity may underlie these remote effects. Interestingly, functional connectivity has been recently investigated using perfusion SPECT, and abnormalities identified in TRD patients. The aim of the present study is to evaluate perfusion and connectivity SPECT changes in TRD patients after rTMS of the left DLPFC. We hypothesize that changes in DLPFC networks may explain remote hypoperfusions found after rTMS.

METHODS

Fifty-eight TRD patients underwent a brain SPECT before and after high-frequency rTMS of the left DLPFC. Whole-brain voxel-based changes in perfusion were evaluated with SPM8, and inter-regional correlation analysis performed to study left DLPFC functional connectivity (p < 0.005, corrected for cluster volume).

RESULTS

After rTMS, patients were significantly improved on Beck Depression Inventory score (p < 0.0001). Considering a 50% reduction threshold, 27 patients were identified as responders (47%). After rTMS, perfusion changes were not found locally within the left DLPFC, but remotely within the bilateral temporal lobes, including limbic areas. Inter-regional correlation SPECT analysis brings out a decrease of connectivity between the left DLPFC and both the cingulate/medial frontal cortex and bilateral medial temporal limbic areas, in relation with the clinical response.

CONCLUSIONS

rTMS of DLPFC in TRD patients leads to remote temporal hypoperfusions in relation with changes in functional connectivity between the DLPFC and the default mode network, especially including medial temporal limbic areas.

Acute Stressors Reduce Neural Inhibition to Food Cues and Increase Eating Among Binge Eating Disorder Symptomatic Women

Stressors can trigger binge-eating but researchers have yet to consider their effects on both neural responses to food cues and food consumption among those at risk. In this experiment, we examined the impact of acute stressors on neural activation to food images and subsequent food consumption within binge-eating disorder (BED) and non-eating disordered control groups. Eighteen women meeting DSM-IV BED criteria and 26 women serving as non-eating disordered controls were randomly assigned to unpleasant stressor (painful cold pressor test (CPT) followed by negative performance feedback) or less unpleasant stressor (non-painful sensory discrimination task followed by positive performance feedback) conditions. Subsequently, they were scanned with functional magnetic resonance imaging (fMRI) while viewing food and neutral images. After the scans, participants completed a self-report battery in an environment conducive to snacking. During exposure to food images, BED-symptomatic women in the unpleasant stressor condition reported more liking of high calorie food images and showed less activation in one inhibitory area, the hippocampus, compared to controls in this condition. BED-symptomatic women exposed to unpleasant stressors also consumed more chocolate than any other group during the post-scan questionnaire completion. Crucially, reduced hippocampal activation to high calorie food images predicted more chocolate consumption following fMRI scans within the entire sample. This experiment provides initial evidence suggesting unpleasant acute stressors contribute to reduced inhibitory region responsiveness in relation to external food cues and later food consumption among BED-symptomatic women.

Brain SPECT guided repetitive transcranial magnetic stimulation (rTMS) in treatment resistant major depressive disorder

Repetitive transcranial magnetic stimulation (rTMS) has emerged as a potential treatment in treatment resistant major depressive disorder (MDD). However, there is no consensus about the exact site of stimulation for rTMS. Single-photon emission computed tomography (SPECT) offers a potential technique in deciding the site of stimulation. The present study was conducted to assess the difference in outcome of brain SPECT assisted rTMS versus standard protocol of twenty sessions of high frequency rTMS as add on treatment in 20 patients with treatment resistant MDD, given over a period of 4 weeks. Thirteen subjects (group I) received high frequency rTMS over an area of hypoperfusion in the prefrontal cortex, as identified on SPECT, whereas 7 subjects (group II) were administered rTMS in the left dorsoslateral prefrontal cortex (DLPFC) area. Improvement was monitored using standardized instruments. Patients in the group I showed a significantly better response compared to those in the group II. In group I, 46% of the subjects were responders on MADRS, 38% on BDI and 77% on CGI. The parallel figures of responders in Group II were 0% on MADRS, 14% on BDI and 43% on CGI. There were no remitters in the study. No significant untoward side effects were noticed. The study had limitations of a small sample size and non-controlled design, and all the subjects were also receiving the standard antidepressant therapy. Administration of rTMS over brain SPECT specified area of hypoperfusion may have a better clinical outcome compared to the standard protocol.

Use of the Temperament and Character Inventory to Predict Response to Repetitive Transcranial Magnetic Stimulation for Major Depression

OBJECTIVE

The goal of this study was to investigate the utility of the Temperament and Character Inventory (TCI) in predicting antidepressant response to repetitive transcranial magnetic stimulation (rTMS).

BACKGROUND

Although rTMS of the dorsolateral prefrontal cortex is an established antidepressant treatment, little is known about predictors of response. The TCI measures multiple personality dimensions (harm avoidance, novelty seeking, reward dependence, persistence, self-directedness, self-transcendence, and cooperativeness), some of which have predicted response to pharmacotherapy and cognitive-behavioral therapy. A previous study suggested a possible association between self-directedness and response to rTMS in melancholic depression, although this was limited by the fact that melancholic depression is associated with a limited range of TCI profiles.

METHODS

Nineteen patients with a major depressive episode completed the TCI before a clinical course of rTMS over the dorsolateral prefrontal cortex. Treatment response was defined as ≥50% decrease in scores on the Hamilton Rating Scale for Depression (Ham-D). Baseline scores on each TCI dimension were compared between responders and nonresponders through analysis of variance. Pearson correlations were also calculated for temperament/character scores in comparison with percentage improvement in Ham-D scores.

RESULTS

Eleven of the 19 patients responded to rTMS. T-scores for persistence were significantly higher in responders than in nonresponders (P=0.022). Linear regression revealed a correlation between persistence scores and percentage improvement in Ham-D scores.

CONCLUSIONS

Higher persistence scores predicted antidepressant response to rTMS. This may be explained by rTMS-induced enhancement of cortical excitability, which has been found to be decreased in patients with high persistence. Personality assessment that includes measurement of TCI persistence may be a useful component of precision medicine initiatives in rTMS for depression.

Functional brain substrate of quality of life in patients with schizophrenia: A brain SPECT multidimensional analysis

The aim of this study was to investigate the functional brain substrate of quality of life (QoL) in patients with schizophrenia. Participants comprised 130 right-handed patients with schizophrenia who underwent whole-brain single photon emission computed tomography (SPECT) with (99m)Tc-labeled ethylcysteinate dimer ((99m)Tc-ECD) for exploring correlations of regional cerebral blood flow (rCBF) with the eight dimensions score of the Schizophrenia Quality of Life questionnaire (S-QoL 18). A significant positive correlation was found between the global index of the S-QoL 18 and rCBF in the right superior temporal sulcus and between psychological well-being dimension and rCBF in Brodmann area (BA)6, BA8, BA9, and BA10 and between self-esteem dimension and rCBF in striatum and between family relationship dimension and rCBF in BA1, BA2, BA3, BA4, BA8, BA22, BA40, BA42 and BA44 and between relationship with friends dimension and rCBF in BA44 and between physical well-being dimension and rCBF in parahippocampal gyrus, and finally between autonomy dimension and rCBF in cuneus and precuneus. A significant negative correlation was found between resilience dimension and rCBF in precuneus and between sentimental life dimension and rCBF in BA10. Our findings provide neural correlates of QoL. Brain regions involved in cognitions, emotional information processing and social cognition underlie the different QoL dimensions.

NEUROBIOLOGICAL PREDICTORS OF RESPONSE TO DORSOLATERAL PREFRONTAL CORTEX REPETITIVE TRANSCRANIAL MAGNETIC STIMULATION IN DEPRESSION: A SYSTEMATIC REVIEW

BACKGROUND

A significant proportion of patients with depression fail to respond to psychotherapy and standard pharmacotherapy, leading to treatment-resistant depression (TRD). Due to the significant prevalence of TRD, alternative therapies for depression have emerged as viable treatments in the armamentarium for this disorder. Repetitive transcranial magnetic stimulation (rTMS) is now being offered in clinical practice in broader numbers. Many studies have investigated various different neurobiological predictors of response of rTMS. However, a synthesis of this literature and an understanding of what biological targets predict response is lacking. This review aims to systematically synthesize the literature on the neurobiological predictors of rTMS in patients with depression.

METHODS

Medline (1996-2014), Embase (1980-2014), and PsycINFO (1806-2014) were searched under set terms. Two authors reviewed each article and came to consensus on the inclusion and exclusion criteria. All eligible studies were reviewed, duplicates were removed, and data were extracted individually.

RESULTS

The search identified 1,673 articles, 41 of which met both inclusion and exclusion criteria. Various biological factors at baseline appear to predict response to rTMS, including levels of certain molecular factors, blood flow in brain regions implicated in depression, electrophysiological findings, and specific genetic polymorphisms.

CONCLUSIONS

Significant methodological variability in rTMS treatment protocols limits the ability to generalize conclusions. However, response to treatment may be predicted by baseline frontal lobe blood flow, and presence of polymorphisms of the 5-hydroxytryptamine (5-HT) -1a gene, the LL genotype of the serotonin transporter linked polymorphic region (5-HTTLPR) gene, and Val/Val homozygotes of the brain-derived neurotrophic factor (BDNF) gene.

Feature Selection and Classification of Electroencephalographic Signals: An Artificial Neural Network and Genetic Algorithm Based Approach

Feature selection is an important step in many pattern recognition systems aiming to overcome the so-called curse of dimensionality. In this study, an optimized classification method was tested in 147 patients with major depressive disorder (MDD) treated with repetitive transcranial magnetic stimulation (rTMS). The performance of the combination of a genetic algorithm (GA) and a back-propagation (BP) neural network (BPNN) was evaluated using 6-channel pre-rTMS electroencephalographic (EEG) patterns of theta and delta frequency bands. The GA was first used to eliminate the redundant and less discriminant features to maximize classification performance. The BPNN was then applied to test the performance of the feature subset. Finally, classification performance using the subset was evaluated using 6-fold cross-validation. Although the slow bands of the frontal electrodes are widely used to collect EEG data for patients with MDD and provide quite satisfactory classification results, the outcomes of the proposed approach indicate noticeably increased overall accuracy of 89.12% and an area under the receiver operating characteristic (ROC) curve (AUC) of 0.904 using the reduced feature set.

Abnormal Anterior Cingulate N-Acetylaspartate and Executive Functioning in Treatment-Resistant Depression After rTMS Therapy

BACKGROUND

Cognitive impairment is a key feature of treatment-resistant depression (TRD) and can be related to the anterior cingulate cortex (ACC) function. Repetitive transcranial magnetic stimulation (rTMS) as an antidepressant intervention has increasingly been investigated in the last two decades. However, no studies to date have investigated the association between neurobiochemical changes within the anterior cingulate and executive dysfunction measured in TRD being treated with rTMS.

METHODS

Thirty-two young depressed patients with treatment-resistant unipolar depression were enrolled in a double-blind, randomized study [active (n=18) vs. sham (n=14)]. ACC metabolism was investigated before and after high-frequency (15 Hz) rTMS using 3-tesla proton magnetic resonance spectroscopy (1H-MRS). The results were compared with 28 age- and gender-matched healthy controls. Executive functioning was measured with the Wisconsin Card Sorting Test (WCST) among 34 subjects with TRD and 28 healthy subjects.

RESULTS

Significant reductions in N-acetylaspartate (NAA) and choline-containing Compound levels in the left ACC were found in subjects with TRD pre-rTMS when compared with healthy controls. After successful treatment, NAA levels increased significantly in the left ACC of subjects and were not different from those of age-matched controls. In the WCST, more perseverative errors and fewer correct numbers were observed in TRD subjects at baseline. Improvements in both perseverative errors and correct numbers occurred after active rTMS. In addition, improvement of perseverative errors was positively correlated with enhancement of NAA levels in the left ACC in the active rTMS group.

CONCLUSIONS

Our results suggest that the NAA concentration in the left ACC is associated with an improvement in cognitive functioning among subjects with TRD response to active rTMS.

Determinants of brain SPECT perfusion and connectivity in treatment-resistant depression

This study aims to characterize and compare functional brain single photon emission tomography (SPECT) perfusion and connectivity in treatment-resistant depression (TRD) according to distinct demographic or clinical profiles (male vs. female; old vs. young; unipolar vs. bipolar) and to study their relationship to the severity and the duration of episode/illness. We retrospectively included 127 consecutive patients who met DSM-IV criteria for a nonpsychotic major TRD episode. All patients were studied using (99m)Tc-ethyl cysteinate dimer SPECT. Whole-brain, voxel-based, between-groups analyses were performed according to demographic and clinical data and in comparison to 37 healthy subjects. Voxel-wise interregional correlation was also performed to compare functional SPECT connectivity. Finally, relationships were searched for regarding severity and duration of episode/illness. The whole group of patients exhibited significant hypoperfusion within bilateral fronto-temporal, insular, and anterior cingulate cortices, as well as within the left caudate. Functional connectivity between left frontal and left cerebellar regions was higher in patients than in healthy subjects. Gender, age, and type of mood disorder did not influence these SPECT patterns. A significant relationship was found between brain SPECT perfusion and either duration or global severity of illness in particular frontal areas. Our data support the hypothesis of a shared SPECT pattern, whatever the profile of TRD, involving fronto-temporal regions and the cerebellum.

Neural Network Based Response Prediction of rTMS in Major Depressive Disorder Using QEEG Cordance

OBJECTIVE

The combination of repetitive transcranial magnetic stimulation (rTMS), a non-pharmacological form of therapy for treating major depressive disorder (MDD), and electroencephalogram (EEG) is a valuable tool for investigating the functional connectivity in the brain. This study aims to explore whether pre-treating frontal quantitative EEG (QEEG) cordance is associated with response to rTMS treatment among MDD patients by using an artificial intelligence approach, artificial neural network (ANN).

METHODS

The artificial neural network using pre-treatment cordance of frontal QEEG classification was carried out to identify responder or non-responder to rTMS treatment among 55 MDD subjects. The classification performance was evaluated using k-fold cross-validation.

RESULTS

The ANN classification identified responders to rTMS treatment with a sensitivity of 93.33%, and its overall accuracy reached to 89.09%. Area under Receiver Operating Characteristic (ROC) curve (AUC) value for responder detection using 6, 8 and 10 fold cross validation were 0.917, 0.823 and 0.894 respectively.

CONCLUSION

Potential utility of ANN approach method can be used as a clinical tool in administering rTMS therapy to a targeted group of subjects suffering from MDD. This methodology is more potentially useful to the clinician as prediction is possible using EEG data collected before this treatment process is initiated. It is worth using feature selection algorithms to raise the sensitivity and accuracy values.

Analysis of Brain Functional Changes in High-Frequency Repetitive Transcranial Magnetic Stimulation in Treatment-Resistant Depression

Repetitive transcranial magnetic stimulation (rTMS) is a treatment procedure that uses magnetic fields to stimulate nerve cells in the brain, and is associated with significant improvements in clinical symptoms of major depressive disorder (MDD). The effect of rTMS treatment on the brain can be evaluated by cordance, a quantitative electroencephalography (QEEG) method that extracts information from absolute and relative power of EEG spectra. In this study, to analyze brain functional changes, pre- and post-rTMS, QEEG data were collected from 6 frontal electrodes (Fp1, Fp2, F3, F4, F7, and F8) in 2 slow bands (delta and theta) for 55 MDD subjects. To examine brain changes, cordance scores were determined, using repeated-measures analysis of variance (ANOVA). High-frequency rTMS was associated with cordance decrease in left frontal and right prefrontal regions in both delta and theta for nonresponders; it was associated with cordance increase in all right and left frontal electrodes, except F8, for responders.

Ant Colony Optimization Based Feature Selection Method for QEEG Data Classification

OBJECTIVE

Many applications such as biomedical signals require selecting a subset of the input features in order to represent the whole set of features. A feature selection algorithm has recently been proposed as a new approach for feature subset selection.

METHODS

Feature selection process using ant colony optimization (ACO) for 6 channel pre-treatment electroencephalogram (EEG) data from theta and delta frequency bands is combined with back propagation neural network (BPNN) classification method for 147 major depressive disorder (MDD) subjects.

RESULTS

BPNN classified R subjects with 91.83% overall accuracy and 95.55% subjects detection sensitivity. Area under ROC curve (AUC) value after feature selection increased from 0.8531 to 0.911. The features selected by the optimization algorithm were Fp1, Fp2, F7, F8, F3 for theta frequency band and eliminated 7 features from 12 to 5 feature subset.

CONCLUSION

ACO feature selection algorithm improves the classification accuracy of BPNN. Using other feature selection algorithms or classifiers to compare the performance for each approach is important to underline the validity and versatility of the designed combination.

Evidence-based guidelines on the therapeutic use of repetitive transcranial magnetic stimulation (rTMS)

A group of European experts was commissioned to establish guidelines on the therapeutic use of repetitive transcranial magnetic stimulation (rTMS) from evidence published up until March 2014, regarding pain, movement disorders, stroke, amyotrophic lateral sclerosis, multiple sclerosis, epilepsy, consciousness disorders, tinnitus, depression, anxiety disorders, obsessive-compulsive disorder, schizophrenia, craving/addiction, and conversion. Despite unavoidable inhomogeneities, there is a sufficient body of evidence to accept with level A (definite efficacy) the analgesic effect of high-frequency (HF) rTMS of the primary motor cortex (M1) contralateral to the pain and the antidepressant effect of HF-rTMS of the left dorsolateral prefrontal cortex (DLPFC). A Level B recommendation (probable efficacy) is proposed for the antidepressant effect of low-frequency (LF) rTMS of the right DLPFC, HF-rTMS of the left DLPFC for the negative symptoms of schizophrenia, and LF-rTMS of contralesional M1 in chronic motor stroke. The effects of rTMS in a number of indications reach level C (possible efficacy), including LF-rTMS of the left temporoparietal cortex in tinnitus and auditory hallucinations. It remains to determine how to optimize rTMS protocols and techniques to give them relevance in routine clinical practice. In addition, professionals carrying out rTMS protocols should undergo rigorous training to ensure the quality of the technical realization, guarantee the proper care of patients, and maximize the chances of success. Under these conditions, the therapeutic use of rTMS should be able to develop in the coming years.

Biological markers in noninvasive brain stimulation trials in major depressive disorder: a systematic review

OBJECTIVES

The therapeutic effects of transcranial magnetic stimulation (TMS) and transcranial direct current stimulation in patients with major depression have shown promising results; however, there is a lack of mechanistic studies using biological markers (BMs) as an outcome. Therefore, our aim was to review noninvasive brain stimulation trials in depression using BMs.

METHODS

The following databases were used for our systematic review: MEDLINE, Web of Science, Cochrane, and SCIELO. We examined articles published before November 2012 that used TMS and transcranial direct current stimulation as an intervention for depression and had BM as an outcome measure. The search was limited to human studies written in English.

RESULTS

Of 1234 potential articles, 52 articles were included. Only studies using TMS were found. Biological markers included immune and endocrine serum markers, neuroimaging techniques, and electrophysiological outcomes. In 12 articles (21.4%), end point BM measurements were not significantly associated with clinical outcomes. All studies reached significant results in the main clinical rating scales. Biological marker outcomes were used as predictors of response, to understand mechanisms of TMS, and as a surrogate of safety.

CONCLUSIONS

Functional magnetic resonance imaging, single-photon emission computed tomography, positron emission tomography, magnetic resonance spectroscopy, cortical excitability, and brain-derived neurotrophic factor consistently showed positive results. Brain-derived neurotrophic factor was the best predictor of patients' likeliness to respond. These initial results are promising; however, all studies investigating BMs are small, used heterogeneous samples, and did not take into account confounders such as age, sex, or family history. Based on our findings, we recommend further studies to validate BMs in noninvasive brain stimulation trials in MDD.

Prefrontal dysfunction in remitted depression at work reinstatement using near-infrared spectroscopy

A long-term and/or recurrent sickness absence from work due to depression has been an important health problem in industrial countries. In addition, previous sick leave is a risk factor of recurrence. However, many characteristics, especially biological aspects, have not been investigated in remitted depressive patients who were ready to return to work from sickness absence. Therefore, the purpose of this study is to clarify the pathophysiological characteristics of patients who were at risk for recurrence of sickness absence. We recruited 21 patients and 16 healthy control subjects. All patients were ready to return to work within one month from long-term sickness absence. All subjects were examined for prefrontal function represented by oxyHb changes during the verbal fluency task (VFT) and the Stroop task using near-infrared spectroscopy. Suppressed prefrontal reaction during the VFT and increased prefrontal reaction during the Stroop task were observed in the patient group compared with the control group. Significantly lengthened reaction time was observed in the incongruent condition in the patient group during the Stroop task. Depressive patients showed impaired executive function measured by the Stroop task and had prefrontal dysfunction despite clinical remission. Residual prefrontal dysfunction may be one biological reason for repetitive sickness absence.

Changes of oscillatory brain activity induced by repetitive transcranial magnetic stimulation of the left dorsolateral prefrontal cortex in healthy subjects

Repetitive transcranial magnetic stimulation (rTMS) modulates brain activity in different ways according to the stimulation parameters. Although the after-effects of rTMS over motor cortex are well documented in healthy individuals, less is known about the stimulation of dorso-lateral prefrontal cortex (DLPFC). Here, we studied in 20 healthy subjects how cortical oscillations are modulated by four different active rTMS protocols (1Hz, 10Hz, continuous and intermittent theta bursts - cTBS and iTBS) of the left DLPFC, and by a sham protocol used as a control condition, by comparing the spectral power of pre- and post-rTMS electroencephalographic (EEG) recordings of 15min duration. EEG spectrum was estimated with the fast Fourier transform (FFT) and partitioned using the common physiological frequency bands: delta (1-4Hz), theta (3.5-7Hz), alpha (7.5-13Hz), low beta (14-22Hz), high beta (22-30Hz) and gamma (30-45Hz). Statistical analyses of EEG changes induced by rTMS were computed with Statistical Parametric Mapping (SPM) for EEG, in every frequency band, at the scalp level and at the cortex level. We found for every active protocol a significant decrease of delta and theta power on left prefrontal electrodes, mainly localised in the left DLPFC. In higher frequency bands (beta and gamma), the decrease of power in the DLPFC was also observed contralaterally. Protocol-specific amplitude effects were found in the prefrontal cortex bilaterally in all frequency bands, but also in parietal and temporal regions in low EEG frequencies. In high frequencies, EEG power in the prefrontal cortex increased after rTMS for 10Hz and iTBS protocols, but this effect did not survive the comparison to Sham responses. Because large delta and theta activity is usually associated with cortical inhibition, observed rTMS-induced EEG changes in low frequencies suggest that rTMS of DLPFC transiently decreases local cortical inhibition. Importantly, local responses take place in association with other unknown mechanisms that modulate inter-hemispheric connectivity between homologous regions, resulting in the increase or decrease of fast activity in each prefrontal lobe, depending on the stimulation protocol. Only decreases of fast activity following active rTMS could be detected as significant when compared to Sham stimulation.

Maintenance transcranial magnetic stimulation reduces depression relapse: a propensity-adjusted analysis

BACKGROUND

The effectiveness of repetitive transcranial magnetic stimulation (TMS) is well established while studies of maintenance TMS are lacking. We aim here to determine whether maintenance is associated to a decrease in the relapse rate of depression, following successful acute treatment.

METHODS

We enrolled 59 consecutive patients with pharmacoresistant depression who have responded (>50% decrease in symptom severity) up to 6 weeks of acute TMS treatment. These patients received either 20 weeks of maintenance TMS (n=37) or no additional TMS treatment (n=22). We performed propensity adjusted-analysis to examine the association between the relapse rate over this 20-week period and maintenance TMS. Propensity analysis eliminated differences in baseline characteristics between patient with and without maintenance TMS and approximated the conditions of random site-of-treatment assignment.

RESULTS

At 20 weeks, relapse rate was significantly different between the two groups (p=0.004, propensity analysis): 14 patients in the maintenance TMS group (37.8%) vs. 18 in the non-maintenance TMS group (81.8%), with an adjusted Hazard Ratio (HR)=0.288 (0.124-0.669).

CONCLUSIONS

Maintenance TMS was associated with a significantly lower relapse rate in patients with pharmacoresistant depression in routine practice among responders.

The value of ethyl cysteinate dimer single photon emission computed tomography in predicting antidepressant treatment response in patients with major depression

OBJECTIVE

The purpose of this study is to examine whether the reversal of compromised regional cerebral blood flow (rCBF) in older patients with major depressive disorder (MDD) is dependent on specific parameters of selective serotonin reuptake inhibitor (SSRI) treatment and to examine the efficacy of such treatment.

METHODS

Forty-five patients with moderate MDD were studied following 8 weeks of treatment with SSRIs. Twelve patients displayed a positive response to SSRIs, whereas 33 patients did not respond to SSRI treatment. A comparison group of 30 healthy volunteers was also studied. The age of all participants was greater than 50 years. Age, gender, and the Hamilton Rating Scale for Depression scores were examined. The rCBF was assessed using 99mTc-ethyl cysteinate dimer single photon emission computed tomography after SSRI treatment.

RESULTS

The rCBF levels in the right middle frontal cortex in non-responsive MDD patients were lower compared with responsive MDD patients. Compared with healthy controls, non-responders had significantly lower rCBF levels in the bilateral middle frontal cortex and insula and had significantly higher rCBF levels in the bilateral inferior frontal cortex and left middle temporal cortex. Compared with healthy controls, responders had significantly higher rCBF levels in the left inferior frontal, middle temporal, precentral, and fusiform gyrus. We found no changes in single photon emission computed tomography between pre-treatment and post-treatment stages for the responders to SSRI treatment.

CONCLUSION

Hypoperfusion in older, non-responsive MDD patients was primarily localized in the middle frontal cortex. It is possible that the responders to SSRI treatment at baseline already displayed higher rCBF values in the frontal regions.

Gene expression analysis of novel genes in the prefrontal cortex of major depressive disorder subjects

Dysregulation of the glutamatergic system has been implicated not only in the treatment of major depressive disorder (MDD), but also in the excitotoxic effects of stress and anxiety on the prefrontal cortex, which may precede the onset of a depressive episode. Our previous studies demonstrate marked deficits in prominent postsynaptic proteins involved in glutamate neurotransmission in the prefrontal cortex (PFC), Brodmann's area 10 (BA 10) from subjects diagnosed with major depressive disorder (MDD). In the same group of subjects we have identified deficits in expression and phosphorylation level of key components of the mammalian target of rapamycin (mTOR) signaling pathway, known to regulate translation initiation. Based on our previous findings, we have postulated that glutamate-dependent dysregulation of mTOR-initiated protein synthesis in the PFC may underlie the pathology of MDD. The aim of this study was to use the NanoString nCounter System to perform analysis of genes coding for glutamate transporters, glutamate metabolizing enzymes, neurotrophic factors and other intracellular signaling markers involved in glutamate signaling that were not previously investigated by our group in the PFC BA 10 from subjects with MDD. We have analyzed a total of 200 genes from 16 subjects with MDD and 16 healthy controls. These are part of the same cohort used in our previous studies. Setting our cutoff p-value≤0.01, marked upregulation of genes coding for mitochondrial glutamate carrier (GC1; p=0.0015), neuropilin 1 (NRP-1; p=0.0019), glutamate receptor ionotropic N-methyl-d-aspartate-associated protein 1 (GRINA; p=0.0060), and fibroblast growth factor receptor 1 (FGFR-1; p=0.010) was identified. No significant differences in expression of the remaining 196 genes were observed between MDD subjects and controls. While upregulation of FGFR-1 has been previously shown in MDD; abnormalities in GC-1, GRINA, and NRP-1 have not been reported. Therefore, this postmortem study identifies GC1, GRINA, and NRP-1 as novel factors associated with MDD; however, future studies will be needed to address the significance of these genes in the pathophysiology of depression and antidepressant activity.

Equivalent brain SPECT perfusion changes underlying therapeutic efficiency in pharmacoresistant depression using either high-frequency left or low-frequency right prefrontal rTMS

BACKGROUND

Functional neuroimaging studies have suggested similar mechanisms underlying antidepressant effects of distinct therapeutics.

OBJECTIVE

This study aimed to determine and compare functional brain patterns underlying the antidepressant response of 2 distinct protocols of repetitive transcranial magnetic stimulation (rTMS).

METHODS

99mTc-ECD SPECT was performed before and after rTMS of dorsolateral prefrontal cortex in 61 drug-resistant right-handed patients with major depression, using high frequency (10Hz) left-side stimulation in 33 patients, and low frequency (1Hz) right-side stimulation in 28 patients. Efficiency of rTMS response was defined as at least 50% reduction of the baseline Beck Depression Inventory score. We compared the whole-brain voxel-based brain SPECT changes in perfusion after rTMS, between responders and non-responders in the whole sample (p<0.005, uncorrected), and separately in the subgroup of patients with left- and right-stimulation.

RESULTS

Before rTMS, the left- and right-prefrontal stimulation groups did not differ from clinical data and brain SPECT perfusion. rTMS efficiency (evaluated on % of responders) was statistically equivalent in the two groups of patients. In the whole-group of responder patients, a perfusion decrease was found after rTMS, in comparison to non-responders, within the left perirhinal cortex (BA35, BA36). This result was secondarily confirmed separately in the two subgroups, i.e. after either left stimulation (p=0.017) or right stimulation (p<0.001), without significant perfusion differences between these two subgroups.

CONCLUSIONS

These data show that distinct successful rTMS protocols induce equivalent brain functional changes associated to antidepressive efficiency, consisting to a remote brain limbic activity decrease within the left perirhinal cortex. However, these results will have to be confirmed in a double-blind randomized trial using a sham control group.

Schizophrenia with preserved insight is associated with increased perfusion of the precuneus

BACKGROUND

Preserved insight into illness has been suggested to be predictive of outcome in patients with schizophrenia. We aimed to investigate the functional substrate underlying preserved insight in these patients.

METHODS

We recruited patients with paranoid schizophrenia and healthy controls matched for age and sex. Patients were grouped according to preserved or impaired insight into illness using the Scale to assess Unawareness of Mental Disorder (SUMD). Whole-brain technetium-99m ethyl cysteinate dimer single photon emission computed tomography regional cerebral blood flow was compared at the voxel level between the 2 groups using a statistical parametric map (voxel-level significance of p < 0.001, uncorrected; cluster level significance of p < 0.05, uncorrected).

RESULTS

We enrolled 31 right-handed patients with schizophrenia and 18 controls in our study. Twenty-one (67.7%) patients had preserved insight. The 2 groups did not differ significantly in demographic and clinical characteristics or in treatment. Compared with controls, the whole group of patients showed bilateral frontotemporal hypoperfusions, with no statistical difference between patients with preserved or impaired insight for these areas. Patients with preserved insight showed significantly increased perfusion of the bilateral precuneus relative to those with impaired insight.

LIMITATIONS

Patients with subtypes other than paranoid schizophrenia have to be investigated to assess whether involvement of the precuneus in patients with preserved insight can be identified across the full spectrum of subtypes and symptoms of schizophrenia. Moreover, our study concerned only the central dimension (awareness of mental disorder) of 1 scale (SUMD); other dimensions of insight could be studied.

CONCLUSION

Our results show that schizophrenia with preserved insight is associated with greater perfusion of the precuneus, a brain area known to be involved in self- consciousness, suggesting a compensatory mechanism of fronto-temporal impairment.

Improvement of health-related quality of life in depression after transcranial magnetic stimulation in a naturalistic trial is associated with decreased perfusion in precuneus

Background

Assessing Health-related Quality of life (HRQoL) is necessary to evaluate care and treatments provided to patients with major depressive disorder (MDD), in addition to the traditional assessment of clinical outcomes. However, HRQoL remains under-utilized to assess the effectiveness of repetitive transcranial magnetic stimulation (rTMS) in research or in a routine clinical setting. The primary objective of this exploratory study on MDD was to investigate the impact of low-frequency rTMS on HRQoL using the SF-36 questionnaire. A secondary objective was to study the functional neural substrate underlying HRQoL changes using neuroimaging.

Methods

Fifteen right-handed patients who met DSM-IV criteria for MDD participated in the study. HRQoL was assessed using the SF-36, and regional cerebral blood (rCBF) flow using 99mTc-ECD-SPECT. Voxel based correlation was searched between concomitant changes in rCBF and in HRQoL after rTMS.

Results

Role-Physical Problems dimension showed a statistical significant improvement of 73.2% (p = 0.001) and an effect size (Cohen’s d) of 0.43, indicating moderate effect. Five SF-36 dimension scores and the two composite scores showed effect sizes ranged from 0.28 to 0.43. Improvement of Mental Composite Score (MCS)-SF-36 after rTMS was correlated with a concomitant decrease of precuneus perfusion (p < 0.001). Post-hoc analyses confirmed that decreased perfusion in precuneus was correlated with improvement of HRQoL, especially for MCS (r = −0.71; p < 0.001), Mental Health (r = −0.81; p < 0.001) and Social Functioning (r = −0.57; p = 0.026) dimensions.

Conclusions

This study suggests low-frequency rTMS can improve HRQoL, through its role-physical problems dimension, in patients with MDD. This improvement is associated with a decreased perfusion of the precuneus, a brain area involved in self-focus and self-processing, arguing for a neural substrate to the impact of rTMS on HRQoL.

Functional involvement of superior temporal sulcus in quality of life of patients with schizophrenia

The aim of this study was to investigate the neural substrate underlying quality of life (QoL) in patients with schizophrenia. Thirty-one right-handed patients were included. Patients were grouped according to 'high' and 'low' QoL levels. Whole-brain single photon emission computed tomography (SPECT) with (99m)Tc-labeled ethylcysteinate dimer ((99m)Tc-ECD), for the measurement of voxel-based regional cerebral blood flow (rCBF), was used to compare these two groups with Statistical Parametric Mapping. Correlations of rCBF with QoL scores were secondarily explored. Nineteen of the 31 patients had a high QoL level. There was no significant difference in demographic and clinical characteristics between patients with high and low QoL levels. In comparison to patients with low QoL, those with high QoL exhibited significant bilateral temporal hypoperfusions, primarily in the superior temporal sulcus (STS). In the total group of patients, perfusion in the left STS was negatively correlated with psychological well-being, self-esteem, and sentimental life, as well as with the global index of the questionnaire. This study shows that perfusion of the STS, a brain area thought to contribute to self/other awareness and metacognition, is involved in the functional substrate underlying QoL. Our findings contribute to clarifying the scientific foundation required for a better clinical use of QoL questionnaires by suggesting that the recognition of illness-related impairment is associated with alteration of QoL.

Parieto-temporal alpha EEG band power at baseline as a predictor of antidepressant treatment response with repetitive Transcranial Magnetic Stimulation: a preliminary study

BACKGROUND

The aim of this preliminary study was to determine the predictive value of absolute alpha band power measured during the rest EEG eyes closed task for responses to 20 sessions of high frequency repetitive transcranial stimulation (rTMS) in the left dorsolateral prefrontal cortex in patients with pharmacoresistant major depressive episode.

METHODS

13 major depressive disorders (8 males) and 8 bipolar disorders (6 males) were included (mean age 58years). Spearman correlations between pretreatment alpha band power in height regions of analysis and absolute improvement in Beck Depression Inventory Short Form (ΔBDI-SF) were analyzed. The predictive value of alpha band power for classifying patients as responders and non-responders to rTMS was determined using Receiver Operating Characteristic (ROC) curve.

RESULTS

Spearman correlation analysis revealed that ΔBDI-SF correlated significantly and negatively with alpha band power on the right (r=-.673, p=.001) and left parieto-temporal regions (r=-.638, p=.002). The area under the ROC curve for the right parieto-temporal was .815, p=.0037. The cut-off point that maximized both sensitivity and specificity was 1.49μV. Sensitivity, specificity, positive and negative predictive values were 100, 66, 80, 100% respectively.

LIMITATIONS

The population was small and lacked homogeneity concerning affective disorders (unipolar and bipolar disorder). The use of a self-rating subjective scale (BDI-SF) to measure the severity of depression could be criticized.

CONCLUSIONS

Pretreatment alpha band power on parieto-temporal regions could be a predictor for response to rTMS in patients with homogenous demographic/clinical features. The association between electrical activity and the perfusion under each electrode need to be examined.