The multiple facets of treatment-resistant depression

Increased entrainment and decreased excitability predict efficacious treatment of closed-loop phase-locked rTMS for treatment-resistant depression

Transcranial magnetic stimulation (TMS) is an FDA-approved therapy for major depressive disorder (MDD), specifically for patients who have treatment-resistant depression (TRD). However, TMS produces response or remission in about 50% of patients but is ineffective for the other 50%. Limits on efficacy may be due to individual patient variability, but to date, there are no good biomarkers or measures of target engagement. In addition, TMS efficacy is typically not assessed until a six-week treatment ends, precluding the evaluation of intermediate improvements during the treatment duration. Here, we report on results using a closed-loop phase-locked repetitive TMS (rTMS) treatment that synchronizes the delivery of rTMS based on the timing of the pulses relative to a patient's individual electroencephalographic (EEG) prefrontal alpha oscillation informed by functional magnetic resonance imaging (fMRI). We find that, in responders, synchronized delivery of rTMS produces two systematic changes in brain dynamics. The first change is a decrease in global cortical excitability, and the second is an increase in the phase entrainment of cortical dynamics. These two effects predict clinical outcomes in the synchronized treatment group but not in an active-treatment unsynchronized control group. The systematic decrease in excitability and increase in entrainment correlated with treatment efficacy at the endpoint and intermediate weeks during the synchronized treatment. Specifically, we show that weekly tracking of these biomarkers allows for efficacy prediction and potential of dynamic adjustments through a treatment course, improving the overall response rates.

The prevalence and economic burden of treatment-resistant depression in Thailand

BACKGROUND

The objectives of this study were to investigate the proportion of treatment-resistant depression (TRD) among patients with diagnosed major depressive disorder (MDD) and undergoing antidepressant treatment, to estimate the economic cost of MDD, TRD, and non-treatment-resistant depression (non-TRD), and to examine the differences between TRD and non-TRD MDD in a Thai public tertiary hospital.

METHODS

This was a combined study between retrospective review of medical records and a cross-sectional survey. The sample size was 500 dyads of antidepressant-treated MDD patients and their unpaid caregivers. MDD patients' medical records, the concept of healthcare resource utilization, the Work Productivity and Activity Impairment Questionnaire: depression and mood & mental state versions (WPAI: D, MM), the Class Impairment Questionnaire (CIQ), and the Family Experiences Interview Schedule (FEIS) were applied as the tools of the study. Pearson Chi's square, Fisher's Exact test, and independent T-test were employed for statistical analysis.

RESULTS

The proportion of TRD was 19.6% among antidepressant-treated MDD patients in a Thai tertiary public hospital. The results of the study indicated that several factors showed a statistically significant association with TRD criteria. These factors included younger age of MDD patients, a younger age of onset of MDD, lower body mass index (BMI), a history of suicide attempts and self-harm, as well as frequent smoking behavior. The annualized economic cost of TRD was 276,059.97 baht per person ($7,668.33), which was significantly higher than that of cost of non-TRD (173,487.04 baht or $4,819.08). The aggregated economic costs of MDD were 96.8 million baht annually ($2.69 M) if calculated from 500 MDD patients and unpaid caregivers. This contributed to the economic cost of TRD 27.05 million baht (98 respondents) and the economic cost of non-TRD 69.74 million baht (402 respondents).

CONCLUSIONS

The economic burden associated with TRD was significantly higher compared to non-TRD among antidepressant-treated MDD patients. Specifically, both direct medical costs and indirect costs were notably elevated in the TRD group.

Structural and functional features of treatment-resistant depression: A systematic review and exploratory coordinate-based meta-analysis of neuroimaging studies

OBJECTIVES

A third of people suffering from major depressive disorder do not experience a significant improvement in their symptoms even after adequate treatment with two different antidepressant medications. This common condition, termed treatment-resistant depression (TRD), severely affects the quality of life of millions of people worldwide, causing long-lasting interpersonal problems and social costs. Given its epidemiological and clinical relevance and the little consensus on whether the neurobiological underpinnings of TRD differ from treatment-sensitive depression (TSD), we sought to highlight the convergent morphometric and functional neuroimaging correlates of TRD.

METHODS

We systematically reviewed the published literature on structural and resting-state functional neuroimaging of TRD compared to TSD and healthy controls (HC) and performed exploratory coordinate-based meta-analyses (CBMA) of significant results separately for each modality and multimodally ("all-effects"). CBMAs were also performed for each direction and combining both directions of group contrasts.

RESULTS

Out of the initial 1929 studies, only eight involving 555 participants (189 patients with TRD, 156 with TSD, and 210 HC) were included. In all-effects CBMA, precentral/superior frontal gyrus showed a significant difference between TRD and HC. Functional and structural imaging meta-analyses did not yield statistically significant results. A marginally significant cluster of altered intrinsic activity was found between TRD and HC in the cerebellum/pons.

CONCLUSIONS

Frontal, cerebellar, and brainstem functions can be involved in the pathophysiology of TRD. However, the design and heterogeneity of the (scarce) published literature hinder the generalizability of the findings.

European Group for the Study of Resistant Depression (GSRD)--where have we gone so far: review of clinical and genetic findings

The primary objective of this review is to give an overview of the main findings of the European multicenter project "Patterns of Treatment Resistance and Switching Strategies in Affective Disorder", performed by the Group for the Study of Resistant Depression (GSRD). The aim was to study methodological issues, operational criteria, clinical characteristics, and genetic variables associated with treatment resistant depression (TRD), that is failure to reach response after at least two consecutive adequate antidepressant trials. The primary findings of clinical variables associated with treatment resistance include comorbid anxiety disorders as well as non-response to the first antidepressant received lifetime. Although there is a plethora of hints in textbooks that switching the mechanism of action should be obtained in case of nonresponse to one medication, the results of the GSRD challenge this notion by demonstrating in retrospective and prospective evaluations that staying on the same antidepressant mechanism of action for a longer time is more beneficial than switching, however, when switching is an option there is no benefit to switch across class. The GSRD candidate gene studies found that metabolism status according to cytochrome P450 gene polymorphisms may not be helpful to predict response and remission rates to antidepressants. Significant associations with MDD and antidepressant treatment response were found for COMT SNPs. Investigating the impact of COMT on suicidal behaviour, we found a significant association with suicide risk in MDD patients not responding to antidepressant treatment, but not in responders. Further significant associations with treatment response phenotypes were found with BDNF, 5HTR2A and CREB1. Additional investigated candidate genes were DTNBP1, 5HT1A, PTGS2, GRIK4 and GNB3.

Staging methods for treatment resistant depression. A systematic review

BACKGROUND

Treatment resistant depressant (TRD) is classified in different staging models, but these are not used routinely. We aimed to identify staging models for TRD and compare them regarding predictive utility and reliability.

METHODS

Systematic review of Pubmed, Embase and PsycINFO (1985-January 2010) without language limits, plus articles identified from reference lists of previous reviews. We excluded articles focusing on TRD treatment. We qualitatively summarized characteristics of the identified staging models, describing strengths and limitations for each model. If available, we reported results of validation studies.

RESULTS

From 950 retrieved articles five staging models were found; the Antidepressant Treatment History Form, Thase and Rush Model, European Staging Model, Massachusetts General Hospital Staging model and the Maudsley Staging Model (MSM). Six studies investigated the predictive utility (of four models). We observed an evolution from single antidepressant adequacy ratings, towards a multidimensional and more continuous scored staging model which also introduced TRD characteristics (severity and duration). The operationalization criteria improved; the scoring of different treatment strategies (between/within class switching and augmentation/combination) changed according to the existing evidence. Over time, efforts to validate models improved. The predictive utility was assessed best for the MSM.

LIMITATIONS

Few staging models existed; their reliability was hardly assessed.

CONCLUSIONS

Despite validation of the MSM, further investigation of the reliability and predictive utility of TRD staging models and additional disease characteristics is required. Correct staging of TRD might improve generalizability of results from clinical studies and improve delivery of care to TRD patients. We propose methods to validate staging models in TRD.

Lamotrigine augmentation strategy for patients with treatment-resistant depression

OBJECTIVE

To investigate if lamotrigine added to an antidepressant regimen reduces the symptoms of major depression in treatment-resistant patients.

INTRODUCTION

Charts were retrospectively reviewed for 34 patients (36-63 years of age) with major depressive disorder who received lamotrigine augmentation to the antidepressant regimen for treatment-resistant depression (TRD). Data collection occurred at baseline and at an average of 30 (Time 2), 78 (Time 3), 167 (Time 6), and 356 days (Time 12), thereafter, using a "Medication Visit by MD" scale for collection of target symptom data at each timepoint.

RESULTS

Following the addition of lamotrigine to the antidepressant regimen (mean dose of 43, 63, and 113 mg/day for Time 3, Time 6, and Time 12, respectively), a statistically significant reduction of scores was shown as early as Time 2 for target symptoms of depressed mood, loss of interest, anxiety, irritability, (low) energy, and cognitive impairment. The difference from baseline remained statistically significant at Time 3, Time 6, and Time 12 (with the exception of irritability, which was not statistically significant at Time 6). "Patient's response" also reflected statistically significant improvement at each time period compared with baseline. The most common side effect reported and reason for discontinuation was tiredness.

DISCUSSION

Because TRD is a clinical condition that can present with severe and disabling symptoms, many clinicians are faced with an urgent need to find relief for their patients. Trying to achieve symptom improvement in a timely manner during a medication change can be challenging and difficult. This can be managed by an augmentation strategy using a psychotropic add-on to an existing medication regimen. Our results show the benefits of lamotrigine augmentation to an antidepressant regimen. Prospective, controlled clinical trials with larger sample size are needed to confirm our results.

CONCLUSION

In this retrospective chart review, augmentation with lamotrigine was a tolerable and efficacious strategy for treating patients with TRD.