Treatment-resistant depression: therapeutic trends, challenges, and future directions

New use for an old drug: oral ketamine for treatment-resistant depression

Treatment-resistant depression (TRD) is a disabling disorder that can interfere with a patient's capacity to understand and participate in medical care and thus negatively impact individual morbidity and mortality. Hospitalised patients with TRD may require rapid alleviation of severe symptomatology, particularly when suicidal or if unable to participate in care decisions. Ketamine is well known for its anaesthetic effects and its use as a 'street' drug; however, its action as an N-methyl-D-aspartate receptor antagonist makes ketamine a potential therapy for TRD. The majority of studies investigating ketamine for TRD have used intravenous drug delivery, demonstrating benefit for rapid alleviation and sustained response of depression symptoms. Oral ketamine for urgent alleviation of TRD symptoms is less reported. We describe rapid alleviation of severe TRD with oral ketamine in a severely ill postoperative hospitalised patient, and review the current literature on 'off-label' use of ketamine for treatment of refractory depression.

Socio-demographic and clinical predictors of non-response/non-remission in treatment resistant depressed patients: A systematic review

Up to one third of patients adequately treated for Major Depressive Disorder (MDD) do not respond to multiple interventions. Many studies investigated predictors in MDD outcome, but no study focused on predictors of non-response or non-remission to antidepressants in subjects with treatment resistant depression (TRD). The present study aimed to evaluate possible socio-demographic and clinical predictors of non-response and non-remission in MDD patients who failed to benefit from at least one antidepressant trial. A total of 51 papers were included. A number of severity indicators, such as longer duration of depressive episode, moderate-high suicidal risk, anxious comorbidity, higher number of hospitalizations and higher dosage of antidepressants, were associated with non-response as well as age. Interestingly, severity of illness, as well as comorbid personality disorders and anxiety symptoms, had also a predictive value in non-remission with the addition of marital status. Considering limitations, selected studies were observational or randomized non controlled/controlled trials and different TRD definitions and outcome measures were used. Overall, predictors of outcome were similar to MDD, but specific socio-demographic and clinical factors should be considered in clinical practice to formulate a more focused treatment in TRD patients.

Neuroinflammation at the interface of depression and cardiovascular disease: Evidence from rodent models of social stress

A large body of evidence has emerged linking stressful experiences, particularly from one's social environment, with psychiatric disorders. However, vast individual differences emerge in susceptibility to developing stress-related pathology which may be due to distinct differences in the inflammatory response to social stress. Furthermore, depression is an independent risk factor for cardiovascular disease, another inflammatory-related disease, and results in increased mortality in depressed patients. This review is focused on discussing evidence for stress exposure resulting in persistent or sensitized inflammation in one individual while this response is lacking in others. Particular focus will be directed towards reviewing the literature underlying the impact that neuroinflammation has on neurotransmitters and neuropeptides that could be involved in the pathogenesis of comorbid depression and cardiovascular disease. Finally, the theme throughout the review will be to explore the notion that stress-induced inflammation is a key player in the high rate of comorbidity between psychosocial disorders and cardiovascular disease.

Modeling psychiatric disorders with patient-derived iPSCs

Psychiatric disorders are heterogeneous disorders characterized by complex genetics, variable symptomatology, and anatomically distributed pathology, all of which present challenges for effective treatment. Current treatments are often blunt tools used to ameliorate the most severe symptoms, often at the risk of disrupting functional neural systems, thus there is a pressing need to develop rational therapeutics. Induced pluripotent stem cells (iPSCs) reprogrammed from patient somatic cells offer an unprecedented opportunity to recapitulate both normal and pathologic human tissue and organ development, and provides new approaches for understanding disease mechanisms and for drug discovery with higher predictability of their effects in humans. Here we review recent progress and challenges in using human iPSCs for modeling neuropsychiatric disorders and developing novel therapeutic strategies.

Is off-label repeat prescription of ketamine as a rapid antidepressant safe? Controversies, ethical concerns, and legal implications

Background

Depressive disorders are a common form of psychiatric illness and cause significant disability. Regulation authorities, the medical profession and the public require high safety standards for antidepressants to protect vulnerable psychiatric patients. Ketamine is a dissociative anaesthetic and a derivative of a hallucinogen (phencyclidine). Its abuse is a major worldwide public health problem. Ketamine is a scheduled drug and its usage is restricted due to its abuse liability. Recent clinical trials have reported that ketamine use led to rapid antidepressant effects in patients suffering from treatment-resistant depression. However, various flaws in study designs, and possible biased reporting of results, may have influenced those findings. Further analyses of ketamine use are needed to ensure patient safety.

Discussion

The use of ketamine in research and treatment of depressive disorders is controversial. Recently, mental health professionals raised ethical concerns about an ongoing ketamine trial in the UK. Also, a Canadian agency reviewed the existing evidence and did not recommend prescribing ketamine to treat depressive disorders. Findings obtained from tightly controlled research settings cannot be easily translated to clinical practice as substance abuse is commonly comorbid with depressive disorders. An effective antidepressant should reduce severity of depressive symptoms without liability problems. Although the US FDA has not approved the use of ketamine to treat depressive disorders, some psychiatrists offer off-label repeat prescription of ketamine. Prescribing ketamine for treating depressive disorders requires substantial empirical evidence. Clinicians should also consider research findings on ketamine abuse. Depressive disorders can be chronic conditions and the current evidence does not rule out the risk of substance abuse after repeat prescription of ketamine. Off-label ketamine use in treating depressive disorders may breach ethical and moral standards, especially in countries seriously affected by ketamine abuse. This article presents two real-world clinical vignettes which highlight ethical principles and theories, including autonomy, nonmaleficience, fidelity and consequentialism, as related to off-label ketamine use.

Conclusion

We urge clinicians to minimise the risk of harming patients by considering the empirical evidence on ketamine properties and attempting all standard antidepressant therapies before considering the off-label use of ketamine.

Efficacy and tolerability of switching therapy to vortioxetine versus other antidepressants in patients with major depressive disorder

OBJECTIVES

To assess the relative efficacy and tolerability of vortioxetine against different antidepressant monotherapies in patients with major depressive disorder (MDD) with inadequate response to selective serotonin reuptake inhibitor (SSRI) or serotonin-norepinephrine reuptake inhibitor (SNRI) therapy.

METHODS

A systematic search was conducted for monotherapy studies in patients with MDD with inadequate response to first-line therapy. Treatments included SSRIs, SNRIs, and other antidepressants. Identified studies underwent a three-stage screening/data extraction process and critical appraisal. Adjusted indirect treatment comparisons (ITCs) on systematic literature review outputs were made using Bucher's method, comparing remission rates and withdrawal rates due to adverse events (AEs).

RESULTS

Of 27 studies meeting the inclusion criteria, a few studies were of high quality according to the National Institute of Health and Care Excellence checklist. Three studies contributed to an evidence network for quantitative assessment comparing vortioxetine with agomelatine, sertraline, venlafaxine XR, and bupropion SR. Vortioxetine had a statistically significantly higher remission rate than agomelatine (risk difference [RD]: -11.0% [95% CI: -19.4; -2.6]), and numerically higher remission rates than sertraline (RD: -14.4% [95% CI: -29.9; 1.1]), venlafaxine (RD: -7.20% [95% CI: -24.3; 9.9]), and bupropion (RD: -10.70% [95% CI: -27.8; 6.4]). Withdrawal rates due to AEs were statistically significantly lower for vortioxetine than sertraline (RD: 12.1% [95% CI: 3.1; 21.1]), venlafaxine XR (RD: 12.3% [95% CI: 0.8; 23.8]), and bupropion SR (RD: 18.3% [95% CI: 6.4; 30.1]).

CONCLUSIONS

The current systematic literature review found a few high quality switch studies assessing monotherapies in patients with MDD with inadequate response to SSRI/SNRIs. ITCs indicated that switching to vortioxetine leads to numerically higher remission rates compared with other antidepressants. Vortioxetine is a well tolerated treatment, showing statistically lower withdrawal rates due to AEs compared with other antidepressants. Vortioxetine is a relevant therapeutic alternative in patients experiencing inadequate response to prior SSRI or SNRI therapy.

The role of methylphenidate in depression

Introduction

Depression is a burdening disease state where up to 30% of individuals do not respond to first-line treatment. Adjunctive use of psychostimulants has been investigated for the treatment of depression in patient populations, including those with treatment-resistant depression or terminal illness. The purpose of this paper is to present a review of the literature on the efficacy of using methylphenidate to manage depression.

Methods

A search was conducted in PubMed, Ovid/MEDLINE, and PsychINFO using the following key words: psychostimulants, stimulants, methylphenidate, alternative therapy, depression, and major depressive disorder. All reports included were published before June 30, 2015.

Results

For this review 10 reports, including randomized controlled, case series, and retrospective chart review studies, were identified and assessed. Patient populations studied included patients with treatment-resistant depression, patients with terminal illness, geriatric patients, and patients with miscellaneous indications, such as history of stroke and human immunodeficiency virus (HIV), or acquired immune deficiency syndrome (AIDS). For treatment-resistant depression, treatment differences for fatigue and apathy in favor of methylphenidate were found, but no difference was found for response rates in depression. Additionally, in palliative care and hospice patients, methylphenidate was found to improve fatigue and depressive symptoms. Patients with other conditions (poststroke and HIV patients) achieved some relief of depressive symptoms.

Conclusion

The efficacy data for methylphenidate in depression are limited, with inconsistent results in specific patient populations that limit external validity. At this time, it should not be recommended as first-line treatment in depression. Future research should be developed focusing on long-term safety and efficacy in nonspecialized patient populations.

GRIK4 polymorphism and its association with antidepressant response in depressed patients: a meta-analysis

AIM

This study aimed to evaluate the relationship between a human GRIK4 gene polymorphism (rs1954787) and responsiveness to antidepressant treatment in depressed patients.

METHODS

A meta-analysis was carried out on five studies. Pooled odds ratios (ORs), 95% CIs and a χ(2) test measuring heterogeneity were calculated. A test of publication bias was also conducted.

RESULTS

Alleles and genotypes from a total of 2169 depressed patients were analyzed. The results showed that the C allele appeared more frequently than the T allele in responders to treatment (OR: 1.22; 95% CI: 1.035-1.445; z = 2.36; p = 0.018). Similarly, CC homozygotes were more likely than TT homozygotes to respond to treatment (OR: 1.45; 95% CI: 1.107-1.913; z = 2.69; p = 0.007). No evidence of publication bias was detected.

CONCLUSION

Subjects possessing the C allele or CC genotype of the GRIK4 polymorphism rs1954787 are more likely to respond to antidepressant treatment relative to subjects harboring the T allele and TT genotype. Additional replication of this result is required before this association can be considered definitive, after which it may become possible to employ this marker in conjunction with other known predictors in order to anticipate the outcomes of treatment with antidepressant medications.

Pharmacologic approaches to treatment resistant depression: Evidences and personal experience

AIM: To review evidence supporting pharmacological treatments for treatment-resistant depression (TRD) and to discuss them according to personal clinical experience.

METHODS: Original studies, clinical trials, systematic reviews, and meta-analyses addressing pharmacological treatment for TRD in adult patients published from 1990 to 2013 were identified by data base queries (PubMed, Google Scholar e Quertle Searches) using terms: “treatment resistant depression”, “treatment refractory depression”, “partial response depression”, “non responder depression”, “optimization strategy”, “switching strategy”, “combination strategy”, “augmentation strategy”, selective serotonin reuptake inhibitors antidepressants (SSRI), tricyclic antidepressants (TCA), serotonin norepinephrine reuptake inhibitors antidepressants, mirtazapine, mianserine, bupropione, monoamine oxidase inhibitor antidepressant (MAOI), lithium, thyroid hormones, second generation antipsychotics (SGA), dopamine agonists, lamotrigine, psychostimulants, dextromethorphan, dextrorphan, ketamine, omega-3 fatty acids, S-adenosil-L-metionine, methylfolat, pindolol, sex steroids, glucocorticoid agents. Other citations of interest were further identified from references reported in the accessed articles. Selected publications were grouped by treatment strategy: (1) switching from an ineffective antidepressant (AD) to a new AD from a similar or different class; (2) combining the current AD regimen with a second AD from a different class; and (3) augmenting the current AD regimen with a second agent not thought to be an antidepressant itself.

RESULTS: Switching from a TCA to another TCA provides only a modest advantage (response rate 9%-27%), while switching from a SSRI to another SSRI is more advantageous (response rate up to 75%). Evidence supports the usefulness of switching from SSRI to venlafaxine (5 positive trials out 6), TCA (2 positive trials out 3), and MAOI (2 positive trials out 2) but not from SSRI to bupropione, duloxetine and mirtazapine. Three reviews demonstrated that the benefits of intra- and cross-class switch do not significantly differ. Data on combination strategy are controversial regarding TCA-SSRI combination (positive results in old studies, negative in more recent study) and bupropion-SSRI combination (three open series studies but not three controlled trails support the useful of this combination) and positive regard mirtazapine (or its analogue mianserine) combination with ADs of different classes. As regards the augmentation strategy, available evidences supported the efficacy of TCA augmentation with lithium salts and thyroid hormone (T3), but are conflicting regard the SSRI augmentation with these two drugs (1 positive trial out of 4 for lithium and 3 out of 5 for thyroid hormone). Double-blind controlled studies showed the efficacy of AD augmentation with aripiprazole (5 positive trials out 5), quetiapine (3 positive trials out 3) and, at less extent, of fluoxetine augmentation with olanzapine (3 positive trials out 6), so these drugs received the FDA indication for the acute treatment of TRD. Results on AD augmentation with risperidone are conflicting (2 short term positive trials, 1 short-term and 1 long-term negative trials). Case series and open-label trials showed that AD augmentation with pramipexole or ropinirole, two dopamine agonists, could be an effective treatment for TRD (response rate to pramipexole 48%-74%, to ropinirole 40%-44%) although one recent double-blind placebo-controlled study does not support the superiority of pramipexole over placebo. Evidences do not justify the use of psychostimulants, omega-3 fatty acids, S-adenosil-L-metionine, methylfolate, pindolol, lamotrigine, and sex hormone as AD augmentation for TRD. Combining the available evidences with our experience we suggest treating non-responders to one SSRI bupropion or mirtazapine trial by switching to venlafaxine, and non-responders to one venlafaxine trial by switching to a TCA or, if TCA are not tolerated, combining mirtazapine with SSRI or venlafaxine. In non-responders to two or more ADs (including at least one TCA if tolerated) current AD regimen could be augmented with lithium salts (mainly in patients with bipolar depression or suicidality), SGAs (mostly aripiprazole) or DA-agonists (mostly pramipexole). In patients with severe TRD, i.e., non-responders to combination and augmentation strategies as well as to electroconvulsive therapy if workable, we suggest to try a combination plus augmentation strategy.

CONCLUSION: Our study identifies alternative effective treatment strategies for TRD. Further studies are needed to compare the efficacy of different strategies in more homogeneous subpopulations.

Genetic variants in the promoters of let-7 family are associated with an increased risk of major depressive disorder

BACKGROUND

Let-7 family plays a critical role in the pathogenesis of major depressive disorder (MDD). Genetic polymorphisms in the promoters of miRNA may influence individual׳s susceptibility to diseases. The purpose of this study was to investigate the association between rs10877887 and rs13293512 polymorphisms in the promoters of let-7 family and the risk of MDD.

METHOD

Polymerase chain reaction-restriction fragment length polymorphism and DNA sequencing assays were used to analyze the rs10877887 and rs13293512 polymorphisms in 237 MDD patients and 296 controls.

RESULTS

We found that the rs10877887 CC genotype was associated with an increased risk of MDD (CC vs. TT: OR=1.73, 95% CI, 1.04-2.86, P=0.03, and CC vs.

TT/TC

OR=1.74, 95% CI, 1.08-2.80, P=0.02, respectively). Similarly increased risk was also observed for the rs13293512 (CC vs. TT: OR=1.83, 95% CI, 1.12-2.99, P=0.015; CC vs.

TT/TC

OR=1.84, 95% CI, 1.20-2.81, P=0.005; and C vs. T: OR=1.32, 95% CI, 1.03-1.68, P=0.03, respectively). Stratification analysis showed that patients with the rs13293512 TC and CC genotypes had a 2.29 and 2.56-fold increased risk of MDD recurrence after treatment (TC vs. TT: 95% CI, 1.23-4.25, P=0.008; CC vs. TT: 95% CI, 1.25-5.23, P=0.009, respectively).

LIMITATIONS

Relatively small sample size and hospital-based study design may influence the results.

CONCLUSIONS

Our findings suggest that the rs10877887 and rs13293512 polymorphisms may be related to the development of MDD.

Deep brain stimulation for psychiatric disorders: where we are now

Fossil records showing trephination in the Stone Age provide evidence that humans have sought to influence the mind through physical means since before the historical record. Attempts to treat psychiatric disease via neurosurgical means in the 20th century provided some intriguing initial results. However, the indiscriminate application of these treatments, lack of rigorous evaluation of the results, and the side effects of ablative, irreversible procedures resulted in a backlash against brain surgery for psychiatric disorders that continues to this day. With the advent of psychotropic medications, interest in invasive procedures for organic brain disease waned.

Diagnosis and classification of psychiatric diseases has improved, due to a better understanding of psychiatric patho-physiology and the development of disease and treatment biomarkers. Meanwhile, a significant percentage of patients remain refractory to multiple modes of treatment, and psychiatric disease remains the number one cause of disability in the world. These data, along with the safe and efficacious application of deep brain stimulation (DBS) for movement disorders, in principle a reversible process, is rekindling interest in the surgical treatment of psychiatric disorders with stimulation of deep brain sites involved in emotional and behavioral circuitry.

This review presents a brief history of psychosurgery and summarizes the development of DBS for psychiatric disease, reviewing the available evidence for the current application of DBS for disorders of the mind.

Is pindolol augmentation effective in depressed patients resistant to selective serotonin reuptake inhibitors? A systematic review and meta-analysis

OBJECTIVE

This systematic review and meta-analysis was conducted to assess the use of pindolol augmentation in depressed patients resistant to selective serotonin reuptake inhibitor (SSRI) therapy.

METHODS

A comprehensive search of PubMed, Cochrane, Embase, Web of Science, and PsychINFO databases from 1970 through December 2013 was conducted. Only randomized controlled trials (RCTs) studied on unipolar SSRI-resistant depressed adults were included. The primary outcome was mean change scores of depressive symptom on the depression rating scales, assessed with standardized mean differences.

RESULTS

Five RCTs consisting of 154 patients met all inclusion and exclusion criteria. The overall pooled effect size in the primary and secondary efficacy analysis showed no significant effects of pindolol plus SSRI therapy (standardized mean difference = -0.43, p = 0.24; OR = 1.92, p = 0.39, respectively). In terms of acceptability, there was no statistical difference in either tolerability or safety between the two groups (OR = 0.46, p = 0.40; OR = 0.90, p = 0.94, respectively). These estimates remained robust through several sensitivity and subgroup analyses, except 7.5 mg-qd pindolol augmentation did show a significant benefit over 2.5-mg tid pindolol augmentation.

CONCLUSIONS

Pindolol augmentation may not be suitable for treatment-resistant depression patients with SSRI-resistant depression. However, once-daily high-dose pindolol (7.5 mg qd) appears to show a promising benefit in these patients.

Vortioxetine: a meta-analysis of 12 short-term, randomized, placebo-controlled clinical trials for the treatment of major depressive disorder

BACKGROUND

Vortioxetine was approved by the U.S. Food and Drug Administration (FDA) in September 2013 for treating major depressive disorder (MDD). Thus far, a number of randomized, double-blind, placebo-controlled clinical trials (RCTs) of vortioxetine have been conducted in patients with MDD. We performed a meta-analysis to increase the statistical power of these studies and enhance our current understanding of the role of vortioxetine in the treatment of MDD.

METHODS

We performed an extensive search of databases and the clinical trial registry. The mean change in total scores on the 24-item Hamilton Rating Scale for Depression (HAM-D) and the Montgomery- Åsberg Depression Rating Scale (MADRS) from the baseline were the primary outcome measures. The secondary efficacy measures were the response and remission rates, as defined by a 50% or greater reduction in HAM-D/MADRS total scores and as a score of 10 or less in the MADRS and 7 or less in the HAM-D total scores at the end of treatment.

RESULTS

We included 7 published and 5 unpublished short-term (6-12 wk) RCTs in our meta-analysis. Vortioxetine was significantly more effective than placebo, with an effect size (standardized mean difference [SMD]) of -0.217 (95% confidence interval [CI] -0.313 to -0.122) and with odds ratios (ORs) for response and remission of 1.652 (95% CI 1.321 to 2.067) and 1.399 (95% CI 1.104 to 1.773), respectively. Those treated with vortioxetine did not differ significantly from those treated with selective norepinephrine reuptake inhibitors/agomelatine with regard to the SMD of the primary outcome measure (0.081, -0.062 to 0.223) or for response (OR 0.815, 95% CI 0.585 to 1.135) and remission (OR 0.843, 95% CI 0.575 to 1.238) rates. Discontinuation owing to lack of efficacy (OR 0.541, 95% CI 0.308 to 0.950) was significantly less common among those treated with vortioxetine than among those who received placebo, whereas discontinuation owing to adverse events (AEs; OR 1.530, 95% CI 1.144 to 2.047) was significantly more common among those treated with vortioxetine than among those receiving placebo. There was no significant difference in discontinuation rates between vortioxetine and comparators owing to inefficacy (OR 0.983, 95% CI 0.585 to 1.650), whereas discontinuation owing to AEs was significantly less common in the vortioxetine than in the comparator group (OR 0.728, 95% CI 0.554 to 0.957).

LIMITATIONS

Studies examining the role of vortioxetine in the treatment of MDD are limited.

CONCLUSION

Although our results suggest that vortioxetine may be an effective treatment option for MDD, they should be interpreted and translated into clinical practice with caution, as the meta-analysis was based on a limited number of heterogeneous RCTs.

Effects of buprenorphine on behavioral tests for antidepressant and anxiolytic drugs in mice

RATIONALE

Buprenorphine (BPN) has been shown to rapidly improve mood in treatment-resistant depressed patients in small clinical studies. However, BPN's effects in preclinical tests for mood and antidepressant efficacy are largely unexplored.

OBJECTIVE

The current study examined the effects of BPN in the forced swim test (FST) and novelty-induced hypophagia (NIH) test as measures of antidepressant and anxiolytic-like effects in C57BL/6 J mice. Microdialysis was used to measure whether BPN engaged kappa-opioid receptor (KORs) in the nucleus accumbens shell (NAcSh) at a behaviorally active dose (0.25 mg/kg).

METHODS

BPN was tested in the FST at both 30 min and 24 h post-administration. Also measured in the FST at 24 h post-administration were the KOR antagonist norbinaltorphimine (nor-BNI), the MOR agonist morphine and the reference antidepressant desipramine. The anxiolytic effects of BPN were examined in the NIH test 24 h after treatment. The effects of acute injection of BPN and the KOR agonist U50,488 were measured on extracellular dopamine (DA) levels in the NAcSh.

RESULTS

BPN produced significant reductions in FST immobility without changing locomotor activity and reduced approach latencies in the novel environment of the NIH test when tested 24 h after treatment. Repeated daily BPN injections for 6 days did not produce tolerance to these behavioral effects. nor-BNI produced a similar antidepressant-like response in the FST 24 h post-injection but morphine and desipramine were ineffective. BPN (0.25 mg/kg) did not alter DA levels when given alone but prevented the KOR agonist U50,488 from reducing DA levels.

CONCLUSIONS

Acute and subchronic treatment with BPN produced antidepressant and anxiolytic-like responses in mice at doses that engage KORs. These studies support the clinical evidence that BPN may be a novel rapid-acting antidepressant medication and provides rodent models for investigating associated neurochemical mechanisms.

Bilateral repetitive transcranial magnetic stimulation for treatment-resistant depression: a systematic review and meta-analysis of randomized controlled trials

There has been concern regarding the use of controversial paradigms for repetitive transcranial magnetic stimulation (rTMS) to manage treatment-resistant depression (TRD). This meta-analysis assessed the efficacy of bilateral rTMS compared with unilateral and sham rTMS in patients with TRD. PubMed, Embase, CENTRAL, PsycINFO, Web of Science, EAGLE and NTIS databases were searched to identify relevant studies, and randomized controlled trials (RCTs) on bilateral rTMS for TRD patients were included. The response was defined as the primary outcome, and remission was the secondary outcome. Ten RCTs that included 634 patients met the eligibility criteria. The risk ratio (RRs) of both the primary and secondary outcomes of bilateral rTMS showed non-significant increases compared to unilateral rTMS (RR=1.01, P=0.93; odds ratio [OR]=0.77, P=0.22). Notably, the RR of the primary bilateral rTMS outcome was significantly increased compared to that for sham rTMS (RR=3.43, P=0.0004). The results of our analysis demonstrated that bilateral rTMS was significantly more effective than sham rTMS but not unilateral rTMS in patients with TRD. Thus, bilateral rTMS may not be a useful paradigm for patients with TRD.

Repetitive transcranial magnetic stimulation in patients with drug-resistant major depression: A six-month clinical follow-up study

OBJECTIVE

In this study we aimed to assess the long-term efficacy of repetitive Transcranial Magnetic Stimulation (rTMS) on depressive symptoms and cognitive performance in patients with drug-resistant major depressive disorder (MDD).

METHODS

Fifteen drug-resistant depressed outpatients completed an acute trial with augmentative high-frequency rTMS over the left dorsolateral prefrontal cortex (DLPFC) and were compared with 15 drug-resistant MDD patients who underwent sham procedure. Depressive symptoms were evaluated with the Hamilton Depression Rating Scale and Montgomery-Asberg Depression Rating Scale. The Frontal Assessment Battery and the Stroop Color-Word Test Interference (Stroop T) were used to probe executive functions. Outcome measures were obtained at baseline, 4 weeks after the rTMS, as well as 3 months and 6 months after the end of the stimulation protocol.

RESULTS

After the active rTMS, patients showed a significant decrease in the scores at the depression rating scales that lasted for 6 months. A transient improvement was also observed at the Stroop T, although it did not persist in time.

CONCLUSIONS

High-frequency rTMS over the left DLPFC may have long-term antidepressant effect in drug-resistant MDD. TMS is a valuable tool for the add-on treatment of mood disorders and for the design of customized stimulation protocols.

Off-label use of transmucosal ketamine as a rapid-acting antidepressant: a retrospective chart review

OBJECTIVE

This study evaluated the effectiveness and safety of subanesthetic doses of ketamine using an off-label, transmucosal administration route in patients with treatment-resistant depression.

METHODS

A retrospective chart review was conducted to identify patients who met the inclusion criteria for treatment-resistant major depressive disorder. Seventeen such patients who received subanesthetic doses of ketamine were included. Patient demographics, efficacy (drug refill, clinician notes), side effects, and concurrent medications were assessed.

RESULTS

Benefit from low-dose transmucosal ketamine was noted in 76% of subjects (average age 48 years, 88% female), with a dose duration lasting 7-14 days. No notable side effects were noted. The most common classes of concurrent medications to which ketamine was added were serotonin-norepinephrine reuptake inhibitors (59%), stimulants (47%), folate replacement (47%), and benzodiazepines (47%).

CONCLUSION

Our results provide preliminary evidence of the effectiveness and safety of low-dose transmucosal ketamine in treatment-resistant patients. A controlled, prospective pilot study is warranted to validate these findings.

Exercise as an add-on strategy for the treatment of major depressive disorder: a systematic review

Antidepressants are currently the treatment of choice for major depressive disorder (MDD). Nevertheless, a high percentage of patients do not respond to a first-line antidepressant drug, and combination treatments and augmentation strategies increase the risk of side effects. Moreover, a significant proportion of patients are treatment-resistant. In the last 30 years, a number of studies have sought to establish whether exercise could be regarded as an alternative to antidepressants, but so far no specific analysis has examined the efficacy of exercise as an adjunctive treatment in combination with antidepressants. We carried out a systematic review to evaluate the effectiveness of exercise as an adjunctive treatment with antidepressants on depression. A search of relevant papers was carried out in PubMed/Medline, Google Scholar, and Scopus with the following keywords: "exercise," "physical activity," "physical fitness," "depressive disorder," "depression," "depressive symptoms," "add-on," "augmentation," "adjunction," and "combined therapy." Twenty-two full-text articles were retrieved by the search. Among the 13 papers that fulfilled our inclusion criteria, we found methodological weaknesses in the majority. However, the included studies showed a strong effectiveness of exercise combined with antidepressants. Further analyses and higher quality studies are needed; nevertheless, as we have focused on a particular intervention (exercise in adjunction to antidepressants) that better reflects clinical practice, we can hypothesize that this strategy could be appropriately and safely translated into real-world practice.

Long-term symptomatic and functional outcome following an intensive inpatient multidisciplinary intervention for treatment-resistant affective disorders

BACKGROUND

The natural history of treatment-resistant depression (TRD) is poor, with high rates of chronicity and recurrence. We describe longer-term symptomatic and functional outcome following multimodal intensive inpatient treatment for TRD.

METHODS

Symptomatic and functional outcomes were assessed in 71 participants (unipolar, n=51; bipolar, n=20) with severe TRD previously treated at a specialist inpatient unit a median of 34 months (IQR 19-52) post discharge. We looked at outcomes in defined subgroups (unipolar, bipolar and psychotic) and at symptom clusters to see whether certain aspects of depression were more resistant to treatment than others.

RESULTS

Symptomatic improvement during the admission was maintained at follow up: HDRS21 scores fell from admission (median 22; IQR 19-25) to discharge (median 12; IQR 7-16) and follow-up (median 10; IQR 4-18). Overall, two-thirds of patients were judged to have a good long-term outcome, while half remained in full remission at follow-up. Outcomes were more favourable in bipolar patients, patients without a history of psychosis and patients who were discharged in remission, although a minority of responders at discharge no longer met response criteria at follow up, and conversely some patients discharged as non-responders did subsequently respond. Non-remitting depression was characterised by three main factors; anxiety, cognitive difficulties and sleep disturbance. Those who remitted had better functional outcomes as did those who had experienced a more sustained response to treatment whilst inpatients. Quality of life was poor for those who did not respond to the treatment package.

LIMITATIONS

Variable follow-up length.

CONCLUSIONS

This difficult-to-treat population gained long-term benefits from multidisciplinary inpatient treatment. Treatment to remission was associated with more favourable outcomes. Non-responsive depression was characterised by specific symptom clusters that might be amenable to more targeted treatments.

Toolbox: Psychotropic medications for augmentation or combination in treatment-resistant depression

This toolbox compares pharmacologic options for treatment-resistant depression (TRD) that may be considered if the patient fails to experience adequate response or remission despite optimizing antidepressant therapy.

Emerging therapies for treatment resistant depression

Despite new insights and evidence-based treatment options for clinical depression in the recent years, the current choices of safe and effective therapies are still inadequate to sustain a long-term response in the depressed patient. Many do not improve, improve partially or are classified as ‘treatment resistant’ with poor compliance and marked functional impairment. The aim of this article is to review future therapeutic options and advances in treatments available for this cohort of patients. Several innovative and promising studies are underway to explore the role of ketamine, a glutamate N-methyl-d-aspartate (NMDA) antagonist in treating treatment-resistant depression and acute suicidal ideation. Furthermore, new research reveals that depression is associated with a significant drop in neurotrophic factors such as brain derived neurotrophic factor (BDNF) and increasing BDNF may be a new strategy for developing new antidepressants. Neuromodulation interventions by stimulating specific brain regions including deep brain stimulation (DBS), magnetic seizure therapy (MST), and transcranial direct current stimulation (tDCS), still in experimental stages, are also discussed.

The treatment of nonmelancholic depression: when antidepressants fail, does psychotherapy work?

OBJECTIVE

Treatment-resistant depression (TRD) is used as a descriptive or diagnostic term and has generated many management guidelines weighting antidepressant (AD) therapy, but which may be an inappropriate paradigm for the nonmelancholic disorders where psychotherapy may be a more salient modality. This study sought to evaluate the effectiveness of psychological therapy in patients whose nonmelancholic depressive condition had been resistant to at least 2 ADs.

METHOD

Principal analyses compared 32 patients, diagnosed with a nonmelancholic depression who received 12 weeks of psychological therapy, with a small control group. Comparative analyses failed to find a distinct therapeutic effect, leading to an extension study pursuing candidate explanatory factors for this lack of response, including psychosocial factors.

RESULTS

While our sample showed a 41% response and 22% remission rate to psychotherapy, their improvement pattern was similar to the control group, thus arguing against any specific therapeutic benefit. Explanatory factors nominated by the treating psychologist weighted personality issues for 35% of the patients, distal stressors for 22%, and comorbid anxiety conditions for 18%. When sample members were compared with an age- and sex-matched sample of patients with nonmelancholic depression who improved distinctly during a similar 12-week period, rates of such putative personality, stress, and anxiety risk factors did not differ, arguing against the likelihood of these factors compromising improvement.

CONCLUSIONS

Patients with nonmelancholic TRD also failed to demonstrate a clear response to a psychotherapeutic approach, while our pursuit of clinically explanatory variables was not supported empirically.

Behavioral and neurobiological effects of deep brain stimulation in a mouse model of high anxiety- and depression-like behavior

Increasing evidence suggests that high-frequency deep brain stimulation of the nucleus accumbens (NAcb-DBS) may represent a novel therapeutic strategy for individuals suffering from treatment-resistant depression, although the underlying mechanisms of action remain largely unknown. In this study, using a unique mouse model of enhanced depression- and anxiety-like behavior (HAB), we investigated behavioral and neurobiological effects of NAcb-DBS. HAB mice either underwent chronic treatment with one of three different selective serotonin reuptake inhibitors (SSRIs) or received NAcb-DBS for 1 h per day for 7 consecutive days. Animals were tested in established paradigms revealing depression- and anxiety-related behaviors. The enhanced depression-like behavior of HAB mice was not influenced by chronic SSRI treatment. In contrast, repeated, but not single, NAcb-DBS induced robust antidepressant and anxiolytic responses in HAB animals, while these behaviors remained unaffected in normal depression/anxiety animals (NAB), suggesting a preferential effect of NAcb-DBS on pathophysiologically deranged systems. NAcb-DBS caused a modulation of challenge-induced activity in various stress- and depression-related brain regions, including an increase in c-Fos expression in the dentate gyrus of the hippocampus and enhanced hippocampal neurogenesis in HABs. Taken together, these findings show that the normalization of the pathophysiologically enhanced, SSRI-insensitive depression-like behavior by repeated NAcb-DBS was associated with the reversal of reported aberrant brain activity and impaired adult neurogenesis in HAB mice, indicating that NAcb-DBS affects neuronal activity as well as plasticity in a defined, mood-associated network. Thus, HAB mice may represent a clinically relevant model for elucidating the neurobiological correlates of NAcb-DBS.

Natural polyphenols in the management of major depression

INTRODUCTION

Natural polyphenols, the non-essential micronutrients, found in array of plant products, are known to affect various physiological and biochemical functions in the body. Studies have shown the protective effect of these polyphenols in different neurological and mental disorders. These polyphenols modulate monoaminergic neurotransmission in the brain and thus possess antidepressant-like activity at least in animal models of depression.

AREAS COVERED

The present review discusses the use of these natural polyphenols in the treatment of major depression. The review article discusses the antidepressant potential of some important polyphenols such as amentoflavone, apigenin, chlorogenic acid, curcumin, ferulic acid, hesperidin, rutin, quercetin, naringenin, resveratrol, ellagic acid, nobiletin and proanthocyanidins. The mechanism of action of these polyphenols in the treatment of major depression is also discussed in detail.

EXPERT OPINION

There is an exciting prospect in the discovery of natural polyphenols as therapeutic agents in the treatment of major depression.

Therapeutic doses of antidepressants are projected not to inhibit human α4β2 nicotinic acetylcholine receptors

Inhibition of central α4β2 nAChRs by antidepressants, proposed to contribute to their clinical efficacy, was assessed for monoamine reuptake inhibitors (amitriptyline, nortriptyline, fluoxetine, sertraline, paroxetine, citalopram) by comparing projected human unbound brain drug concentrations (Cu,b) at therapeutic doses with concentrations that inhibit human α4β2 nAChRs in vitro. Inhibitory concentrations (IC50) were determined by patch clamp and ranged from 0.8-3.2 μM, except for nortriptyline (IC50 = 100 nM). Cu,b values were calculated from human unbound plasma drug concentrations (Cu,p) and rat-derived brain-to-plasma and extracellular fluid-to-plasma ratios for the unbound drug, which are near unity, due to much higher brain tissue binding than plasma protein binding of these drugs. Accordingly in humans, antidepressant Cu,b are projected to essentially equal Cu,p, with average values from 3-87 nM, which are 30-to-250-fold below their IC50 concentrations. Based on our model, monoaminergic antidepressants minimally inhibit central nAChRs and it is unlikely that α4β2 nAChR antagonism contributes to their antidepressant activity. Nortriptyline is an exception with a Cu,b that is 2-fold below its IC50, which is comparable to the nAChR antagonist (±)-mecamylamine, for which Cu,b is 4-fold below its IC50; both drugs will inhibit a substantial fraction of α4β2 nAChRs. The Cu,b of the α4β2 nAChR partial agonist varenicline, which has antidepressant-like activity in a murine model, is higher than its IC50 and varenicline is projected to cause ~70% inhibition of α4β2 nAChRs. Taken together these data may help explain the negative outcome of recent antidepressant augmentation trials with mecamylamine and the partial agonist CP-601927.

Mood disorders and complementary and alternative medicine: a literature review

Mood disorders are a major public health problem and are associated with considerable burden of disease, suicides, physical comorbidities, high economic costs, and poor quality of life. Approximately 30%-40% of patients with major depression have only a partial response to available pharmacological and psychotherapeutic interventions. Complementary and alternative medicine (CAM) has been used either alone or in combination with conventional therapies in patients with mood disorders. This review of the literature examines evidence-based data on the use of CAM in mood disorders. A search of the PubMed, Medline, Google Scholar, and Quertile databases using keywords was conducted, and relevant articles published in the English language in the peer-reviewed journals over the past two decades were retrieved. Evidence-based data suggest that light therapy, St John's wort, Rhodiola rosea, omega-3 fatty acids, yoga, acupuncture, mindfulness therapies, exercise, sleep deprivation, and S-adenosylmethionine are effective in the treatment of mood disorders. Clinical trials of vitamin B complex, vitamin D, and methylfolate found that, while these were useful in physical illness, results were equivocal in patients with mood disorders. Studies support the adjunctive role of omega-3 fatty acids, eicosapentaenoic acid, and docosahexaenoic acid in unipolar and bipolar depression, although manic symptoms are not affected and higher doses are required in patients with resistant bipolar depression and rapid cycling. Omega-3 fatty acids are useful in pregnant women with major depression, and have no adverse effects on the fetus. Choline, inositol, 5-hydroxy-L-tryptophan, and N-acetylcysteine are effective adjuncts in bipolar patients. Dehydroepiandrosterone is effective both in bipolar depression and depression in the setting of comorbid physical disease, although doses should be titrated to avoid adverse effects. Ayurvedic and homeopathic therapies have the potential to improve symptoms of depression, although larger controlled trials are needed. Mind-body-spirit and integrative medicine approaches can be used effectively in mild to moderate depression and in treatment-resistant depression. Currently, although CAM therapies are not the primary treatment of mood disorders, level 1 evidence could emerge in the future showing that such treatments are effective.