Remission in major depression with two antidepressant mechanisms: results from a naturalistic study

Sex differences in the transcription of glutamate transporters in major depression and suicide

BACKGROUND

Accumulating evidence indicates that the glutamate system contributes to the pathophysiology of major depressive disorder (MDD) and suicide. We previously reported higher mRNA expression of glutamate receptors in the dorsolateral prefrontal cortex (DLPFC) of females with MDD.

METHODS

In the current study, we measured the expression of mRNAs encoding glutamate transporters in the DLPFC of MDD subjects who died by suicide (MDD-S, n = 51), MDD non-suicide subjects (MDD-NS, n = 28), and individuals who did not have a history of neurological illness (CTRL, n = 32).

RESULTS

Females but not males with MDD showed higher expression of EAATs and VGLUTs relative to CTRLs. VGLUT expression was significantly higher in the female MDD-S group, relative to the other groups. EAAT expression was lower in the male violent suicides.

LIMITATIONS

This study has limitations common to most human studies, including medication history and demographic differences between the diagnostic groups. We mitigated the effects of confounders by including them as covariates in our analyses.

CONCLUSIONS

We report sex differences in the expression of glutamate transporter genes in the DLPFC in MDD. Increased neuronal glutamate transporter expression may increase synaptic glutamate, leading to neuronal and glial loss in the DLPFC in MDD. These deficits may lower DLPFC activity, impair problem solving and impair executive function in depression, perhaps increasing vulnerability to suicidal behavior. These data add to accumulating support for the hypothesis that glutamatergic transmission is dysregulated in MDD and suicide. Glutamate transporters may be novel targets for the development of rapidly acting antidepressant therapies.

The Emerging Role of SGK1 (Serum- and Glucocorticoid-Regulated Kinase 1) in Major Depressive Disorder: Hypothesis and Mechanisms

Major depressive disorder (MDD) is a heterogeneous psychiatric disease characterized by persistent low mood, diminished interests, and impaired cognitive and social functions. The multifactorial etiology of MDD is still largely unknown because of the complex genetic and environmental interactions involved. Therefore, no established mechanism can explain all the aspects of the disease. In this light, an extensive research about the pathophysiology of MDD has been carried out. Several pathogenic hypotheses, such as monoamines deficiency and neurobiological alterations in the stress-responsive system, including the hypothalamic-pituitary-adrenal (HPA) axis and the immune system, have been proposed for MDD. Over time, remarkable studies, mainly on preclinical rodent models, linked the serum- and glucocorticoid-regulated kinase 1 (SGK1) to the main features of MDD. SGK1 is a serine/threonine kinase belonging to the AGK Kinase family. SGK1 is ubiquitously expressed, which plays a pivotal role in the hormonal regulation of several ion channels, carriers, pumps, and transcription factors or regulators. SGK1 expression is modulated by cell stress and hormones, including gluco- and mineralocorticoids. Compelling evidence suggests that increased SGK1 expression or function is related to the pathogenic stress hypothesis of major depression. Therefore, the first part of the present review highlights the putative role of SGK1 as a critical mediator in the dysregulation of the HPA axis, observed under chronic stress conditions, and its controversial role in the neuroinflammation as well. The second part depicts the negative regulation exerted by SGK1 in the expression of both the brain-derived neurotrophic factor (BDNF) and the vascular endothelial growth factor (VEGF), resulting in an anti-neurogenic activity. Finally, the review focuses on the antidepressant-like effects of anti-oxidative nutraceuticals in several preclinical model of depression, resulting from the restoration of the physiological expression and/or activity of SGK1, which leads to an increase in neurogenesis. In summary, the purpose of this review is a systematic analysis of literature depicting SGK1 as molecular junction of the complex mechanisms underlying the MDD in an effort to suggest the kinase as a potential biomarker and strategic target in modern molecular antidepressant therapy.

New hypothesis and treatment targets of depression: an integrated view of key findings

Major depressive disorder (MDD) is a common and devastating psychiatric disorder characterized by persistent low mood, cognitive disorder, and impaired social function. Despite its complex mechanisms, increasing evidence has identified the involvement of neurotrophic factors, inflammatory cytokines, the hypothalamus-pituitary-adrenal axis, and glutamate receptors in the pathophysiology of this illness. The present review synthesizes recent research achievements to define the network between different hypotheses of MDD and to understand which part is most pivotal for its pathogenesis. By integrating MDD-related signal pathways, we highlight brain-derived neurotrophic factor (BDNF) dysfunction and increased apoptosis as the final common cascades, and new therapeutic strategies aiming to enhance BDNF function have been shown to exert a rapid and effective antidepressant action.

Milnacipran: a unique antidepressant?

Tricyclic antidepressants (TCAs) are among the most effective antidepressants available, although their poor tolerance at usual recommended doses and toxicity in overdose make them difficult to use. While selective serotonin reuptake inhibitors (SSRIs) are better tolerated than TCAs, they have their own specific problems, such as the aggravation of sexual dysfunction, interaction with coadministered drugs, and for many, a discontinuation syndrome. In addition, some of them appear to be less effective than TCAs in more severely depressed patients. Increasing evidence of the importance of norepinephrine in the etiology of depression has led to the development of a new generation of antidepressants, the serotonin and norepinephrine reuptake inhibitors (SNRIs). Milnacipran, one of the pioneer SNRIs, was designed from theoretic considerations to be more effective than SSRIs and better tolerated than TCAs, and with a simple pharmacokinetic profile. Milnacipran has the most balanced potency ratio for reuptake inhibition of the two neurotransmitters compared with other SNRIs (1:1.6 for milnacipran, 1:10 for duloxetine, and 1:30 for venlafaxine), and in some studies milnacipran has been shown to inhibit norepinephrine uptake with greater potency than serotonin (2.2:1). Clinical studies have shown that milnacipran has efficacy comparable with the TCAs and is superior to SSRIs in severe depression. In addition, milnacipran is well tolerated, with a low potential for pharmacokinetic drug-drug interactions. Milnacipran is a first-line therapy suitable for most depressed patients. It is frequently successful when other treatments fail for reasons of efficacy or tolerability.

Augmentation with olanzapine in TCA-refractory depression with melancholic features: a consecutive case series

Using an 8-week, open label study design, we report the effect of augmentation strategy with olanzapine in hospitalized depressive patients with melancholic features who had insufficient response to a tricyclic antidepressant (TCA), amitriptyline. Subjects were hospitalized patients meeting the criteria of DSM-IV major depressive disorder with melancholic features who had been suffering from residual symptoms after treatment of amitriptyline. After study entry, olanzapine was added to amitriptyline and the dose was adjusted according to patients' clinical condition. Data were analyzed using an intent-to-treat methodology, with last observation carried forward. Paired t-test was adopted to assess the data from baseline to endpoint. Of 26 patients who enrolled in this study, 23 patients completed the trial and 3 patients dropped out. The mean dose of olanzapine was 6.5 (SD = 2.4) mg/day. The mean score of Montgomery-Asberg Depression Rating Scale (MADRS) was significantly decreased from 33.6 (SD = 3.5) to 20.8 (SD = 9.1) during this study (37.9% from baseline) (p < 0.001). Ten patients (38.5%) were considered as responders (50% or greater reduction in MADRS scores from baseline). These results suggest that augmentation with olanzapine in TCAs-resistant melancholia may be effective and well tolerated. We cannot draw any conclusion with certainty from the open-label, uncontrolled clinical trial. Double blind, controlled trial is needed to confirm this preliminary finding.

Negative symptoms: A review of schizophrenia, melancholic depression and Parkinson's disease

Negative symptoms generally refer to a reduction in normal functioning. In schizophrenia they encompass apathy, anhedonia, flat affect, avolition, social withdrawal and, on some accounts, psychomotor retardation. Negative symptoms have been identified in other psychiatric disorders, including melancholic depression, and also in neurological disorders, such Parkinson's disease. Achieving a better understanding of negative symptoms constitutes a priority in mental health. Primarily, negative symptoms represent an unrelenting, intractable and disabling feature for patients, often amounting to a severe burden on families, carers and the patients themselves. Identifying and understanding subgroups within disorders may also contribute to the clinical care and scientific understanding of the pathophysiology of these disorders. The purpose of this paper is to review the current literature on negative symptoms in schizophrenia and explore the idea that negative symptoms may play an important role not only in other psychiatric disorders such as melancholic depression, but also in neurological disorders, such as Parkinson's disease. In each disorder negative symptoms manifest with similar motor and cognitive impairments and are associated with comparable neuropathological and biochemical findings, possibly reflecting analogous impairments in the functioning of frontostriatal-limbic circuits.

Serotonin noradrenaline reuptake inhibitors: Logical evolution of antidepressant development

Although considerable progress has been made in improving the tolerability of antidepressant drugs, the classical tricyclic antidepressants (TCA) are still a standard for efficacy. The selective serotonin reuptake inhibitors (SSRI) are much better tolerated than the TCAs, but their antidepressant efficacy is, at best, equivalent and probably inferior to the TCA, clomipramine, in many situations. The introduction of the SSRIs naturally focussed both fundamental and clinical research effort on the role of serotonin (5-HT) in the pharmacogenesis and pharmacotherapy of depression. More recently the probable role of noradrenaline (NA) has been "rediscovered" and increasingly both 5-HT and NA dysfunctions are seen as fundamental to depressive illness. The therapeutic importance of this has been underlined by studies showing the increased antidepressant efficacy obtained when selective serotonergic drugs have been used in conjunction with selective noradrenergic drugs. The development of the new class of serotonin and noradrenaline reuptake inhibitors (SNRI) was a logical extension of these ideas. Compounds of this class, which currently comprises venlafaxine, milnacipran and duloxetine, act to inhibit the reuptake of both monoamines with no direct actions at postsynaptic receptors. Although, by definition all three SNRIs have actions on both 5-HT and NA neurotransmission, they do not all have equal potency for both transmitters. Venlafaxine has a 30-fold higher affinity for 5-HT than NA while duloxetine has a 10-fold selectivity for 5-HT. Only milnacipran is balanced between the two neurotransmitters with an approximately equal potency for the inhibition of reuptake of 5-HT and NA both in vitro and in vivo. At high doses venlafaxine and duloxetine appear to be superior to SSRIs but not at lower doses. Duloxetine is, however, not licensed in the EU at these higher doses. Milnacipran at usual doses appears more effective than SSRIs with efficacy which is similar to TCAs but with a lower side effect burden.

Combined treatment with sulpiride and paroxetine for accelerated response in patients with major depressive disorder

Although serotonin reuptake inhibitors are recommended as first-line agents for major depressive disorder, delayed onset of action is problematic, and faster effective treatment is needed. Sulpiride, a dopamine-mediated agent, has been reported to show faster antidepressant efficacy, and we examined the efficacy of adjunctive sulpiride in combination with paroxetine (PAX), compared with PAX alone, to clarify whether the combined treatment exerts faster effect. Forty-one major depressive disorder patients were enrolled in this 12-week open-label trial and were randomly assigned to a PAX (10-40 mg/d) or a PAX (10-40 mg/d) plus sulpiride (100 mg/d) group. Assessments included the Montgomery-Asberg Depression Rating Scale, the 17-item Hamilton Rating Scale for Depression, and the Zung Self-rating Depression Scale on an intent-to-treat basis, and safety was also monitored. Thirty-three patients completed the study. Both PAX + sulpiride and PAX treatments showed a mean reduction in the total Montgomery-Asberg Depression Rating Scale score of 34.4 to 5.6 and 32.2 to 10.4, respectively (P < 0.001). The combined treatment group had a significantly superior outcome in terms of the change in the total Montgomery-Asberg Depression Rating Scale, Hamilton Rating Scale for Depression, and Zung Self-rating Depression Scale scores between week 1 and the study end point (P < 0.05). Median times to response among responders alone for the combined treatment and monotherapy were 2 and 6 weeks, respectively. Both treatments were well tolerated, with no clinically significant differences in safety measures except for an elevation of prolactin in the combined treatment group. The combination treatment may be a safe and effective strategy for accelerating antidepressant response.

SNRIs: their pharmacology, clinical efficacy, and tolerability in comparison with other classes of antidepressants

The class of serotonin and norepinephrine reuptake inhibitors (SNRIs) now comprises three medications: venlafaxine, milnacipran, and duloxetine. These drugs block the reuptake of both serotonin (5-HT) and norepinephrine with differing selectivity. Whereas milnacipran blocks 5-HT and norepinephrine reuptake with equal affinity, duloxetine has a 10-fold selectivity for 5-HT and venlafaxine a 30-fold selectivity for 5-HT. All three SNRIs are efficacious in treating a variety of anxiety disorders. There is no evidence for major differences between SNRIs and SSRIs in their efficacy in treating anxiety disorders. In contrast to SSRIs, which are generally ineffective in treating chronic pain, all three SNRIs seem to be helpful in relieving chronic pain associated with and independent of depression. Tolerability of an SNRI at therapeutic doses varies within the class. Although no direct comparative data are available, venlafaxine seems to be the least well-tolerated, combining serotonergic adverse effects (nausea, sexual dysfunction, withdrawal problems) with a dose-dependent cardiovascular phenomenon, principally hypertension. Duloxetine and milnacipran appear better tolerated and essentially devoid of cardiovascular toxicity.

[Pharmacological treatment of depression]

Depression is a disorder with higher prevalence that generates important costs in the personal and socioeconomic fields. We have currently various antidepressants drugs for its treatment. In this article a review of these drugs is carried out, including various approaches necessary for addressing the special characteristics of each clinical situation. Pharmacological strategies for resistant depression are evaluated later. Finally, the future research lines are analyzed in order to improve the pharmacological depression treatment.

Empirical testing of two models for staging antidepressant treatment resistance

BACKGROUND

An increasing amount of attention has been paid to treatment resistant depression. Although it is quite common to observe nonremission to not just one but consecutive antidepressant treatments during a major depressive episode, a relationship between the likelihood of achieving remission and one's degree of resistance is not clearly known at this time. This study was undertaken to empirically test 2 recent models for staging treatment resistance.

MATERIALS AND METHODS

Psychiatrists from 2 academic sites reviewed charts of patients on their caseloads. Clinical Global Impressions-Severity (CGI-S) and Clinical Global Impressions-Improvement (CGI-I) scales were used to measure severity of depression and response to treatment, and 2 treatment-resistant staging scores were classified for each patient using the Massachusetts General Hospital staging method (MGH-S) and the Thase and Rush staging method (TR-S).

RESULTS

Out of the 115 patient records reviewed, 58 (49.6%) patients remitted at some point during treatment. There was a significant positive correlation between the 2 staging scores, and logistic regression results indicated that greater MGH-S scores, but not TR-S scores, predicted nonremission.

CONCLUSIONS

This study suggests that the hierarchical manner in which the field has typically gauged levels of treatment resistance may not be strongly supported by empirical evidence. This study suggests that the MGH staging model may offer some advantages over the staging method by Thase and Rush, as it generates a continuous score that considers both number of trials and intensity/optimization of each trial.