Treatment-resistant depression: a challenge for future research

Electrophysiological correlates and predictors of the antidepressant response to repeated ketamine infusions in treatment-resistant depression

BACKGROUND

Sub-anesthetic ketamine doses rapidly reduce depressive symptoms, although additional investigations of the underlying neural mechanisms and the prediction of response outcomes are needed. Electroencephalographic (EEG)-derived measures have shown promise in predicting antidepressant response to a variety of treatments, and are sensitive to ketamine administration. This study examined their utility in characterizing changes in depressive symptoms following single and repeated ketamine infusions.

METHODS

Recordings were obtained from patients with treatment-resistant major depressive disorder (MDD) (N = 24) enrolled in a multi-phase clinical ketamine trial. During the randomized, double-blind, crossover phase (Phase 1), patients received intravenous ketamine (0.5 mg/kg) and midazolam (30 μg/kg), at least 1 week apart. For each medication, three resting, eyes-closed recordings were obtained per session (pre-infusion, immediately post-infusion, 2 h post-infusion), and changes in power (delta, theta1/2/total, alpha1/2/total, beta, gamma), alpha asymmetry, theta cordance, and theta source-localized anterior cingulate cortex activity were quantified. The relationships between ketamine-induced changes with early (Phase 1) and sustained (Phases 2,3: open-label repeated infusions) decreases in depressive symptoms (Montgomery-Åsberg Depression Rating Score, MADRS) and suicidal ideation (MADRS item 10) were examined.

RESULTS

Both medications decreased alpha and theta immediately post-infusion, however, only midazolam increased delta (post-infusion), and only ketamine increased gamma (immediately post- and 2 h post-infusion). Regional- and frequency-specific ketamine-induced EEG changes were related to and predictive of decreases in depressive symptoms (theta, gamma) and suicidal ideation (alpha). Early and sustained treatment responders differed at baseline in surface-level and source-localized theta.

CONCLUSIONS

Ketamine exerts frequency-specific changes on EEG-derived measures, which are related to depressive symptom decreases in treatment-resistant MDD and provide information regarding early and sustained individual response to ketamine.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov: Action of Ketamine in Treatment-Resistant Depression, NCT01945047.

Therapeutic approaches employing natural compounds and derivatives for treating bipolar disorder: emphasis on experimental models of the manic phase

Bipolar disorder (BD) is a complex psychiatric disease characterized by mood swings that include episodes of mania and depression. Given its cyclical nature, BD is especially hard to model; however, the standard practice has been to mimic manic episodes in animal models. Despite scientific advances, the pathophysiology of BD is not fully understood, and treatment remains limited. In the last years, natural products have emerged as potential neuroprotective agents for the treatment of psychiatric diseases. Thus, the aim of this review was to explore the therapeutic potential of natural compounds and derivatives against BD, taking into account preclinical and clinical studies. Reliable articles indexed in databases such as PubMed, Web of Science and Science Direct were used. In clinical studies, treatment with herbal plants extracts, omega-3, inositol, n-acetylcysteine and vitamin D has been associated with a clinical improvement in symptoms of mania and depression in BD patients. In animal models, it has been shown that red fruits extracts, curcumin, quercetin, gallic acid, alpha-lipoic acid and carvone can modulate many neurochemical pathways involved in the pathophysiology of manic episodes. Thus, this review appointed the advances in the consumption of natural compounds and derivatives as an important therapeutic strategy to mitigate the symptoms of BD.

Results of the European Group for the Study of Resistant Depression (GSRD) - basis for further research and clinical practice

Objectives: The overview outlines two decades of research from the European Group for the Study of Resistant Depression (GSRD) that fundamentally impacted evidence-based algorithms for diagnostics and psychopharmacotherapy of treatment-resistant depression (TRD). Methods: The GSRD staging model characterising response, non-response and resistance to antidepressant (AD) treatment was applied to 2762 patients in eight European countries. Results: In case of non-response, dose escalation and switching between different AD classes did not show superiority over continuation of original AD treatment. Predictors for TRD were symptom severity, duration of the current major depressive episode (MDE), suicidality, psychotic and melancholic features, comorbid anxiety and personality disorders, add-on treatment, non-response to the first AD, adverse effects, high occupational level, recurrent disease course, previous hospitalisations, positive family history of MDD, early age of onset and novel associations of single nucleoid polymorphisms (SNPs) within the PPP3CC, ST8SIA2, CHL1, GAP43 and ITGB3 genes and gene pathways associated with neuroplasticity, intracellular signalling and chromatin silencing. A prediction model reaching accuracy of above 0.7 highlighted symptom severity, suicidality, comorbid anxiety and lifetime MDEs as the most informative predictors for TRD. Applying machine-learning algorithms, a signature of three SNPs of the BDNF, PPP3CC and HTR2A genes and lacking melancholia predicted treatment response. Conclusions: The GSRD findings offer a unique and balanced perspective on TRD representing foundation for further research elaborating on specific clinical and genetic hypotheses and treatment strategies within appropriate study-designs, especially interaction-based models and randomized controlled trials.

Treatment of Depression From a Self-Regulation Perspective: Basic Concepts and Applied Strategies in Self-System Therapy

Self-regulation models of psychopathology provide a theory-based, empirically supported framework for developing psychotherapeutic interventions that complement and extend current cognitive-behavioral models. However, many clinicians are only minimally familiar with the psychology of self-regulation. The aim of the present manuscript is twofold. First, we provide an overview of self-regulation as a motivational process essential to well-being and introduce two related theories of self-regulation which have been applied to depression. Second, we describe how self-regulatory concepts and processes from those two theories have been translated into psychosocial interventions, focusing specifically on self-system therapy (SST), a brief structured treatment for depression that targets personal goal pursuit. Two randomized controlled trials have shown that SST is superior to cognitive therapy for depressed clients with specific self-regulatory deficits, and both studies found evidence that SST works in part by restoring adaptive self-regulation. Self-regulation-based psychotherapeutic approaches to depression hold significant promise for enhancing treatment efficacy and ultimately may provide an individualizable framework for treatment planning.

Prevalence of ADHD symptoms across clinical stages of major depressive disorder

BACKGROUND

Depression and ADHD often co-occur in clinical samples. Depression severity may be linked to ADHD symptomatology. We therefore assessed ADHD symptoms across clinical stages of major depressive disorder (MDD).

METHODS

We used 4-year follow-up data of the Netherlands Study of Depression and Anxiety (September 2008 until April 2011), including healthy controls, groups with remitted and current MDD (N=2053; age range 21-69 years; 66.8% females). Probable ADHD was defined as having current ADHD symptoms on the Conners Adult ADHD Rating Scale and a positive score on childhood or early-adolescent ADHD indicators. We examined ADHD symptom rates across (i) those with and without lifetime MDD, (ii) clinical characteristics of MDD including severity, course and outcomes, (iii) clinical stages of MDD.

RESULTS

(i) The prevalence of ADHD symptoms was 0.4% in healthy controls, 5.7% in remitted MDD and 22.1% in current MDD (OR=4.5; 95% CI 3.1-6.5). (ii) ADHD symptom rates and odds were significantly increased among those with more severe depression (29.4%; OR=6.8; 95% CI 2.9-16.1), chronic depression (21.8%; OR=3.8; 95% CI 2.5-5.7), earlier age of onset of depressive symptoms (9.9%; OR=1.5; 95% CI 1.0-2.3), and comorbid anxiety disorders (29.0%; OR=3.4; 95% CI 2.0-5.7). (iii) ADHD symptom rates increased across clinical stages of MDD, up to 22.5% in chronic MDD.

LIMITATIONS

We used self-reports on ADHD symptoms. Also, clinical staging models have not yet been validated for mental disorders.

CONCLUSIONS

ADHD symptoms are very common among MDD patients, especially among those in recurrent and chronic stages of MDD. Considering ADHD may be an important step forward in improving the treatment of depression.

Reversal of corticosterone-induced BDNF alterations by the natural antioxidant alpha-lipoic acid alone and combined with desvenlafaxine: Emphasis on the neurotrophic hypothesis of depression

Brain derived neurotrophic factor (BDNF) is linked to the pathophysiology of depression. We hypothesized that BDNF is one of the neurobiological pathways related to the augmentation effect of alpha-lipoic acid (ALA) when associated with antidepressants. Female mice were administered vehicle or CORT 20mg/kg during 14 days. From the 15th to 21st days the animals were divided in groups that were further administered: vehicle, desvenlafaxine (DVS) 10 or 20mg/kg, ALA 100 or 200mg/kg or the combinations of DVS10+ALA100, DVS20+ALA100, DVS10+ALA200 or DVS20+ALA200. ALA or DVS alone or in combination reversed CORT-induced increase in immobility time in the forced swimming test and decrease in sucrose preference, presenting, thus, an antidepressant-like effect. DVS10 alone reversed CORT-induced decrease in BDNF in the prefrontal cortex (PFC), hippocampus (HC) and striatum (ST). The same was observed in the HC and ST of ALA200 treated animals. The combination of DVS and ALA200 reversed CORT-induced alterations in BDNF and even, in some cases, increased the levels of this neurotrophin when compared to vehicle-treated animals in HC and ST. Taken together, these results suggest that the combination of the DVS+ALA may be valuable for treating conditions in which BDNF levels are decreased, such as depression.