Response inhibition related neural oscillatory patterns show reliable early identification of bipolar from unipolar depression in a Go/No-Go task

BACKGROUND

Response inhibition is a key neurocognitive factor contributing to impulsivity in mood disorders. Here, we explored the common and differential alterations of neural circuits associated with response inhibition in bipolar disorder (BD) and unipolar disorder (UD) and whether the oscillatory signatures can be used as early biomarkers in BD.

METHODS

39 patients with BD, 36 patients with UD, 29 patients initially diagnosed with UD who later underwent diagnostic conversion to BD, and 36 healthy controls performed a Go/No-Go task during MEG scanning. We carried out time-frequency and connectivity analysis on MEG data. Further, we performed machine learning using oscillatory features as input to identify bipolar from unipolar depression at the early clinical stage.

RESULTS

Compared to healthy controls, patients had reduced rIFG-to-pre-SMA connectivity and delayed activity of rIFG. Among patients, lower beta power and higher peak frequency were observed in BD patients than in UD patients. These changes enabled accurate classification between BD and UD with an accuracy of approximately 80 %.

CONCLUSIONS

The inefficiency of the prefrontal control network is a shared mechanism in mood disorders, while the abnormal activity of rIFG is more specific to BD. Neuronal responses during response inhibition could serve as a diagnostic biomarker for BD in early stage.

Using digital phenotyping to classify bipolar disorder and unipolar disorder - exploratory findings using machine learning models

The aims were to investigate 1) differences in smartphone-based data on phone usage between bipolar disorder (BD) and unipolar disorder (UD) and 2) by using machine learning models, the sensitivity, specificity, and AUC of the combined smartphone data in classifying BD and UD. Daily smartphone-based self-assessments of mood and same-time passively collected smartphone data on smartphone usage was available for six months. A total of 64 patients with BD and 74 patients with UD were included. Patients with BD during euthymic states compared with UD in euthymic states had a lower number of incoming phone calls/ day (B: -0.70, 95%CI: -1.37; -0.70, p=0.040). Patients with BD during depressive states had a lower number of incoming and outgoing phone calls/ day as compared with patients with UD in depressive states. In classification by using machine learning models, 1) overall (regardless of the affective state), patients with BD were classified with an AUC of 0.84, which reduced to 0.48 when using a leave-one-patient-out crossvalidation (LOOCV) approach; similarly 2) during a depressive state, patients with BD were classified with an AUC of 0.86, which reduced to 0.42 with LOOCV; 3) during a euthymic state, patients with BD were classified with an AUC of 0.87, which reduced to 0.46 with LOOCV. While digital phenotyping shows promise in differentiating between patients with BD and UD, it highlights the challenge of generalizing to unseen individuals. It should serve as an complement to comprehensive clinical evaluation by clinicians.

Shared and specific neurobiology in bipolar disorder and unipolar disorder: Evidence based on the connectome gradient and a transcriptome-connectome association study

BACKGROUND

Distinguishing bipolar disorder (BD) and unipolar disorder (UD) remains challenging. To identify the common and diagnosis-specific neuropathological alterations and their potential molecular mechanisms in patients with UD and BD (with a current depressive episode).

METHODS

Resting-state functional magnetic resonance imaging was obtained from 279 participants (95 BD patients, 107 UD patients and 77 health controls). Connectome gradients analysis was performed to explore the shared and diagnosis-specific gradient alterations in BD and UD. The Allen Human Brain Atlas data was used to explore the potential gene mechanisms of the gradient alterations.

RESULTS

BD and UD had shared hierarchical disorganisation, including downgrading and contraction from the unimodal sensory networks (vision and sensorimotor) to the transmodal cognitive networks (limbic, frontoparietal, dorsal attention, and default) (all P < 0.05, FDR corrected) in gradient 1 and gradient 2. The BD patients had specific connectome gradient dysfunction in the subcortical network. Moreover, the hierarchical disorganisation was closely correlated with profiles of gene expression specific to the neuroglial cells in the prefrontal cortex in BD and UD, while the most correlated gene ontology biological processes and function were concentrated in synaptic signalling, calcium ion binding, and transmembrane transporter activity.

CONCLUSION

These findings reveal the shared and diagnosis-specific neurobiological mechanism underlying BD and UD patients, which advances our understanding of the neuromechanisms of these disorders.

Gamma band VMPFC-PreCG.L connection variation after the onset of negative emotional stimuli can predict mania in depressive patients

OBJECTIVE

Because of the similar clinical symptoms, it is difficult to distinguish unipolar disorder (UD) from bipolar disorder (BD) in the depressive episode using the available clinical features, especially for those who meet the diagnostic criteria of UD, however, experience the manic episode during the follow-up (tBD).

METHODS

Magnetoencephalography recordings during a sad expression recognition task were obtained from 81 patients (27 BD, 24 tBD, 30 UD) and 26 healthy controls (HCs). Source analysis was applied to localize 64 regions of interest in the low gamma band (30-50 Hz). Regional functional connections (FCs) were constructed respectively within three time periods (early: 0-200 ms, middle: 200-400 ms, and post: 400-600 ms). The network-based statistic method was used to explore the abnormal connection patterns in tBD compared to UD and HC. BD was applied to explore whether such abnormality is still significant between every two groups of BD, tBD, UD, and HC.

RESULTS

The VMPFC-PreCG.L connection was found to be a significantly different connection between tBD and UD in the early time period and between tBD and BD in the middle time period. Furthermore, the middle/early time period ratio of FC value of VMPFC-PreCG.L connection was negatively correlated with the bipolarity index in tBD.

CONCLUSIONS

The VMPFC-PreCG.L connection in different time periods after the onset of sad facial stimuli may be a potential biomarker to distinguish the different states of BD. The FC ratio of VMPFC-PreCG.L connection may predict whether patients with depressive episodes subsequently develop mania.

Differences in mobility patterns according to machine learning models in patients with bipolar disorder and patients with unipolar disorder

BACKGROUND

It is essential to differentiate bipolar disorder (BD) from unipolar disorder (UD) as the course of illness and treatment guidelines differ between the two disorders. Measurements of activity and mobility could assist in this discrimination.

AIMS

1) To investigate differences in smartphone-based location data between BD and UD, and 2) to investigate the sensitivity, specificity, and AUC of combined location data in classifying BD and UD.

METHODS

Patients with BD and UD completed smartphone-based self-assessments of mood for six months, along with same-time passively collected smartphone data on location reflecting mobility patterns, routine and location entropy (chaos). A total of 65 patients with BD and 75 patients with UD were included.

RESULTS

A total of 2594 (patients with BD) and 2088 (patients with UD) observations of smartphone-based location data were available. During a depressive state, compared with patients with UD, patients with BD had statistically significantly lower mobility (e.g., total duration of moves per day (e^B 0.74, 95% CI 0.57; 0.97, p = 0.027)). In classification models during a depressive state, patients with BD versus patients with UD, there was a sensitivity of 0.70 (SD 0.07), a specificity of 0.77 (SD 0.07), and an AUC of 0.79 (SD 0.03).

LIMITATIONS

The relative low symptom severity in the present study may have contributed to the magnitude of the AUC.

CONCLUSION

Mobility patterns derived from mobile location data is a promising digital diagnostic marker in discriminating between patients with BD and UD.

Efficacy, safety and tolerability of formula-based unilateral vs bilateral electroconvulsive therapy in the treatment of major depression: A randomized open label controlled trial

Electroconvulsive therapy (ECT) remains the most effective treatment of depression, though it is still unclear which of its type is the most beneficial. The aim of this study was to compare the formula-based right unilateral ECT (RUL) with the fronto-temporal bilateral ECT (BT), in terms of their efficacy, safety and tolerability in patients with bipolar or unipolar depression. Ninety-one patients were randomly assigned to either BT (n = 45) or RUL (n = 46) ECT. Brief pulse width (0.5 ms) and a formula-based dosing method were applied. The clinical efficacy was assessed using the Hamilton Depression Rating Scale (HDRS-21).The somatic state was monitored throughout the ECT course and cognitive examination included: general cognitive performance, executive functions, visual-spatial functions, verbal fluency, verbal memory and autobiographical memory. Efficacy outcomes were not found to be significantly different between groups when using higher doses of energy in RUL ECT. Patients in RUL group were less likely to be confused and experienced increased blood pressure. The indices of general cognitive performance and verbal auditory memory were also significantly better this group, while BT ECT did not change these functions. Both ECT types resulted in a decline in the retrieval consistency of autobiographical memory that persists for at least three months and was significantly more marked in BT group as compared to RUL. In conclusion, formula-based RUL ECT does not differ from BT in antidepressant efficacy and has an advantage in terms of safety (lower incidence of increased blood pressure and fewer disturbances of consciousness) and tolerability (impact on cognitive functions).

Clinical characteristics associated with the discrepancy between subjective and objective cognitive impairment in depression

BACKGROUND

Patients with unipolar disorder (UD) commonly experience cognitive dysfunction during symptomatic and remitted phases. However, it is not necessarily the patients with the greatest subjective complaints, who display the largest objectively-measured deficits on neuropsychological tests.

OBJECTIVE

This report investigated the demographic and clinical factors associated with the discrepancy between subjective and objective measures of cognition in two separate depressed patient populations in Denmark and New Zealand, respectively, using a new methodology.

METHODS

Data from 137 depressed patients and 103 healthy controls including neuropsychological test scores, self-reported cognitive difficulties, and ratings of mood were pooled from two studies conducted in Copenhagen, Denmark, and Christchurch, New Zealand, respectively. Cognitive discrepancy scores were calculated using a novel methodology, with positive values indicating disproportionately more subjective than objective difficulties (i.e., "sensitivity") and negative values indicating more objective than subjective impairments (i.e., "stoicism").

RESULTS

In the Danish partially remitted patient sample, greater 'sensitivity' was associated with more subsyndromal depression severity (standardized Beta (std. β )= 0.4, p < 0.01)), illness duration (std. β = 0.4, p < 0.01), and younger age (std. β = 0.6, p < 0.001). This association was replicated in the New Zealand sample of more symptomatic patients (p-values ≤ 0.05).

LIMITATIONS

The cross-sectional design hampered causal inferences. We had obtained different measures of objective and subjective cognition from the two studies.

CONCLUSIONS

Patients with more depressive symptoms and younger age overreported cognitive impairments across all illness states. The use of an objective cognition screener thus seems particularly relevant for these patients to assess whether subjective complaints are accompanied by measurable cognitive deficits.

Structural changes in the hippocampus as a biomarker for cognitive improvements in neuropsychiatric disorders: A systematic review

Cognitive impairments are a core feature of several neuropsychiatric disorders. A common biomarker for pro-cognitive effects may provide a much-needed tool to select amongst candidate treatments targeting cognition. The hippocampus is a promising biomarker for target-engagement due to the illness-associated morphological hippocampal changes across unipolar disorder (UD), bipolar disorder (BD) and schizophrenia (SCZ). Following the PRISMA guidelines, we searched PubMed and Embase, for clinical trials targeting cognition across neuropsychiatric disorders, with longitudinal structural magnetic resonance imaging (MRI) measures of the hippocampus. Five randomized and three open-label trials were included. Hippocampal volume increases were associated with treatment-related cognitive improvement following treatment with erythropoietin across UD, BD and SCZ, lithium treatment in BD and aerobic exercise in SCZ. Conversely, an exercise intervention in UD showed no effect on hippocampal volume or cognition. Together, these observations point to hippocampal volume change as a putative biomarker-model for cognitive improvement. Future cognition trials are encouraged to include MRI assessments pre- and post-treatment to assess the validity of hippocampal changes as a biomarker for pro-cognitive effects.

Is there a relationship between depression with anxious distress DSM-5 specifier and bipolarity? A multicenter cohort study on patients with unipolar, bipolar I and II disorders

BACKGROUND

To estimate the prevalence of DSM-5 anxious distress specifier (ADS) in depressed patients with major depressive disorder (MDD) or bipolar I or II disorder (BD), and to compare socio-demographic and clinical characteristics, and response to naturalistic short-term treatment between ADS and non-ADS group.

METHODS

241 outpatients with a major depressive episode (MDE) were consecutively recruited. Outcome were remission (HDRS₂₁ total score < 7), response (≥50% reduction of baseline HDRS₂₁) and improvement (CGI-i score ≤ 2) after 12 weeks of treatment sustained for 4 weeks.

RESULTS

ADS was more frequent in BD than in MDD (respectively, 66.9% and 51.2%, χ² = 6.1, p = 0.013). Compared with those non-ADS, patients with ADS had more severe depressive (respectively, HDRS₂₁ total score 20.0 ± 4.4 and 18.6 ± 3.9, t-test = 2.67, p = 0.008) and mania symptoms (respectively, Y-MRS total score 2.2 ± 2.9 and 1.3 ± 2.3, M-W-test = 2.86; p = 0.004) at intake, a higher rate of BD family history (respectively, 35.2% and 22.2%, Χ²-test 10.4, p = 0.004) and more previous hypomanic episodes (respectively, (median (range) 0 (0-20) and 0 (0-15), MW-test = 2.39 p = 0.017). In the MDD group, patients with ADS had higher scores on hyperthymic temperament and mania symptoms (Y-MRS total score (median (range) 2.2 (0-26) and 0 (0-11), respectively, M-W test 2.071, p = 0.038). ADS and no-ADS patients did not significantly differ on outcome measures.

LIMITATIONS

The observational nature of the study and the absence of blinding in outcome assessment.

CONCLUSIONS

ADS is the most common DSM-5 specifier for MDE, is more frequent in BD and need a personalized treatment with moderate use of antidepressants, mostly tricyclic.

Vascular endothelial growth factor plasma levels in depression and following electroconvulsive therapy

Both animal and human studies have implicated the neurotrophic and angiogenic mediator vascular endothelial growth factor (VEGF) in depression, with meta-analyses, indicating that protein levels are raised in patients with depression. In line with this, we have previously shown that VEGFA mRNA levels are higher in whole blood from patients with depression compared to controls, in particular in patients with psychotic unipolar depression, and that treatment with electroconvulsive therapy (ECT) alters VEGFA mRNA levels. The aim of the present study was, therefore, to extend this previous work by assessing plasma VEGF protein levels in patients with depression compared to healthy controls, and in patients following treatment with ECT. We found that there was no difference between controls and patients with depression with regard to plasma VEGF (p = 0.59), and that VEGF levels were unaltered by ECT (p = 0.09) after correction for potential covariates. We found no correlation between VEGF protein and mRNA levels. Within the subgroup of patients receiving treatment with bitemporal ECT (n = 34), we identified a moderate negative correlation (ρ = - 0.54, p = 0.001) between the change in VEGF and the change in depression severity following treatment; however, no other association between VEGF and mood, responder/remitter status, polarity of depression, or presence of psychosis were found. Overall, our results indicate that the measurement of VEGF protein is not a useful marker for depression or response to treatment, and suggest that the measurement of VEGFA mRNA may prove more useful.

Differential clinical characteristics and possible predictors of bipolarity in a sample of unipolar and bipolar inpatients

Major affective conditions including both unipolar (UD) and bipolar disorders (BD) are associated with significant disability throughout the life course. We aimed to investigate the most relevant socio-demographic/clinical differences between UD and BD subjects. Our sample included 180 inpatients, of which 82 (45.5%) participants were diagnosed with UD and 98 (54.5%) with BD. Relative to UD patients, BD individuals were more likely to report prior psychoactive medications, lifetime psychotic symptoms, nicotine abuse, a reduced ability to provide to their needs, gambling behavior, and fewer nonsuicidal self-harm episodes. Moreover, BD patients were more likely to report severe side effects related to medications, a younger age at illness onset and first hospitalization, higher illness episodes, and longer illness duration in years than UD subjects. In a multivariate logistic analysis accounting for age, gender, and socio-demographic characteristics, a significant positive contribution to bipolarity was found only for higher lifetime psychotic symptoms (β = 1.178; p ≤ .05) and number of illness episodes (β = .155; p ≤ .05). The present findings suggest that specific clinical factors may be used in order to better distinguish between UD and BD subgroups. Further studies are required to replicate these findings in larger samples.

Erythropoietin as an add-on treatment for cognitive side effects of electroconvulsive therapy: a study protocol for a randomized controlled trial

Background

Electroconvulsive therapy (ECT) is the most effective treatment for severe depression, but its use is impeded by its cognitive side effects. Novel treatments that can counteract these side effects may therefore improve current treatment strategies for depression. The present randomized trial investigates (1) whether short-term add-on treatment with erythropoietin (EPO) can reduce the cognitive side -effects of ECT and (2) whether such effects are long-lasting. Further, structural and functional magnetic resonance imaging (MRI) will be used to explore the neural underpinnings of such beneficial effects of EPO. Finally, the trial examines whether potential protective effects of EPO on cognition are accompanied by changes in markers of oxidative stress, inflammation, and neuroplasticity.

Methods/design

The trial has a double-blind, randomized, placebo-controlled, parallel group design. Patients with unipolar or bipolar disorder with current moderate to severe depression referred to ECT (N = 52) are randomized to receive four high-dose infusions of EPO (40,000 IU/ml) or placebo (saline). The first EPO/saline infusion is administered within 24 h before the first ECT. The following three infusions are administered at weekly intervals immediately after ECT sessions 1, 4, and 7. Cognition assessments are conducted at baseline, after the final EPO/saline infusion (3 days after eight ECT sessions), and at a 3 months follow-up after ECT treatment completion. The neuronal substrates for potential cognitive benefits of EPO are investigated with structural and functional MRI after the final EPO/saline infusion. The primary outcome is change from baseline to after EPO treatment (3 days after eight ECT sessions) in a cognitive composite score spanning attention, psychomotor speed, and executive functions. With a sample size of N = 52 (n = 26 per group), we have ≥ 80% power to detect a clinically relevant between-group difference in the primary outcome measure at an alpha level of 5% (two-sided test). Behavioral, mood, and blood-biomarker data will be analyzed using repeated measures analysis of covariance. Functional MRI data will be preprocessed and analyzed using the FMRIB Software Library.

Discussion

If EPO is found to reduce the cognitive side effects of ECT, this could have important implications for future treatment strategies for depression and for the scientific understanding of the neurobiological etiology of cognitive dysfunction in patients treated with ECT.

Trial registration

ClinicalTrials.gov, NCT03339596. Registered on 10 November 2017.

Electronic supplementary material

The online version of this article (10.1186/s13063-018-2627-2) contains supplementary material, which is available to authorized users.

Systematic review of randomized controlled trials of candidate treatments for cognitive impairment in depression and methodological challenges in the field

Cognitive impairment is a core feature of Major Depressive Disorder (MDD) but treatments targeting cognition are lacking. Numerous pre-clinical and clinical studies have investigated potential cognition treatments, but overall the evidence is conflicting. We conducted a systematic search following the PRISMA guidelines on PubMed and PsychInfo to evaluate the extant evidence and methodological challenges in randomized controlled trials (RCTs) of biological, psychological and behavioural candidate treatments targeting cognition in MDD. Inclusion criteria were RCTs with a placebo control assessing potential pro-cognitive effects of candidate treatments in MDD. Two independent authors reviewed the studies and assessed their risk of bias with the Cochrane Collaboration׳s Risk of Bias tool. Twenty-eight eligible studies (24 biological and four psychological or behavioural studies) were identified. Cognition was the primary treatment target in ten (36%) trials and an additional treatment outcome together with mood symptoms in 18 (64%) trials. The risk of bias was high or unclear in 93% of trials due to potential selective outcome reporting or 'pseudospecificity' (unspecific cognitive improvement due to reduced depression severity), and/or insufficient details on how the allocation sequence was generated or how blinding was maintained. Several promising treatments were identified, including vortioxetine, erythropoietin, transcranial direct current stimulation and cognitive remediation. However, several common methodological challenges may impede advances in the field. In particular, future trials should select one cognitive composite score as primary outcome, screen for cognitive impairment before inclusion of participants and address 'pseudospecificity' issues. Together, these strategies may improve the success of future cognition trials in MDD.

The effect of second-generation antipsychotic drugs on sleep parameters in patients with unipolar or bipolar disorder

Sleep disturbances predominantly take the form of insomnia in patients with unipolar disorder, while patients with bipolar disorder show a decreased need for sleep. Sleep impairment in these patients is a risk factor for the development of a major depressive episode and suicidal behavior. Administration of second-generation antipsychotics (SGAs) olanzapine, quetiapine, and ziprasidone as augmentation therapy or monotherapy to unipolar and bipolar disorder patients, respectively, has been shown to improve sleep continuity and sleep architecture. Thus, their use by these patients could ameliorate their sleep disorder.

Impaired down-regulation of negative emotion in self-referent social situations in bipolar disorder: A pilot study of a novel experimental paradigm

Emotion dysregulation is a core feature of bipolar disorder (BD) that persists into periods of remission. Neuroimaging studies show aberrant neural responses during emotion regulation (ER) in patients with BD relative to healthy controls, but behavioural evidence for ER deficits is sparse and conflicting. This study aimed to explore ER in BD using a novel, personally relevant experimental paradigm. Twenty patients with BD and 20 patients with unipolar disorder (UD), in full or partial remission, and 20 healthy controls were given a novel computerised test. Participants were instructed to react naturally or dampen their emotional response to positive and negative social scenarios and associated self-beliefs. They were also given an established experimental task for comparison, involving reappraisal of negative affective picture stimuli, as well as a questionnaire of habitual ER strategies. BD patients showed reduced ability to down-regulate emotional responses in negative, but not positive, social scenarios relative to healthy controls and UD patients. In contrast, there were no between-group differences in the established ER task or in self-reported habitual reappraisal strategies. Findings highlight the novel social scenario paradigm as a sensitive test for detection of ER difficulties in BD.

Meta-analysis of short- and mid-term efficacy of ketamine in unipolar and bipolar depression

Among treatments currently assessed in major depression, ketamine, has been proposed of great interest, especially because of its very rapid action. However, the time-course of the antidepressive action of ketamine remained unclear. In the present meta-analysis, we provided a clear and objective view regarding the putative antidepressive effect of ketamine and its time-course. We searched the MEDLINE and PsycINFO databases through December 2013, without limits on year of publication, using the key words ketamine and synonyms for mood disorder or episode. Six randomized, double-blind and placebo-controlled trials of ketamine in major depression (n=103 patients) were thus identified. Authors were contacted and they all provided original data necessary for this meta-analysis. Standardized mean differences (SMD) were calculated between the depression scores in ketamine and placebo groups at days 1, 2, 3-4, 7 and 14. Ketamine showed an overall antidepressive efficacy from day 1 to day 7. However, the maintenance of its efficacy over time failed to reach significance in bipolar depression after day 3-4. Significant SMDs were not explained by demographic or clinical characteristics of included samples. The present meta-analysis provides a high level of evidence that ketamine has a rapid antidepressive action during one week, especially in unipolar disorder.

Electronic monitoring of psychomotor activity as a supplementary objective measure of depression severity

BACKGROUND

Rating scales used to assess the severity of depression e.g. the Hamilton Depression Rating Scale 17-item (HDRS-17) partly rely on the patient's subjective experience and reporting. Such subjective measures tend to have low reliability and adding objective measures to complement the assessment of depression severity would be a major step forward.

AIMS

To investigate correlations between electronic monitoring of psychomotor activity and severity of depression according to HDRS-17.

METHODS

A total of 36 patients with unipolar disorder (n = 18) or bipolar disorder (n = 18) and 31 healthy control persons aged 18-60 years were included. Psychomotor activity was measured using a combined heart rate and movement sensor device (Actiheart) for 3 consecutive days, 24 h a day.

RESULTS

We found that sleeping heart rate (beats/min) correlated with HDRS-17 in both patients with unipolar disorder and bipolar disorder (unadjusted model: B = 0.46, 95% CI 0.037-0.89, P = 0.034). In contrast, correlations between activity energy expenditure (kJ/kg/day), cardio-respiratory fitness (mlO2/min/kg) and HDRS-17 were non-significant.

CONCLUSIONS

These results suggest that measuring sleeping heart rate in non-experimental daily life could be an objective supplementary method to measure the severity of depression and perhaps indicate presence of insomnia.

Predictive value of baseline resistance in early response to antidepressants

BACKGROUND

Major Depressive Disorder (MDD) is the 3rd source for burden worldwide according to the World Health Organization (WHO). This comes partly from unsatisfactory response rates after usual treatment, highlighting the need for early indicators such as early improvement of depressive symptoms to adapt treatment strategies, especially for severe inpatients. Thus our objective was to assess the predictive value of baseline partial resistance in early antidepressant response (EAR), hypothesizing that previous treatment failures would decrease the probability of early response.

METHODS

We included 122 consecutive inpatients with current unipolar MDE. The Mini-Neuropsychiatric Interview was used to ascertain DSM-IV diagnoses of MDD as well as psychiatric comorbidities, and to exclude patients with a history of bipolar disorder. A specifically designed questionnaire was used to collect data on previous treatment trials for the current episode so as to generate scores on the five existing methods for quantifying treatment resistance. We prospectively assessed EAR, defined as a 50% decrease in MADRS after 14 days of steady regimen of antidepressant.

RESULTS

In the per protocol sample (N=76), multivariate analyses showed that psychotic features at baseline remained an independent predictor of absence of EAR (p<.01), unlike baseline partial resistance, which may rather be associated with a lack of any improvement.

LIMITATIONS

Lack of data about further response and non-randomized treatment allocation.

CONCLUSION

Available methods for quantifying treatment resistance are heterogeneous and do not predict short-term response among severely depressed inpatients, despite potential usefulness in predicting a lack of early improvement.