Antidepressant treatment outcomes in patients with and without comorbid physical or psychiatric disorders: A systematic review and meta-analysis

Therapeutic modulation of the kynurenine pathway in severe mental illness and comorbidities: A potential role for serotonergic psychedelics

Mounting evidence points towards a crucial role of the kynurenine pathway (KP) in the altered gut-brain axis (GBA) balance in severe mental illness (SMI, namely depression, bipolar disorder, and schizophrenia) and cardiometabolic comorbidities. Preliminary evidence shows that serotonergic psychedelics and their analogues may hold therapeutic potential in addressing the altered KP in the dysregulated GBA in SMI and comorbidities. In fact, aside from their effects on mood, psychedelics elicit therapeutic improvement in preclinical models of obesity, metabolic syndrome, and vascular inflammation, which are highly comorbid with SMI. Here, we review the literature on the therapeutic modulation of the KP in the dysregulated GBA in SMI and comorbidities, and the potential application of psychedelics to address the altered KP in the brain and systemic dysfunction underlying SMI and comorbidities. Psychedelics might therapeutically modulate the KP in the altered GBA in SMI and comorbidities either directly, via altering the metabolic pathway by influencing the rate-limiting enzymes of the KP and affecting the levels of available tryptophan, or indirectly, by affecting the gut microbiome, gut metabolome, metabolism, and the immune system. Despite promising preliminary evidence, the mechanisms and outcomes of the KP modulation with psychedelics in SMI and systemic comorbidities remain largely unknown and require further investigation. Several concerns are discussed surrounding the potential side effects of this approach in specific cohorts of individuals with SMI and systemic comorbidities.

Comparative effectiveness of selective serotonin reuptake inhibitors (SSRIs) for depression in 43,061 older adults with chronic somatic diseases: A Danish target trial emulation study

OBJECTIVE

To investigate the comparative effectiveness of commonly used selective serotonin reuptake inhibitors (SSRIs) for comorbid depression in older adults with chronic somatic diseases by applying a target-trial-emulation framework.

METHODS

Danish target-trial-emulation study including 43,061 individuals aged ≥65 years (54.1% females, mean age 77.8 years) with a first redeemed prescription for depression with sertraline (n = 6673), escitalopram (n = 7104) or citalopram (n = 29,284) in 2006-2017. Individuals had cancer, cardiovascular diseases (CVD), chronic-obstructive-pulmonary-disease (COPD)/asthma, diabetes, neurodegenerative disorders, or osteoporosis. Outcomes were treatment switching, combination/augmentation, psychiatric hospital contact for depression, and any psychiatric in-patient care. Follow-up was one year and adjusted Cox regression analyses calculated hazard rate ratios (HRR) within each somatic disease.

RESULTS

Across all six disease groups and four outcomes, we found that citalopram use, compared with sertraline, was associated with lower risks in several analyses, with statistically significant results in cancer, CVD, COPD/asthma, and diabetes (e.g., HRRs for psychiatric hospital contacts for depression/any psychiatric in-patient care ranging between 0.47 and 0.61). For escitalopram, compared with sertraline, some analyses indicated poorer outcomes with significantly higher risks for combination/augmentation treatment (HRRs ranging between 1.15 and 1.40).

CONCLUSIONS

Although observational studies are prone to confounding, these findings indicate clinically relevant differences between the SSRIs, with better outcomes in citalopram users and poorer outcomes in escitalopram users than sertraline, urging the need for clinical studies in this vulnerable patient population.

Precision targeting in prediction for rTMS clinical outcome in depression: what about sgACC lateralization, metabolic connectivity, and the potential role of the cerebellum?

Predicting clinical response to repetitive transcranial magnetic stimulation (rTMS) in medication-resistant depression (MRD) has gained great importance in recent years. Mainly, the right subgenual anterior cingulate cortex (sgACC) functional connectivity has been put forward as biomarker in relation to rTMS clinical outcome. Even though the left and right sgACC may have different neurobiological functions, little is known about the possible lateralized predictive role of the sgACC in rTMS clinical outcome. In 43 right-handed antidepressant-free MRD patients, we applied a searchlight-based interregional covariance connectivity approach using the baseline 18FDG-PET scan-collected from two previous high-frequency (HF)-rTMS treatment studies delivering stimulation to the left dorsolateral prefrontal cortex (DLPFC)-and investigated whether unilateral or bilateral sgACC glucose metabolism at baseline would result in different predictive metabolic connectivity patterns. Regardless of sgACC lateralization, the weaker the sgACC seed-based baseline metabolic functional connections with the (left anterior) cerebellar areas, the significantly better the clinical outcome. However, the seed diameter seems to be crucial. Similar significant findings on sgACC metabolic connectivity with the left anterior cerebellum, also unrelated to sgACC lateralization, in relation to clinical outcome were observed when using the HCPex atlas. Although we could not substantiate that specifically right sgACC metabolic connectivity would predict HF-rTMS clinical outcome, our findings suggest considering the entire sgACC in functional connectivity predictions. Given that the interregional covariance connectivity results were significant only when using the Beck Depression Inventory (BDI-II) and not with the Hamilton Depression Rating Scale (HDRS), our sgACC metabolic connectivity observations also suggest the possible involvement of the (left) anterior cerebellum involved in higher-order cognitive processing as part of this predictive value.

History repeating: guidelines to address common problems in psychedelic science

Research in the last decade has expressed considerable optimism about the clinical potential of psychedelics for the treatment of mental disorders. This optimism is reflected in an increase in research papers, investments by pharmaceutical companies, patents, media coverage, as well as political and legislative changes. However, psychedelic science is facing serious challenges that threaten the validity of core findings and raise doubt regarding clinical efficacy and safety. In this paper, we introduce the 10 most pressing challenges, grouped into easy, moderate, and hard problems. We show how these problems threaten internal validity (treatment effects are due to factors unrelated to the treatment), external validity (lack of generalizability), construct validity (unclear working mechanism), or statistical conclusion validity (conclusions do not follow from the data and methods). These problems tend to co-occur in psychedelic studies, limiting conclusions that can be drawn about the safety and efficacy of psychedelic therapy. We provide a roadmap for tackling these challenges and share a checklist that researchers, journalists, funders, policymakers, and other stakeholders can use to assess the quality of psychedelic science. Addressing today's problems is necessary to find out whether the optimism regarding the therapeutic potential of psychedelics has been warranted and to avoid history repeating itself.

Combination of Shengmai San and Radix puerariae ameliorates depression-like symptoms in diabetic rats at the nexus of PI3K/BDNF/SYN protein expression

BACKGROUND

Hyperglycemia is a characteristic feature of diabetes that often results in neuropsychological complications such as depression. Diabetic individuals are more vulnerable to experience depression compared to the normal population. Thus, novel treatment approaches are required to reduce depressive symptoms among diabetic individuals. Traditional Chinese medicines (TCMs) such as Shengmai San (SMS) and Radix puerariae (R) are usually widely used to treat ailments such as neurological complications since ancient time.

METHODS

In this study, SMS was combined with R to prepare an R-SMS formulation and screened for their antidepressant activity in diabetic rats. The antidepressant potential of the prepared combination was evaluated behaviorally using open field test, novelty-induced hypophagia, and forced swim test in diabetic rats with biochemical and protein expression (PI3K, BDNF [brain-derived neurotrophic factor], and SYN [presynaptic vesicle protein]) analysis.

RESULTS

Diabetic rats (streptozotocin, 45 mg/kg) showed elevated fasting blood glucose (FBG) >12 mM with depressive symptoms throughout the study. Treatment with R-SMS (0.5, 1.5, and 4.5 g/kg) significantly reverted depressive symptoms in diabetic rats as evinced by significantly (p < 0.05) reduced immobility time with an increased tendency to eat food in a novel environment. Treatment with R-SMS also significantly increased the protein expression of PI3K, BDNF, and SYN protein, which play a crucial role in depression.

CONCLUSION

This study showed that R-SMS formulation antagonized depressive symptoms in diabetic rats; thus, this formulation might be studied further to develop as an antidepressant.

Reliability and validity of the difficult to treat depression questionnaire (DTDQ)

It has recently been recommended that treatment resistant depression be reconceptualized and renamed as difficult to treat depression (DTD). A consensus statement by an expert panel identified multiple variables associated with DTD and emphasized the importance of conducting a comprehensive evaluation of patients to identify predictors of inadequate treatment response. For practical reasons, it would be desirable to develop a self-report scale that can be incorporated into clinical practice that identifies patient, clinical, and treatment risk factors for DTD. Nine hundred twenty depressed patients completed the Difficult to Treat Depression Questionnaire (DTDQ). A subset of patients completed the scale a second time and completed the Remission from Depression Questionnaire at admission and discharge from a partial hospital program. The DTDQ demonstrated excellent internal consistency and test-retest reliability. Both the total DTDQ and the number of prior failed medication trials, the metric primarily relied upon to classify treatment resistant depression, predicted outcome. However, the DTDQ continued to be significantly associated with outcome after controlling for the number of failed trials, whereas the number of failed trials did not predict outcome after controlling for DTDQ scores. The DTDQ is a reliable and valid measure of the recently discussed concept of DTD.

Characterisation of medication side effects in patients with mostly resistant depression in a real-world setting

OBJECTIVES

This study aimed to identify factors associated with side effects of psychotropic drugs in a real-world setting enriched with treatment-resistant depression (TRD) patients.

METHODS

A total of 1410 depressed patients were treated in a naturalistic setting. Side effects were measured with the Udvalg for Kliniske Undersogelser Side Effect Rating Scale (UKU); the total score and UKU subscales were considered. Clinical-demographic variables were tested for association with side effects in univariate and then multivariate analyses.

RESULTS

Total, psychic and neurological side effects were associated with depressive symptom severity, while autonomic side effects were higher in those with somatic comorbidities and other side effects were lower in patients receiving trazodone. In multivariate analyses, depressive symptom severity was associated with psychic and total side effects, while generalised anxiety disorder (GAD) with neurological side effects and somatic comorbidities remained associated with autonomic side effects. Trazodone was associated with lower side effects and with augmentation treatments. Augmentation therapies showed opposite effects depending on response status, i.e. increased or decreased the risk of side effects in responders and non-responders/resistant patients, respectively.

CONCLUSIONS

Psychic side effects may be difficult to distinguish from depressive symptoms and factors associated with different types of side effects are heterogeneous and likely interacting.

Lateralized subgenual ACC metabolic connectivity patterns in refractory melancholic depression: does it matter?

Although treatment resistance to antidepressant pharmacotherapy is quite common, the phenomenon of refractory major depressive disorder (rMDD) is not well understood. Nevertheless, the metabolic activity of the subgenual anterior cingulate cortex (sgACC) has been put forward as a possible metabolic biomarker of clinical prediction and response, albeit sgACC lateralization differences in functional connectivity have not yet been extensively examined. Also not in the refractory depressed state. To examine sgACC lateralization differences in metabolic connectivity, we recruited 43 right-handed antidepressant-free unipolar melancholic rMDD patients and 32 right-handed healthy controls to participate in this 18FDG PET study and developed a searchlight-based interregional covariance connectivity approach. Compared to non-depressed individuals, sgACC covariance analysis showed stronger metabolic connections with frontolimbic brain regions known to be affected in the depressed state. Furthermore, whereas the left sgACC showed stronger metabolic connections with ventromedial prefrontal cortical regions, implicated in anhedonia, suicidal ideation, and self-referential processes, the right sgACC showed significantly stronger metabolic connections with posterior hippocampal and cerebellar regions, respectively specialized in memory and social processing. Overall, our results substantiate earlier research that the sgACC is a metabolic key player when clinically depressed and that distinct lateralized sgACC metabolic connectivity patterns are present.

Efficacy and safety of vortioxetine in treatment of patients with major depressive disorder and common co-morbid physical illness

BACKGROUND

The multimodal antidepressant vortioxetine is effective in reducing somatic symptoms in patients with major depressive disorder (MDD), but little is known about its effects in reducing depressive symptoms in patients with common comorbid physical illnesses.

METHODS

This was a pooled analysis of 13 randomized, placebo-controlled trials which evaluated the efficacy (using the Montgomery-Åsberg Depression Rating Scale [MADRS]) and safety of vortioxetine (5-20 mg/day) in adult patients with MDD. We evaluated stable somatic comorbid conditions that were verified by a diagnosis and had sufficient database representation.

RESULTS

Of the 5982 patients included in the database, 963 (16.1%) patients had a diagnosis of cardiovascular disease, 152 (2.5%) had diabetes mellitus and 26 (0.4%) had chronic obstructive pulmonary disorder (COPD). At Week 8, adjusted mean[95%CI] treatment differences (vortioxetine vs. placebo) on MADRS total scores were -2.7[-4.2, -1.3] (p = 0.0002) points for the cardiovascular disease, -4.0[-7.7, -0.4] (p = 0.03) for the diabetes, and -6.2[-21.3, 8.9] (p = 0.36) for the COPD groups. The rate and pattern of adverse events were similar across the sub-groups with comorbidities and was consistent with that expected for vortioxetine treatment.

LIMITATIONS

The primary studies were not designed to investigate the relationship between vortioxetine and comorbidities, nor were the post hoc analyses powered to detect group differences.

CONCLUSIONS

Patients with MDD and comorbid cardiovascular disease or diabetes respond to vortioxetine in a similar way to the broader MDD population. Vortioxetine was generally safe and well tolerated and without unexpected adverse events in these subpopulations, most of whom are taking multiple concomitant medications.