Surrogate Markers of Insulin Resistance in Predicting Major Depressive Disorder: Metabolism Metastasizes to the Brain

Genetically predicted brain cortical structure mediates the causality between insulin resistance and cognitive impairment

Background

Insulin resistance is tightly related to cognition; however, the causal association between them remains a matter of debate. Our investigation aims to establish the causal relationship and direction between insulin resistance and cognition, while also quantifying the mediating role of brain cortical structure in this association.

Methods

The publicly available data sources for insulin resistance (fasting insulin, homeostasis model assessment beta-cell function and homeostasis model assessment insulin resistance, proinsulin), brain cortical structure, and cognitive phenotypes (visual memory, reaction time) were obtained from the MAGIC, ENIGMA, and UK Biobank datasets, respectively. We first conducted a bidirectional two-sample Mendelian randomization (MR) analysis to examine the susceptibility of insulin resistance on cognitive phenotypes. Additionally, we applied a two-step MR to assess the mediating role of cortical surficial area and thickness in the pathway from insulin resistance to cognitive impairment. The primary Inverse-variance weighted, accompanied by robust sensitivity analysis, was implemented to explore and verify our findings. The reverse MR analysis was also performed to evaluate the causal effect of cognition on insulin resistance and brain cortical structure.

Results

This study identified genetically determined elevated level of proinsulin increased reaction time (beta=0.03, 95% confidence interval [95%CI]=0.01 to 0.05, p=0.005), while decreasing the surface area of rostral middle frontal (beta=-49.28, 95%CI=-86.30 to -12.27, p=0.009). The surface area of the rostral middle frontal mediated 20.97% (95%CI=1.44% to 40.49%) of the total effect of proinsulin on reaction time. No evidence of heterogeneity, pleiotropy, or reverse causality was observed.

Conclusions

Briefly, our study noticed that elevated level of insulin resistance adversely affected cognition, with a partial mediation effect through alterations in brain cortical structure.

The Search for Consistency in Residual Symptoms in Major Depressive Disorder: A Narrative Review

Residual symptoms are prevalent in major depressive disorder (MDD), encompassing a wide spectrum of symptoms such as sleep disturbances, changes in weight and appetite, cognitive impairment, and anxiety. These symptoms consistently impair daily functioning, diminish quality of life, and forecast disease relapse. Despite their clinical significance, residual symptoms lack a unified definition, potentially leading to confusion with treatment-emergent symptoms and ambiguity across studies, thereby hindering the generalizability of research findings. While some research identifies insomnia and mood disturbances as critical indicators, other studies emphasize different symptoms or find no significant correlation. Inconsistencies in defining residual symptoms, as well as methodological differences across studies, contribute to these conflicting results. While clinicians focus on alleviating negative symptoms to improve functional status, patients often prioritize achieving positive affect and overall well-being as essential components of successful treatment. It necessitates a comprehensive approach to patient care in depression. This review explores the phenomenon of residual symptoms in MDD, focusing on the ambiguity in definitions, clinical characteristics, and their impact on long-term outcomes. The lack of a standardized regulatory or academic definition for residual symptoms leads to varied interpretations among clinicians, underscoring the need for standardized terminology to guide effective treatment strategies and future research.

Triglyceride-glucose index as a potential predictor of major adverse cardiovascular and cerebrovascular events in patients with coronary heart disease complicated with depression

Background

Triglyceride-glucose (TyG) index is a surrogate marker of insulin resistance and metabolic abnormalities, which is closely related to the prognosis of a variety of diseases. Patients with both CHD and depression have a higher risk of major adverse cardiovascular and cerebrovascular events (MACCE) and worse outcome. TyG index may be able to predict the adverse prognosis of this special population.

Methods

The retrospective cohort study involved 596 patients with both CHD and depression between June 2013 and December 2023. The primary outcome endpoint was the occurrence of MACCE, including all-cause death, stroke, MI and emergent coronary revascularization. The receiver operating characteristic (ROC) curve, Cox regression analysis, Kaplan-Meier survival analysis, and restricted cubic spline (RCS) analysis were used to assess the correlation between TyG index and MACCE risk of in patients with CHD complicated with depression.

Results

With a median follow-up of 31 (15-62) months, MACCE occurred in 281(47.15%) patients. The area under the ROC curve of TyG index predicting the risk of MACCE was 0.765(0.726-0.804) (P<0.01). Patients in the high TyG index group(69.73%) had a significantly higher risk of developing MACCE than those in the low TyG index group(23.63%) (P<0.01). The multifactorial RCS model showed a nonlinear correlation (nonlinear P<0.01, overall P<0.01), with a critical value of 8.80 for the TyG index to predict the occurrence of MACCE. The TyG index was able to further improve the predictive accuracy of MACCE.

Conclusions

TyG index is a potential predictor of the risk of MACCE in patients with CHD complicated with depression.

Impacts of metabolic disruption, body mass index and inflammation on cognitive function in post-COVID-19 condition: a randomized controlled trial on vortioxetine

BACKGROUND

Post-COVID-19 Condition (PCC), as defined by the World Health Organization (WHO), currently lacks any regulatory-approved treatments and is characterized by persistent and debilitating cognitive impairment and mood symptoms. Additionally, metabolic dysfunction, chronic inflammation and the associated risks of elevated body mass index (BMI) have been reported. In this study, we aim to investigate the efficacy of vortioxetine in improving cognitive deficits in individuals with PCC, accounting for the interaction of metabolic dysfunction, elevated inflammation and BMI.

METHODS

This is a post-hoc analysis of an 8-week randomized, double-blind, placebo-controlled trial that was conducted among adults aged 18 years and older living in Canada who were experiencing WHO-defined PCC symptoms. The recruitment of participants began in November 2021 and concluded in January 2023. A total of 200 individuals were enrolled, where 147 were randomized in a 1:1 ratio to receive either vortioxetine (5-20 mg, n = 73) or placebo (n = 74) for daily treatment under double-blind conditions. The primary outcome measure was the change in the Digit Symbol Substitution Test (DSST) score from baseline to endpoint.

RESULTS

Our findings showed significant effects for time (χ2 = 7.771, p = 0.005), treatment (χ2 = 7.583, p = 0.006) and the treatment x time x CRP x TG-HDL x BMI interaction (χ2 = 11.967, p = 0.018) on cognitive function. Moreover, the between-group analysis showed a significant improvement with vortioxetine at endpoint (mean difference = 0.621, SEM = 0.313, p = 0.047).

CONCLUSION

Overall, vortioxetine demonstrated significant improvements in cognitive deficits among individuals with baseline markers of metabolic dysfunction, elevated inflammation and higher BMI at endpoint as compared to placebo.

TRIAL REGISTRATION

NCT05047952 (ClinicalTrials.gov; Registration Date: September 17, 2021).

Study on the correlation between the level of insulin resistance and changes in the degree of cerebral atherosclerosis in non-diabetic patients

BACKGROUND

Cerebral infarction is a health problem of global concern and brings a particular burden to medical treatment.

OBJECTIVE

To analyze the correlation between insulin resistance (IR) levels and changes in cerebral atherosclerosis (AS) degree in non-diabetic patients with cerebral infarction.

METHODS

A total of 134 non-diabetic patients with cerebral infarction who visited the Department of Neurology of our hospital from May 2019 to October 2020 were selected and underwent MRA/CTA (Magnetic resonance angiography/Computed tomography angiography) of cerebral arteries to refine the cerebrovascular imaging data, and according to the results of cerebral AS load, the patients were divided into mild AS group and severe AS group, and the insulin resistance index was calculated with HOMA-IR (homeostasis model assessment of insulin resistance) to evaluate the IR level and HOMA-IR was compared between the two groups. Spearman correlation was used to analyze the correlation between the levels of IR in patients and the changes in cerebral AS load.

RESULTS

54 individuals had severe AS and 80 patients had mild AS, according to an MRA/CTA of the cerebral arteries. There was a significant difference (P< 0.05) in HOMA-IR between the difficult and gentle AS groups. A significant link between HOMA-IR and the severity of cerebral AS in patients was found using Spearman correlation analysis (r= 0.850, P< 0.05).

CONCLUSION

The IR phenomenon was prevalent in non-diabetic patients with cerebral infarction, and the level of IR was closely related to the severity of cerebral AS.

Association between the triglyceride-glucose index and suicidal ideation: A nationwide cross-sectional survey

PURPOSE

This study investigated the relationship between insulin resistance and suicidal ideation.

METHODS

We analyzed the data of 21,350 participants from 4 years of the Korea National Health and Nutrition Examination Survey. The triglyceride-glucose (TyG) index was used to assess insulin resistance, and suicidal ideation was recorded through self-reported questionnaires. We used multivariable logistic regression analysis to ensure the independent association between the TyG index and suicidal ideation.

RESULTS

Approximately 4.3 % of participants had suicidal ideation. The TyG index was significantly associated with suicidal ideation, but only among women. Subgroup analysis in women revealed that the association between the TyG index and suicidal ideation was more remarkable in the low-risk group for suicide.

LIMITATIONS

Causality and the impact of unmeasured confounders were not addressed.

CONCLUSION

The TyG index may help prevent suicide in women via earlier detection of suicidal ideation.

Risk of depression and anxiety disorders according to long-term glycemic variability

BACKGROUND

Poor glycemic control has been linked to psychiatric symptoms. However, studies investigating the relationship between glycemic variability (GV) and depression and anxiety disorders are limited. We investigated the association of GV with depression and anxiety disorders. In addition, the relationship between trends in fasting plasma glucose (FPG) levels and these disorders were explored.

METHODS

We analyzed the National Health Insurance Service-National Sample Cohort database (2002-2013) with 151,814 participants who had at least three health screenings between 2002 and 2010. Visit-to-visit FPG variability was measured as variability independent of the mean (VIM). Depression and anxiety disorders were diagnosed using ICD-10 codes (F41 for anxiety and F32 or F33 for depression) after index date. We analyzed the association between GV and incidences of these disorders using Kaplan-Meier and Cox proportional hazards methods. Trajectory analysis was conducted to explore the relationship between FPG trends and these disorders.

RESULTS

During follow-up, 7166 and 14,149 patients were newly diagnosed with depression and anxiety disorders, respectively. The highest quartile group of FPG-VIM had a greater incidence of depression and anxiety than the lowest quartile group, with adjusted hazard ratios of 1.09 (95 % confidence interval [CI]: 1.02-1.17) and 1.08 (95 % CI: 1.03-1.14). Group with persistent hyperglycemia, identified through trajectory clustering of FPG levels, had a 1.43-fold increased risk of depression compared to those with consistently low FPG levels.

LIMITATIONS

Potential selection bias by including participants with at least three health screenings.

CONCLUSIONS

High GV and persistent hyperglycemia are associated with increased incidence of depression and anxiety disorders.

Treatment-resistant depression: definition, prevalence, detection, management, and investigational interventions

Treatment-resistant depression (TRD) is common and associated with multiple serious public health implications. A consensus definition of TRD with demonstrated predictive utility in terms of clinical decision-making and health outcomes does not currently exist. Instead, a plethora of definitions have been proposed, which vary significantly in their conceptual framework. The absence of a consensus definition hampers precise estimates of the prevalence of TRD, and also belies efforts to identify risk factors, prevention opportunities, and effective interventions. In addition, it results in heterogeneity in clinical practice decision-making, adversely affecting quality of care. The US Food and Drug Administration (FDA) and the European Medicines Agency (EMA) have adopted the most used definition of TRD (i.e., inadequate response to a minimum of two antidepressants despite adequacy of the treatment trial and adherence to treatment). It is currently estimated that at least 30% of persons with depression meet this definition. A significant percentage of persons with TRD are actually pseudo-resistant (e.g., due to inadequacy of treatment trials or non-adherence to treatment). Although multiple sociodemographic, clinical, treatment and contextual factors are known to negatively moderate response in persons with depression, very few factors are regarded as predictive of non-response across multiple modalities of treatment. Intravenous ketamine and intranasal esketamine (co-administered with an antidepressant) are established as efficacious in the management of TRD. Some second-generation antipsychotics (e.g., aripiprazole, brexpiprazole, cariprazine, quetiapine XR) are proven effective as adjunctive treatments to antidepressants in partial responders, but only the olanzapine-fluoxetine combination has been studied in FDA-defined TRD. Repetitive transcranial magnetic stimulation (TMS) is established as effective and FDA-approved for individuals with TRD, with accelerated theta-burst TMS also recently showing efficacy. Electroconvulsive therapy is regarded as an effective acute and maintenance intervention in TRD, with preliminary evidence suggesting non-inferiority to acute intravenous ketamine. Evidence for extending antidepressant trial, medication switching and combining antidepressants is mixed. Manual-based psychotherapies are not established as efficacious on their own in TRD, but offer significant symptomatic relief when added to conventional antidepressants. Digital therapeutics are under study and represent a potential future clinical vista in this population.

The concept of "metabolic jet lag" in the pathophysiology of bipolar disorder: implications for research and clinical care

Bipolar disorder (BD) is a potentially chronic mental disorder marked by recurrent depressive and manic episodes, circadian rhythm disruption, and changes in energetic metabolism. "Metabolic jet lag" refers to a state of shift in circadian patterns of energy homeostasis, affecting neuroendocrine, immune, and adipose tissue function, expressed through behavioral changes such as irregularities in sleep and appetite. Risk factors include genetic variation, mitochondrial dysfunction, lifestyle factors, poor gut microbiome health and abnormalities in hunger, satiety, and hedonistic function. Evidence suggests metabolic jet lag is a core component of BD pathophysiology, as individuals with BD frequently exhibit irregular eating rhythms and circadian desynchronization of their energetic metabolism, which is associated with unfavorable clinical outcomes. Although current diagnostic criteria lack any assessment of eating rhythms, technological advancements including mobile phone applications and ecological momentary assessment allow for the reliable tracking of biological rhythms. Overall, methodological refinement of metabolic jet lag assessment will increase knowledge in this field and stimulate the development of interventions targeting metabolic rhythms, such as time-restricted eating.

The clinical characterization of the adult patient with bipolar disorder aimed at personalization of management

Bipolar disorder is heterogeneous in phenomenology, illness trajectory, and response to treatment. Despite evidence for the efficacy of multimodal-ity interventions, the majority of persons affected by this disorder do not achieve and sustain full syndromal recovery. It is eagerly anticipated that combining datasets across various information sources (e.g., hierarchical "multi-omic" measures, electronic health records), analyzed using advanced computational methods (e.g., machine learning), will inform future diagnosis and treatment selection. In the interim, identifying clinically meaningful subgroups of persons with the disorder having differential response to specific treatments at point-of-care is an empirical priority. This paper endeavours to synthesize salient domains in the clinical characterization of the adult patient with bipolar disorder, with the overarching aim to improve health outcomes by informing patient management and treatment considerations. Extant data indicate that characterizing select domains in bipolar disorder provides actionable information and guides shared decision making. For example, it is robustly established that the presence of mixed features - especially during depressive episodes - and of physical and psychiatric comorbidities informs illness trajectory, response to treatment, and suicide risk. In addition, early environmental exposures (e.g., sexual and physical abuse, emotional neglect) are highly associated with more complicated illness presentations, inviting the need for developmentally-oriented and integrated treatment approaches. There have been significant advances in validating subtypes of bipolar disorder (e.g., bipolar I vs. II disorder), particularly in regard to pharmacological interventions. As with other severe mental disorders, social functioning, interpersonal/family relationships and internalized stigma are domains highly relevant to relapse risk, health outcomes, and quality of life. The elevated standardized mortality ratio for completed suicide and suicidal behaviour in bipolar disorder invites the need for characterization of this domain in all patients. The framework of this paper is to describe all the above salient domains, providing a synthesis of extant literature and recommendations for decision support tools and clinical metrics that can be implemented at point-of-care.

Interventions targeting comorbid depression and overweight/obesity: A systematic review

BACKGROUND

Overweight/obesity and depression are highly co-occurring conditions with shared pathophysiology as well as social and economic determinants. To our knowledge, this is the first systematic review aims to comprehensively synthesize extant literature with a focus on the effectiveness of interventions targeting obesity and depression comorbidity.

METHODS

We searched databases including MEDLINE, ProQuest Central, Web of Science, PsycINFO, Cochrane Library, from inception of the databases until Nov 12, 2021. Articles were included if they reported on the effects of pharmacological, psychological or dietary interventions on comorbid depression and overweight/obesity as their primary or secondary outcome.

RESULTS

Of the 5480 identified records, 19 eligible researches comprising 15 RCTs and 4 uncontrolled longitudinal studies for 3408 participants with comorbid depression and overweight/obesity. The available literature is not sufficient to inform evidence-based treatments targeting obesity and comorbid depression contemporaneously. Notwithstanding, the combination of CBT and lifestyle intervention show efficacy targeting obesity and comorbid depression as do some nutritional supplements, antidepressants and anti-diabetic agents.

LIMITATIONS

The high heterogeneity of various interventions in the included studies may cause a lack of comparability between different studies.

CONCLUSIONS

Concurrent management of depression and overweight/obesity is suggested by available data. There is a pressing need for studies that evaluate the effectiveness in real world samples of persons experiencing multiple co-occurring chronic diseases including but not limited to depression and overweight/obesity.