Association of Insulin Resistance With Depression Severity and Remission Status: Defining a Metabolic Endophenotype of Depression

Dietary live microorganisms and depression-driven mortality in hypertensive patients: NHANES 2005-2018

OBJECTIVE

To investigate the relationship between dietary microorganism intake and mortality risk among hypertensive adults with depression in the United States.

METHODS

This study utilizes data from the 2005-2018 National Health and Nutrition Examination Survey, focusing on individuals with hypertension. The Kaplan-Meier (K-M) curve is employed to preliminarily explore the relationship between dietary microorganism intake, depression, and mortality risk in hypertensive individuals. The Cox proportional hazards model is used for both individual and combined analyses of these relationships. Mediation analysis assesses the mediating effect of depression on the association between dietary microorganisms and mortality, while subgroup and sensitivity analysis evaluates the stability of the model.

RESULTS

This cohort study included 11,602 hypertensive participants (5,904 men and 5,698 women), with 1,201 having depression. During follow-up period, 2,085 died from all causes, 692 due to cardiovascular events. Preliminary analysis using the K-M curve reveals that hypertensive individuals with higher dietary microorganism intake and those without depression have lower mortality risks. Cox proportional hazards model analysis shows that increased dietary microorganism intake is associated with reduced mortality risk in hypertensive individuals (HRALL-cause=0.654, 95%CI: 0.555-0.771; HRCVD-cause:0.675, 95%CI: 0.472,0.967). High intake of diets rich in dietary microorganisms may mitigate the ALL-cause mortality risk of depression in hypertensive populations(HRALL-cause=0.493, 95%CI: 0.256-0.947). Mediation analysis revealed that depression serves as a partial mediator in the process of dietary microorganisms improving the long - term prognosis of the hypertensive population. Results of subgroup analysis and sensitivity analysis showed that the beneficial effect of dietary microorganism intake on prognosis remained stable in most of the hypertensive population.

CONCLUSION

Patients with depression among those suffering from hypertension can reduce the risk of all-cause mortality caused by depression by increasing their intake of dietary microorganisms. This provides clinicians with a new non-pharmacological intervention approach and offers a direction for the optimization of clinical combined treatment regimens.

Correlation between estimated glucose disposal rate and diabetic depression: a population-based study

Background

Emerging evidence has identified a correlation between depression and insulin resistance (IR). This study aims to explore the correlation between estimated glucose disposal rate (eGDR)-a noninvasive and practical measure of IR-and depression in patients with diabetes mellitus (DM).

Methods

In this cross-sectional study, the data from 3,080 adults aged 18 years old or older with DM obtained from NHANES 1999-2018 were analyzed. The correlation between eGDR and depression were examined through multivariate logistic regression, subgroup analyses, restricted cubic spline (RCS) analysis, and interaction tests. Additionally, mediation analysis was conducted to assess whether leukocytes and neutrophils could mediate the effects of eGDR on depression.

Results

Multivariate logistic regression and RCS analyses demonstrate that eGDR was negative linearly correlated with diabetic depression (OR= 0.89; 95% CI: 0.84, 0.95). Patients with DM in Q3 and Q4 of eGDR exhibited a reduced risk of 28% and 54%, respectively, in depression, compared to those in Q1. Subgroup analyses, stratified by variables such as gender, BMI, age, education level, and medical comorbidities, consistently showed a negative correlation. Mediation analysis further indicates that neutrophils and leukocytes accounted for 4.0% and 3.6% of the correlation between eGDR and depression, respectively.

Conclusions

The results of this study demonstrated a statistically significant inverse linear correlation between eGDR and the prevalence of depression in patients with DM, with leukocytes and neutrophils acting as mediating factors in this correlation.

Fasting insulinemia as biomarker of illness relapse in patients with severe mental illness?

Severe Mental Illness (SMI) is often associated with metabolic alteration and/or metabolic syndrome, which may determine an increased mortality due to a further increased cardiovascular risk. The relationship with metabolic syndrome is often bidirectional, resulting in a pathoplastic effect of these dysmetabolisms. Among the several hormones involved, insulin appears to play a key role, albeit not entirely clear. The aim of our real-world cross-sectional observational study is to investigate a set of metabolic biomarkers of illness relapse/recurrence/onset in a cohort of 310 adult SMI inpatients consecutively admitted to the Psychiatry Clinic of the Azienda Ospedaliero Universitaria of Marche, in Ancona (Italy), between February 2021 and February 2024. According to the stepwise multivariate regression model, a higher number of acute episodes per year was positively predicted by the age of illness onset, the lifetime number of suicidal attempts and fasting insulinemia and negatively by the participant's age. A second stepwise multivariate regression model using only the metabolic characteristics as independent variables, found that a higher number of acute episodes per year was predicted positively by the fasting insulinemia and red blood cells and negatively by the abdominal circumference. Overall, our findings could provide practical implications for the treatment and management of SMI patients, emphasizing the importance of monitoring and managing metabolic factors, particularly insulinemia, metabolic syndrome and insulin resistance. Finally, insulinemia could potentially act as metabolic biomarker of illness relapse, though more larger and longitudinal studies should be carried out to confirm these results.

Estimated glucose disposal rate is correlated with increased depression: a population-based study

BACKGROUND

Recent studies have identified a correlation between insulin resistance (IR) and depression. This study aims to explore the correlation between estimated glucose disposal rate (eGDR), a practical and noninvasive measure for assessing IR, and depression in the general population.

METHODS

In this population-based cross-sectional study, data from 28,444 adults aged 18 years old or older in the NHANES during the period from 1999 to 2018 were analyzed. The correlation between eGDR and depression was examined through multivariate logistic regression analyses, subgroup analyses, restricted cubic spline, and interaction tests. Furthermore, a mediation analysis was conducted to elucidate the role of the atherogenic index of plasma (AIP) in mediating the effect of eGDR on depression.

RESULTS

Multivariate logistic regression analysis and restricted cubic splines analysis indicated that eGDR can exhibit a linearly correlation with depression (OR = 0.913; 95% CI: 0.875, 0.953). Subjects in eGDR6-8 and eGDR > 8 groups had a decrease risk of depression as 25.4% and 41.5% than those in the eGDR < 4 group. This negative correlation was more pronounced in those with obesity. Mediation analysis indicated that AIP mediated 9.6% of the correlation between eGDR and depression.

CONCLUSIONS

eGDR was linear negatively correlated with depression, with AIP playing a mediating role. This study provides a novel perspective on the mechanism connecting IR to depression. Managing IR and monitoring AIP may contribute to alleviating depression.

Striatal dopamine gene network moderates the effect of early adversity on the risk for adult psychiatric and cardiometabolic comorbidity

Cardiometabolic and psychiatric disorders often co-exist and share common early life risk factors, such as low birth weight. However, the biological pathways linking early adversity to adult cardiometabolic/psychiatric comorbidity remain unknown. Dopamine (DA) neurotransmission in the striatum is sensitive to early adversity and influences the development of both cardiometabolic and psychiatric diseases. Here we show that a co-expression based polygenic score (ePGS) reflecting individual variations in the expression of the striatal dopamine transporter gene (SLC6A3) network significantly interacts with birth weight to predict psychiatric and cardiometabolic comorbidities in both adults (UK Biobank, N = 225,972) and adolescents (ALSPAC, N = 1188). Decreased birth weight is associated with an increased risk for psychiatric and cardiometabolic comorbidities, but the effect is dependent on a striatal SLC6A3 ePGS, that reflects individual variation in gene expression of genes coexpressed with the SLC6A3 gene in the striatum. Neuroanatomical analyses revealed that SNPs from the striatum SLC6A3 ePGS were significantly associated with prefrontal cortex gray matter density, suggesting a neuroanatomical basis for the link between early adversity and psychiatric and cardiometabolic comorbidity. Our study reveals that psychiatric and cardiometabolic diseases share common developmental pathways and underlying neurobiological mechanisms that includes dopamine signaling in the striatum.

Role of Peripheral and Central Insulin Resistance in Neuropsychiatric Disorders

Insulin acts on different organs, including the brain, which helps it regulate energy metabolism. Insulin signaling plays an important role in the function of different cell types. In this review, we have summarized the key roles of insulin and insulin receptors in healthy brains and in different brain disorders. Insulin signaling, as well as insulin resistance (IR), is a major contributor in the regulation of mood, behavior, and cognition. Recent evidence showed that both peripheral and central insulin resistance play a role in the pathophysiology, clinical presentation, and management of neuropsychiatric disorders like Cognitive Impairment/Dementia, Depression, and Schizophrenia. Many human studies point out Insulin Resistance/Metabolic Syndrome can increase the risk of dementia especially Alzheimer's dementia (AD). IR has been shown to play a role in AD development but also in its progression. This review article discusses the pathophysiological pathways and mechanisms of insulin resistance in major neuropsychiatric disorders. The extent of insulin resistance can be quantified using IR biomarkers like insulin levels, HOMA-IR index, and Triglyceride glucose-body mass index (TyG-BMI) levels. IR has been shown to precede neurodegeneration. Human trials showed current treatment with certain antidiabetic drugs, as well as life style management, like weight loss and exercise for IR, have shown promise in the management of cognitive/neuropsychiatric disorders. This may pave the pathway to the development of new therapeutic approaches to these challenging disorders of dementia and psychiatric diseases. Recent clinical trials are showing some encouraging evidence for these pharmacological and nonpharmacological approaches for IR in psychiatric and cognitive disorders, even though more research is needed to apply this evidence into clinical practice. Early identification and management of IR may help as a strategy to potentially alter neuropsychiatric disorders onset as well as its progression.

The researcher's guide to selecting biomarkers in mental health studies

Clinical mental health researchers may understandably struggle with how to incorporate biological assessments in clinical research. The options are numerous and are described in a vast and complex body of literature. Here we provide guidelines to assist mental health researchers seeking to include biological measures in their studies. Apart from a focus on behavioral outcomes as measured via interviews or questionnaires, we advocate for a focus on biological pathways in clinical trials and epidemiological studies that may help clarify pathophysiology and mechanisms of action, delineate biological subgroups of participants, mediate treatment effects, and inform personalized treatment strategies. With this paper we aim to bridge the gap between clinical and biological mental health research by (1) discussing the clinical relevance, measurement reliability, and feasibility of relevant peripheral biomarkers; (2) addressing five types of biological tissues, namely blood, saliva, urine, stool and hair; and (3) providing information on how to control sources of measurement variability.

Association of METS-IR index with depressive symptoms in US adults: A cross-sectional study

BACKGROUND

An association between insulin resistance (IR) and depression has been identified in recent years. The purpose of this study was to examine the relationship between IR and depression in the general population.

METHODS

The population for this cross-sectional study consisted of adults participating in the National Health and Nutrition Examination Survey (NHANES) between 2005 and 2018. Insulin sensitivity was assessed using the Metabolic Score for IR (METS-IR) index, while depression was evaluated using the Patient Health Questionnaire (PHQ)-9. Logistic regression analyses, subgroup analyses, and dose-response curves were conducted to assess the association between the METS-IR index and depression.

RESULTS

A total of 13,157 adults aged over 20 years were included in this study. After adjusting for potential confounders, it was observed that each unit increase in the METS-IR index was associated with a 1.1 percentage point increase in the prevalence of depression (OR = 1.011; 95 % CI: 1.008, 1.014). Patients in the 4th quartile of the METS-IR index had a higher likelihood of depression compared to those in the 1st quartile (OR = 1.386, 95 % CI: 1.239, 1.549). Stratified analyses demonstrated consistent results in all subgroups, except for men, patients under 40 years of age, and those with a history of cancer. Dose-response curves indicated a nonlinear relationship between the METS-IR index and the risk of depression, with an inflection point value of 32.443 according to threshold effect analysis.

CONCLUSIONS

Our findings suggest that higher METS-IR scores are associated with an increased likelihood of experiencing depressive symptoms among U.S. adults.

Ketogenic Diet Intervention on Metabolic and Psychiatric Health in Bipolar and Schizophrenia: A Pilot Trial

The ketogenic diet (KD, also known as metabolic therapy) has been successful in the treatment of obesity, type 2 diabetes, and epilepsy. More recently, this treatment has shown promise in the treatment of psychiatric illness. We conducted a 4-month pilot study to investigate the effects of a KD on individuals with schizophrenia or bipolar disorder with existing metabolic abnormalities. Twenty-three participants were enrolled in a single-arm trial. Results showcased improvements in metabolic health, with no participants meeting metabolic syndrome criteria by study conclusion. Adherent individuals experienced significant reduction in weight (12 %), BMI (12 %), waist circumference (13 %), and visceral adipose tissue (36 %). Observed biomarker enhancements in this population include a 27 % decrease in HOMA-IR, and a 25 % drop in triglyceride levels. In psychiatric measurements, participants with schizophrenia showed a 32 % reduction in Brief Psychiatric Rating Scale scores. Overall Clinical Global Impression (CGI) severity improved by an average of 31 %, and the proportion of participants that started with elevated symptomatology improved at least 1-point on CGI (79 %). Psychiatric outcomes across the cohort encompassed increased life satisfaction (17 %) and enhanced sleep quality (19 %). This pilot trial underscores the potential advantages of adjunctive ketogenic dietary treatment in individuals grappling with serious mental illness.

Higher serum chromium level may be associated with the presentation of depression in patients with metabolic dysfunction-associated fatty liver disease: evidence from NHANES survey

Background

Depressive symptoms are frequently observed in patients with Metabolic Dysfunction-Associated Fatty Liver Disease (MAFLD), a prevalent metabolic disorder that affects many individuals. It is not yet clear whether there is an association between serum chromium levels and depression.

Objective

The purpose of this research was to explore the association between serum chromium level and the manifestation of depression among patients with MAFLD.

Methods

The selection of 1837 patients diagnosed with MAFLD was based on data obtained from the 2017-2018 National Health and Nutrition Examination Survey (NHANES) database in this research. The Patient Health Questionnaire-9 (PHQ-9) was employed to evaluate the severity of depression. The researchers utilized logistic regression models that were weighted for multiple variables to investigate the association between depression and serum chromium levels.

Results

In our study, we found that 8.98% of US adults with MAFLD were suffering from depression at the time of evaluation. In the logistic regression model, serum chromium levels showed an inverse association with depression (OR=0.82, 95%CI: 0.69-0.96; p=0.016), this relationship remained after adjusting for fully confounding factors (OR=0.83, 95%CI: 0.71-0.97; p=0.021), subgroup analyses showed that the association between serum chromium levels and depression existed in relatively high-prevalence of depression groups.

Conclusion

Patients diagnosed with MAFLD have a greater likelihood of experiencing depression, whereas individuals with higher levels of serum chromium are less likely to suffer from depression, and this association persists even after adjusting for other factors. These findings indicate supplementing chromium may be a viable treatment for their depressive symptoms.

Efficacy and Safety of Antidiabetic Agents for Major Depressive Disorder and Bipolar Depression: A Meta-Analysis of Randomized, Double-Blind, Placebo-Controlled Trials

BACKGROUND

This meta-analysis aimed to determine the efficacy and safety of antidiabetic agents in the treatment of major depressive disorder and bipolar depression.

METHODS

Randomized controlled trials (RCTs) of antidiabetic agents in major depressive disorder or bipolar depression were searched in three electronic databases and three clinical trial registry websites from their inception up to October 2023. The differences in changes in the depression rating scale scores from baseline to endpoint or pre-defined sessions, response rate, remission rate, rate of side effects and dropout rate between antidiabetic agents and placebo were meta-analyzed.

RESULTS

Six RCTs involving 399 participants were included in the final meta-analysis, which did not find that antidiabetics outperformed the placebo in reducing depressive symptoms. The standardized mean difference (SMD) in the depression scores from baseline to endpoint was 0.25 (95% CI -0.1, 0.61). However, a subgroup analysis found a significant difference between antidiabetics and placebos in reducing depressive symptoms in Middle Eastern populations, with an SMD of 0.89 (95% CI 0.44, 1.34).

CONCLUSIONS

The current meta-analysis does not support the efficacy of antidiabetics being superior to the placebo in the treatment of unipolar and bipolar depression. However, a subgroup analysis indicates that patients from the Middle East may benefit from adding an antidiabetic medication to their ongoing medication(s) for their depression. Larger studies with good-quality study designs are warranted.

Consolidating evidence on the role of insulin resistance in major depressive disorder

PURPOSE OF REVIEW

The circular interactions between type 2 diabetes (TMD2) and major depressive disorder (MDD) are well documented but the understanding of their mechanisms has only recently gained more clarity. Latest research indicates, that the association between TMD2 and MDD is largely mediated by insulin resistance (IR).

RECENT FINDINGS

A metabolic subtype of MDD can be distinguished from other MDD subpopulations, that is characterized by predominantly atypical clinical presentation, IR and different responsiveness to antidepressant interventions. IR is a predictor of nonresponse to some antidepressants. The IR seems to be a state-marker of clinical or subclinical depression and the relationship between IR and MDD varies between sexes and ethnicities. Insulin has a direct impact on the monoaminergic systems known to underlie MDD symptoms: serotoninergic and dopaminergic, which are dysregulated in IR subjects. Several trials assessed the efficacy of insulin-sensitizing drugs in MDD with mixed results for metformin and more consistent evidence for pioglitazone and lifestyle intervention/physical activity.

SUMMARY

Recently published data suggest a significant role of IR in the clinical presentation, pathophysiology and treatment response in MDD. Further research of IR in MDD and integration of existing data into clinical practice are needed.

Impaired eating behaviors but intact metabolic hormone levels in individuals with major depressive disorder and generalized anxiety disorder

BACKGROUND

Major depressive disorder (MDD) and generalized anxiety disorder (GAD) contribute significantly to global health burdens. Identifying disease markers for these comorbid disorders can increase understanding of pathogenesis and improve screening and intervention strategies. This study examined the association of physical health factors with MDD and MDD + GAD, across sexes.

METHODS

Two samples of participants from the Tulsa-1000 study (exploratory cohort: N = 136; confirmatory cohort: N = 185) completed body composition measurements, eating behavior (Three Factor Eating Questionnaire [TFEQ], Eating Disorder Diagnostic Scale [EDDS]), exercise questionnaires, and a blood draw. Metabolic hormone concentrations (leptin, insulin, and adiponectin) were analyzed from blood samples. Within each cohort, a two-way analysis of variance compared three groups (MDD, MDD + GAD, and healthy controls [HC]), sex, and their interaction on dependent variables. Hedges g was calculated to reflect effect size magnitude.

RESULTS

Medium-to-large group main effects across cohorts indicated that compared to HC: (1) MDD (g = 1.71/0.57) and MDD + GAD (g = 0.93/0.69) reported higher TFEQ Disinhibition scores; (2) MDD endorsed higher TFEQ Hunger scores (g = 0.66/0.48); and (3) MDD (g = 1.60/1.30) and MDD + GAD (g = 0.92/1.72) reported greater EDDS scores. Large sex main effects across cohorts indicated that females exhibited higher levels than males for percent body fat (g = 1.07/1.17), leptin (g = 1.27/1.12), and adiponectin (g=0.82/0.88).

LIMITATIONS

The power to detect group*sex interactions was limited due to a greater number of females (than males) in the study, and over half of clinical participants were taking medications.

CONCLUSIONS

Individuals with MDD and MDD + GAD demonstrate difficulties in regulating eating behaviors, potentially contributing to functional impairment and increased disease burden.

The association between insulin resistance and depressive symptoms - A national representative cross-sectional study

OBJECTIVE

Increasing evidence suggests a positive association between insulin resistance (IR) and depression. However, whether sex-or body mass index-specific differences exist remains controversial, and only few studies have analyzed specific symptom domains. Thus, the present study aimed to analyze the association between IR and depressive symptom domains and to clarify the effects of sex and body mass index.

METHODS

The study sample comprised 4007 participants, aged 19-79, from the Korea National Health and Nutrition Examination Study 2020. Participants completed health interviews and examinations, providing data on circulating insulin and glucose levels, the Patient Health Questionnaire-9 (PHQ-9), and related covariates. IR was calculated using the homeostasis model assessment of insulin resistance. Associations between IR and PHQ-9 were analyzed using negative binomial regression with adjustments for the complex survey design.

RESULTS

The association between log-transformed IR and PHQ-9 total scores was statistically significant (incidence rate ratio [IRR] = 1.17, 95% confidence interval [CI] = 1.07-1.29, p = 0.001). Only body mass index specific differences were statistically significant, as the association was only significant in those without obesity (IRR = 1.21, 95% CI = 1.06-1.38, p = 0.005). IR was associated with cognitive/affective (IRR = 1.23, 95% CI = 1.08-1.41, p = 0.002) and somatic (IRR = 1.14, 95% CI = 1.04-1.25, p = 0.005) depressive symptom domains. Sensitivity analyses revealed similar results.

CONCLUSIONS

IR was positively associated with cognitive/affective and somatic depressive symptoms in non-obese individuals.

Associations between triglyceride glucose index and depression in middle-aged and elderly adults: A cross-sectional study

The pathogenesis of depression is unclear, and it responds poorly to treatment. It is thus urgent to identify the pathogenesis of depression and possible therapeutic targets. There may be interactions between insulin resistance (IR) and depression. The purpose of this study was to explore the relationship between depression, triglyceride glucose (TyG) index. The study participants were 198 middle-aged and elderly patients who were admitted to the Hebei General Hospital between January 1, 2021, and August 31, 2022, together with 189 healthy adults as controls. Depression was diagnosed according to ICD-10 diagnostic criteria for depression. IR was assessed by the TyG index. Compared with the control group, patients suffering from depression had higher TyG index (P = .00); There were significant differences in the sex ratio (P = .00), family history (P = .00), body mass index (P = .008), total cholesterol (P = .00), fasting blood glucose (P = .004), high-density lipoprotein (P = .00), and low-density lipoprotein (P = .001) levels between the 2 groups. After excluding other confounding factors, the TyG index was found to be independently associated with depression, with an OR of 2.75. These data support an association of depression with the TyG index. IR thus appears to be a risk factor for depression.

Toward a Precision Treatment Approach for Metabolic Depression: Integrating Epidemiology, Neuroscience, and Psychiatry

Background

Individuals with comorbid major depressive disorder and type 2 diabetes represent an important subgroup of patients for whom conventional treatment may be insufficient. A precision treatment approach that addresses insulin resistance with an outcome of a positive response to antidepressants may prove beneficial.

Methods

This study utilized an emulated target trial on a large dataset from the Optum Clinformatics Data Mart Database. We evaluated the effect of adjuvant pioglitazone, an insulin-sensitizing drug, on antidepressant response among 4696 people with type 2 diabetes, comparing it with DPP4 (dipeptidyl peptidase-4) inhibitors (non-insulin-sensitizing). An additional analysis involving 6518 participants was conducted to assess the efficacy of pioglitazone versus sulfonylureas.

Results

The instrumental variable analysis indicated that the initiation of an antidepressant with pioglitazone was superior to DPP4 inhibitors in terms of antidepressant response, with fewer treatment shifts and/or additions of new antidepressant or antipsychotic over a 1-year period. This result was consistent when pioglitazone was compared with sulfonylureas in a supplemental analysis.

Conclusions

Our findings suggest that pioglitazone may be more effective than DPP4 inhibitors or sulfonylureas in enhancing antidepressant response among people with comorbid major depressive disorder and type 2 diabetes. This provides a strong case for the use of pioglitazone in patients with these conditions, emphasizing the potential of precision medicine strategies. The results should be interpreted with caution due to inherent limitations associated with observational data.

Brain insulin signaling as a potential mediator of early life adversity effects on physical and mental health

In numerous brain structures, insulin signaling modulates the homeostatic processes, sensitivity to reward pathways, executive function, memory, and cognition. Through human studies and animal models, mounting evidence implicates central insulin signaling in the metabolic, physiological, and psychological consequences of early life adversity. In this review, we describe the consequences of early life adversity in the brain where insulin signaling is a key factor and how insulin may moderate the effects of adversity on psychiatric and cardio-metabolic health outcomes. Further understanding of how early life adversity and insulin signaling impact specific brain regions and mental and physical health outcomes will assist in prevention, diagnosis, and potential intervention following early life adversity.

Impact of insulin and insulin resistance on brain dopamine signalling and reward processing- an underexplored mechanism in the pathophysiology of depression?

Type 2 diabetes and major depressive disorder (MDD) are the leading causes of disability worldwide and have a high comorbidity rate with fatal outcomes. Despite the long-established association between these conditions, the underlying molecular mechanisms remain unknown. Since the discovery of insulin receptors in the brain and the brain's reward system, evidence has accumulated indicating that insulin modulates dopaminergic (DA) signalling and reward behaviour. Here, we review the evidence from rodent and human studies, that insulin resistance directly alters central DA pathways, which may result in motivational deficits and depressive symptoms. Specifically, we first elaborate on the differential effects of insulin on DA signalling in the ventral tegmental area (VTA) - the primary DA source region in the midbrain - and the striatum as well as its effects on behaviour. We then focus on the alterations induced by insulin deficiency and resistance. Finally, we review the impact of insulin resistance in DA pathways in promoting depressive symptoms and anhedonia on a molecular and epidemiological level and discuss its relevance for stratified treatment strategies.

Dynamic relationships between depressive symptoms and insulin resistance over 20 years of adulthood

BACKGROUND

Bidirectional longitudinal relationships between depression and diabetes have been observed, but the dominant direction of their temporal relationships remains controversial.

METHODS

The random-intercept cross-lagged panel model decomposes observed variables into a latent intercept representing the traits, and occasion-specific latent 'state' variables. This permits correlations to be assessed between the traits, while longitudinal 'cross-lagged' associations and cross-sectional correlations can be assessed between occasion-specific latent variables. We examined dynamic relationships between depressive symptoms and insulin resistance across five visits over 20 years of adulthood in the population-based Coronary Artery Risk Development in Young Adults (CARDIA) study. Possible differences based on population group (Black v. White participants), sex and years of education were tested. Depressive symptoms and insulin resistance were quantified using the Center for Epidemiologic Studies Depression (CES-D) scale and the homeostatic model assessment for insulin resistance (HOMA-IR), respectively.

RESULTS

Among 4044 participants (baseline mean age 34.9 ± 3.7 years, 53% women, 51% Black participants), HOMA-IR and CES-D traits were weakly correlated (r = 0.081, p = 0.002). Some occasion-specific correlations, but no cross-lagged associations were observed overall. Longitudinal dynamics of these relationships differed by population groups such that HOMA-IR at age 50 was associated with CES-D score at age 55 (β = 0.076, p = 0.038) in White participants only. Longitudinal dynamics were consistent between sexes and based on education.

CONCLUSIONS

The relationship between depressive symptoms and insulin resistance was best characterized by weak correlations between occasion-specific states and enduring traits, with weak evidence that insulin resistance might be temporally associated with subsequent depressive symptoms among White participants later in adulthood.

Association between impaired glucose metabolism and long-term prognosis at the time of diagnosis of depression: Impaired glucose metabolism as a promising biomarker proposed through a machine-learning approach

BACKGROUND

Predicting the course of depression is necessary for personalized treatment. Impaired glucose metabolism (IGM) was introduced as a promising depression biomarker, but no consensus was made. This study aimed to predict IGM at the time of depression diagnosis and examine the relationship between long-term prognosis and predicted results.

METHODS

Clinical data were extracted from four electronic health records in South Korea. The study population included patients with depression, and the outcome was IGM within 1 year. One database was used to develop the model using three algorithms. External validation was performed using the best algorithm across the three databases. The area under the curve (AUC) was calculated to determine the model's performance. Kaplan-Meier and Cox survival analyses of the risk of hospitalization for depression as the long-term outcome were performed. A meta-analysis of the long-term outcome was performed across the four databases.

RESULTS

A prediction model was developed using the data of 3,668 people, with an AUC of 0.781 with least absolute shrinkage and selection operator (LASSO) logistic regression. In the external validation, the AUCs were 0.643, 0.610, and 0.515. Through the predicted results, survival analysis and meta-analysis were performed; the hazard ratios of risk of hospitalization for depression in patients predicted to have IGM was 1.20 (95% confidence interval [CI] 1.02-1.41, p = 0.027) at a 3-year follow-up.

CONCLUSIONS

We developed prediction models for IGM occurrence within a year. The predicted results were related to the long-term prognosis of depression, presenting as a promising IGM biomarker related to the prognosis of depression.

Canonical insulin signaling is not significantly impaired in early stages of depression

Patients with major depression (MD) are at high-risk for insulin resistance (IR), type-2 diabetes, metabolic syndrome, cardiovascular morbidity and mortality. However, our recent study published in this journal [Eur Arch Psychiatry Clin Neurosci. 2019 Jun;269(4):373-377], found no evidence of IR in acutely-ill drug-naive first-episode MD (FEMD) using the homeostatic model assessment of insulin resistance (HOMA-IR). We concluded, that MD may be related to impaired glucose/insulin homeostasis in the long-term but not in early disease stages. Now, we performed a complementary analysis of the canonical insulin signalling pathway containing the set of control and FEMD samples from the study mentioned above. The first node (pS312-IRS-1, pY-IRS-1) and downstream pathway which affects glucose and lipid homeostasis (phosphorylated proteins: pS473-AKT, pS9-GSK3β, pS2448-mTOR, pT389-p70S6K; total proteins AKT, GSK3β, mTOR, p70S6K) were analyzed by electrochemiluminescence (ECL) in neuronal extracellular vesicles (nEVs) enriched for L1 neural cell adhesion molecule (L1CAM) expression. No significant diagnosis-related differences were observed for the pS312-IRS-1 / pYIRS-1 ratio (P = 0.093), but the mean ratio was reduced by ~ 70% in FEMD versus controls. Moreover, omnibus analysis of downstream phosphorylated / total signaling protein ratios and respective post-hoc analyses revealed no significant changes in FEMD patients versus controls (P = 0.734). HAMD-21 scores were not correlated with pS312-IRS-1 / pY-IRS-1 or downstream phosphorylated/total signaling protein ratios. In summary, we did not find evidence for altered neuronal insulin signaling in early disease stages of MD. This is in contrast to schizophrenia, where we and other researchers have seen evidence of IR in first-episode patients.

The association between dietary inflammation index and depression

Objective

We aimed to evaluate whether depression is associated with increased risk of dietary inflammatory index (DII) or energy-adjusted DII (E-DII) and whether the association is partly explained by insulin resistance (IR).

Methods

Base on the National Health and Nutrition Examination Survey (NHANES) 2005-2018. Univariate analyses of continuous and categorical variables were performed using t-test, ANOVA, and χ ² test, respectively. Logistic regression was used to analyze the relationship between DII or E-DII and depression in three different models. Mediation analysis was used to assess the potential mediation effects of homeostatic model assessment-IR (HOMA-IR).

Results

A total of 70,190 participants were included, and the DII score was higher in the depressed group. DII score was related to all participant characteristics except age (p < 0.05). After being included in covariates (Model 3), participants in the highest quartile of DII score have increased odds of depression (OR: 1.82, 95% CI: 1.28-2.58) compared with those in the first quartile of DII score. And, a significant dose-response relationship was found (p-trend <0.05). No interaction between DII and HOMA-IR was observed in terms of the risk of depression, and HOMA-IR did not find to play a mediating role in the association between DII and depression. Similar results were obtained for the association between E-DII and depression.

Conclusion

Our results suggest that a higher pro-inflammatory diet increases the risk of depression in U.S. adults, while there was no evidence of a multiplicative effect of DII or E-DII and HOMA-IR on disease risk, nor of a mediating effect of HOMA-IR.

Long-term dietary acid load is associated with depression in multiple sclerosis, but less evidence was found with fatigue and anxiety

BACKGROUND

Diet-dependent acid-base load has been associated with worsening in mental health, but to date no study has examined this in people with multiple sclerosis (PwMS). We examined the association between potential renal acid load (PRAL) and net endogenous acid production (NEAP) scores and depression, anxiety, and fatigue in PwMS.

METHODS

Participants with a first clinical diagnosis of CNS demyelination were followed prospectively as part of the AusLong Study (aged 18-59 years at cohort entry). At baseline, 5- and 10-year reviews, PRAL and NEAP scores were calculated using dietary intake in the preceding 12 months calculated from a food frequency questionnaire. At 5- and 10-year reviews, the Hospital Anxiety and Depression Scale was used to assess depression and anxiety, and the Fatigue Severity Scale assessed fatigue.

RESULTS

Higher PRAL and NEAP scores were associated with increased subsequent absolute value and change in HADS depression scores over five years' follow-up (e.g., highest vs lowest PRAL quartile, 5-year change in HADS-D score: β=+3.01, 95%CI= 1.54, 4.48, p<0.001). The level of depression at the 10-year review was determined by both the baseline dietary acid scores and baseline-5-year changes in dietary acid scores (e.g., PRAL change from baseline to 5-year review, 10-year review HADS-D score: β=+0.09, 95%CI= 0.03, 0.15, p<0.001, NEAP change from baseline to 5-year review, 10-year review HADS-D score: β=+0.07, 95%CI= 0.01, 0.14, p=0.03). Some associations were observed with anxiety and fatigue but were much weaker and less consistent.

CONCLUSION

Our findings indicate that a higher dietary acid load potentially has a long-term influence on the level of depression in PwMS. The evidence is less convincing for anxiety and fatigue.

The Impact of Type 2 Diabetes in Parkinson's Disease

BACKGROUND

Type 2 diabetes (T2DM) is an established risk factor for developing Parkinson's disease (PD), but its effect on disease progression is not well understood.

OBJECTIVE

The aim of this study was to investigate the influence of T2DM on aspects of disease progression in PD.

METHODS

We analyzed data from the Tracking Parkinson's study to examine the effects of comorbid T2DM on PD progression and quality of life by comparing symptom severity scores assessing a range of motor and nonmotor symptoms.

RESULTS

We identified 167 (8.7%) patients with PD and T2DM (PD + T2DM) and 1763 (91.3%) patients with PD without T2DM (PD). After controlling for confounders, patients with T2DM had more severe motor symptoms, as assessed by Movement Disorder Society Unified Parkinson's Disease Rating Scale, Part III (25.8 [0.9] vs. 22.5 [0.3] P = 0.002), and nonmotor symptoms, as assessed by Non-Motor Symptoms Scale total (38.4 [2.5] vs. 31.8 [0.7] P < 0.001), and were significantly more likely to report loss of independence (odds ratio, 2.08; 95% confidence interval [CI]: 1.34-3.25; P = 0.001) and depression (odds ratio, 1.62; CI: 1.10-2.39; P = 0.015). Furthermore, over time, patients with T2DM had significantly faster motor symptom progression (P = 0.012), developed worse mood symptoms (P = 0.041), and were more likely to develop substantial gait impairment (hazard ratio, 1.55; CI: 1.07-2.23; P = 0.020) and mild cognitive impairment (hazard ratio, 1.7; CI: 1.24-2.51; P = 0.002) compared with the PD group.

CONCLUSIONS

In the largest study to date, T2DM is associated with faster disease progression in Parkinson's, highlighting an interaction between these two diseases. Because it is a potentially modifiable metabolic state, with multiple peripheral and central targets for intervention, it may represent a target for alleviating parkinsonian symptoms and slowing progression to disability and dementia. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Insulin resistance in depression: A large meta-analysis of metabolic parameters and variation

Increased insulin resistance is recognized in psychiatric disorders, such as schizophrenia and bipolar disorder, but its occurrence in depression is less clear. Our aims were to verify if insulin resistance is altered in depression, to test the metabolic subgroup hypothesis of depression and if there are changes with antidepressants. Inclusion criteria were studies including adult subjects with depression and either a control group or follow-up after treatment with antidepressants, and assessing fasting insulin or glucose levels or the Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) index. Seventy studies with 240,704 participants were included. Both insulin levels and the HOMA-IR index were increased in acute depression. Neither insulin nor the HOMA-IR index were altered during remission. Insulin was increased in atypical, but not typical depression. There was higher variation in insulin in individuals with depression than in controls. Insulin resistance did not change with antidepressant treatment. Insulin resistance is increased in depression during acute episodes. Heterogeneity was high in most of the analyses. Laboratory assessment of insulin resistance might have clinical utility in people with depression for diagnosis of the metabolic subtype and treatment selection, following precision psychiatry standards.

The Role of Ketogenic Metabolic Therapy on the Brain in Serious Mental Illness: A Review

In search of interventions targeting brain dysfunction and underlying cognitive impairment in schizophrenia, we look at the brain and beyond to the potential role of dysfunctional systemic metabolism on neural network instability and insulin resistance in serious mental illness. We note that disrupted insulin and cerebral glucose metabolism are seen even in medication-naïve first-episode schizophrenia, suggesting that people with schizophrenia are at risk for Type 2 diabetes and cardiovascular disease, resulting in a shortened life span. Although glucose is the brain's default fuel, ketones are a more efficient fuel for the brain. We highlight evidence that a ketogenic diet can improve both the metabolic and neural stability profiles. Specifically, a ketogenic diet improves mitochondrial metabolism, neurotransmitter function, oxidative stress/inflammation, while also increasing neural network stability and cognitive function. To reverse the neurodegenerative process, increasing the brain's access to ketone bodies may be needed. We describe evidence that metabolic, neuroprotective, and neurochemical benefits of a ketogenic diet potentially provide symptomatic relief to people with schizophrenia while also improving their cardiovascular or metabolic health. We review evidence for KD side effects and note that although high in fat it improves various cardiovascular and metabolic risk markers in overweight/obese individuals. We conclude by calling for controlled clinical trials to confirm or refute the findings from anecdotal and case reports to address the potential beneficial effects of the ketogenic diet in people with serious mental illness.

Early adversity and insulin: neuroendocrine programming beyond glucocorticoids

Exposure to direct or contextual adversities during early life programs the functioning of the brain and other biological systems, contributing to the development of physical as well as mental health issues in the long term. While the role of glucocorticoids in mediating the outcomes of early adversity has been explored for many years, less attention has been given to insulin. Beyond its metabolic effects in the periphery, central insulin action affects synaptic plasticity, brain neurotransmission, and executive functions. Knowledge about the interactions between the peripheral metabolism and brain function from a developmental perspective can contribute to prevention and diagnosis programs, as well as early interventions for vulnerable populations.

The Interplay between Housing Environmental Attributes and Design Exposures and Psychoneuroimmunology Profile-An Exploratory Review and Analysis Paper in the Cancer Survivors' Mental Health Morbidity Context

Adult cancer survivors have an increased prevalence of mental health comorbidities and other adverse late-effects interdependent with mental illness outcomes compared with the general population. Coronavirus Disease 2019 (COVID-19) heralds an era of renewed call for actions to identify sustainable modalities to facilitate the constructs of cancer survivorship care and health care delivery through physiological supportive domestic spaces. Building on the concept of therapeutic architecture, psychoneuroimmunology (PNI) indicators-with the central role in low-grade systemic inflammation-are associated with major psychiatric disorders and late effects of post-cancer treatment. Immune disturbances might mediate the effects of environmental determinants on behaviour and mental disorders. Whilst attention is paid to the non-objective measurements for examining the home environmental domains and mental health outcomes, little is gathered about the multidimensional effects on physiological responses. This exploratory review presents a first analysis of how addressing the PNI outcomes serves as a catalyst for therapeutic housing research. We argue the crucial component of housing in supporting the sustainable primary care and public health-based cancer survivorship care model, particularly in the psychopathology context. Ultimately, we illustrate a series of interventions aiming at how housing environmental attributes can trigger PNI profile changes and discuss the potential implications in the non-pharmacological treatment of cancer survivors and patients with mental morbidities.

Clinical laboratory tests and five-year incidence of major depressive disorder: a prospective cohort study of 433,890 participants from the UK Biobank

Prevention of major depressive disorder (MDD) is a public health priority. Identifying biomarkers of underlying biological processes that contribute to MDD onset may help address this public health need. This prospective cohort study encompassed 383,131 white British participants from the UK Biobank with no prior history of MDD, with replication in 50,759 participants of other ancestries. Leveraging linked inpatient and primary care records, we computed adjusted odds ratios for 5-year MDD incidence among individuals with values below or above the 95% confidence interval (<2.5th or >97.5th percentile) on each of 57 laboratory measures. Sensitivity analyses were performed across multiple percentile thresholds and in comparison to established reference ranges. We found that indicators of liver dysfunction were associated with increased 5-year MDD incidence (even after correction for alcohol use and body mass index): elevated alanine aminotransferase (AOR = 1.35, 95% confidence interval [1.16, 1.58]), aspartate aminotransferase (AOR = 1.39 [1.19, 1.62]), and gamma glutamyltransferase (AOR = 1.52 [1.31, 1.76]) as well as low albumin (AOR = 1.28 [1.09, 1.50]). Similar observations were made with respect to endocrine dysregulation, specifically low insulin-like growth factor 1 (AOR = 1.34 [1.16, 1.55]), low testosterone among males (AOR = 1.60 [1.27, 2.00]), and elevated glycated hemoglobin (HbA1C; AOR = 1.23 [1.05, 1.43]). Markers of renal impairment (i.e. elevated cystatin C, phosphate, and urea) and indicators of anemia and macrocytosis (i.e. red blood cell enlargement) were also associated with MDD incidence. While some immune markers, like elevated white blood cell and neutrophil count, were associated with MDD (AOR = 1.23 [1.07, 1.42]), others, like elevated C-reactive protein, were not (AOR = 1.04 [0.89, 1.22]). The 30 significant associations validated as a group in the multi-ancestry replication cohort (Wilcoxon p = 0.0005), with a median AOR of 1.235. Importantly, all 30 significant associations with extreme laboratory test results were directionally consistent with an increased MDD risk. In sum, markers of liver and kidney dysfunction, growth hormone and testosterone deficiency, innate immunity, anemia, macrocytosis, and insulin resistance were associated with MDD incidence in a large community-based cohort. Our results support a contributory role of diverse biological processes to MDD onset.

Adiposity in Depression or Depression in Adiposity? The Role of Immune-Inflammatory-Microbial Overlap

Some of the most common and debilitating conditions are metabolic disorders (metabolic syndrome and non-alcoholic fatty liver disease) and depression. These conditions are also exacerbated by the fact that they often co-occur. Although the exact mechanisms underlying such relationships are poorly known, antipsychotic medication and antidepressant use, diet and physical activity, and lifestyle factors are believed to play a role; however, their high co-occurrence rate suggests a possible pathophysiological overlap. This paper reviews several possible bases for this overlap, including hypothalamic-pituitary-adrenal axis dysregulation, immune alterations with chronic inflammation, and oxidative stress. While it is entirely possible that changes in the microbiota may play a role in each of them, interventions based on the implementation of dietary and other lifestyle changes, supplementation with prebiotics or probiotics and faecal microbiota transplantation have failed to achieve conclusive results. A better characterization of the above associations may allow a more targeted approach to the treatment of both depressive and metabolic disorders. The paper also presents several practical applications for future studies.