Targeting Metabolic Dysfunction for the Treatment of Mood Disorders: Review of the Evidence

Better understanding of c-reactive protein and leukocytes in psychiatric inpatients with affective disorders: A biopsychosocial approach

BACKGROUND

Affective disorders (AD) have been linked to inflammatory processes, although the underlying mechanisms of this relationship are still not fully elucidated. It is hypothesized that demographic, somatic, lifestyle, and personality variables predict inflammatory parameters in AD.

AIM

To identify biopsychosocial factors contributing to inflammation in AD measured with two parameters, C-reactive protein (CRP) and leukocytes.

METHODS

This observational study investigated 186 hospital inpatients diagnosed with AD using demographic parameters, serum inflammatory markers, somatic variables, psychological questionnaires, and lifestyle parameters. Hierarchical regression analyses were used to predict inflammatory markers from demographic, somatic, lifestyle, and personality variables.

RESULTS

Analyses showed that 33.8% of the variance of CRP was explained by body mass index and other somatic medication (e.g. anti-diabetics), age and education, and age of affective disorder diagnosis. For leukocytes, 20.1% of the variance was explained by smoking, diet, metabolic syndrome (MetS), and anti-inflammatory medication (e.g. non-steroidal anti-inflammatory drugs). Other psychiatric or behavioural variables did not reach significance.

CONCLUSION

Metabolic components seem important, with mounting evidence for a metabolic affective disorder subtype. Lifestyle modifications and psychoeducation should be employed to prevent or treat MetS in AD.

Assessing the Effects of Metabolic Disruption, Body Mass Index and Inflammation on Depressive Symptoms in Post-COVID-19 Condition: A Randomized Controlled Trial on Vortioxetine

INTRODUCTION

To date, there are no therapeutics that have gained regulatory approval by the United States Food and Drug Administration (FDA) for the treatment of post-COVID-19 condition (PCC), a debilitating condition characterized by cognitive impairment and mood symptoms. Additionally, persistent inflammation, metabolic dysfunction, and risks associated with an elevated body mass index (BMI) have been observed. Herein, we aimed to assess the efficacy of vortioxetine in improving depressive symptoms among individuals with PCC,  as modulated by inflammation, metabolic dysfunction, and BMI.

METHODS

In this post-hoc analysis, we present preliminary data obtained from an 8-week randomized, double-blind, placebo-controlled trial. Participants included  adults aged 18 years and older residing in Canada who were experiencing symptoms of World Health Organization (WHO)-defined PCC. Recruitment began November 2021 and ended January 2023. Of the 200 participants enrolled, 147 were randomized (1:1) to receive vortioxetine (5-20 mg, n = 73) or placebo (n = 74) for daily treatment under double-blind conditions. The primary outcome measure was the change from baseline to endpoint in the 16-Item Quick Inventory of Depressive Symptomatology Self-Report Questionnaire (QIDS-SR-16).

RESULTS

Our findings revealed significant effects for time (χ2 = 9.601, p = 0.002), treatment (χ2 = 9.135, p = 0.003), and the treatment × time × CRP × TG-HDL × BMI interaction (χ2 = 26.092, p < 0.001) on PCC-related depressive symptoms in the adjusted model. Moreover, the between-group analysis showed a significant improvement with vortioxetine at endpoint as compared to placebo (mean difference = - 5.41, SEM = 1.335, p < 0.001).

CONCLUSION

Overall, vortioxetine significantly improved depressive symptoms among participants with PCC in the adjusted model. Notably, individuals with baseline markers of increased inflammation, metabolic disruption, and elevated BMI exhibited a more pronounced antidepressant effect at endpoint.

TRIAL REGISTRATION NUMBER

NCT05047952 (ClinicalTrials.gov).

Severe depressive symptoms in patients with hypertension: Are antihypertensive medications implicated?

OBJECTIVE

This study examined whether antihypertensive medications and other patient characteristics are associated with severe depressive symptoms in patients with hypertension.

METHODS

Patients with a diagnosis of hypertension were recruited from the internal medicine outpatient clinics of a hospital in Amman, Jordan, into this cross-sectional study. Depression severity was assessed using the Patient Health Questionnaire-9 (PHQ-9); anxiety by the General Anxiety Disorder-7; sleep quality by the Insomnia Severity Index; and psychological stress by the Perceived Stress Scale. Multivariable binary logistic regression was used to examine the association between the different classes of antihypertensive medication and depressive symptoms.

RESULTS

Of the 431 participants, 282 (65.4%) were men; 240 (55.7%) reported having type 2 diabetes; 359 (83.3%) had dyslipidemia; 142 (32.9%) were on beta-blockers; 197 (45.2%) were on ACE inhibitors or angiotensin receptor blockers; 203 (47.1%) were on metformin; and 133 (30.9%) were taking sulfonylurea. Severe depressive symptoms, indicated by scoring above the cut-off of 14 on the PHQ-9, were present in 165 (38.3%) patients. Severe depression was associated with younger age (<55 years) (OR = 3.15, 95% CI = 1.83-5.41, P < 0.001), unemployment (OR = 2.15, 95% CI = 1.15-4.00, P = 0.01), diabetes (OR = 1.81, 95% CI = 1.09-3.02, P = 0.02), severe anxiety (OR = 6.40, 95% CI = 3.64-11.28, P < 0.001), and severe insomnia (OR = 4.73, 95% CI = 2.85-7.82, P < 0.001).

CONCLUSION

Severe depressive symptoms were not associated with antihypertensive medications or other drugs used by hypertensive patients. Younger age, diabetes, anxiety, and insomnia were the primary correlates of depression.

Microbiota-gut-brain axis mechanisms in the complex network of bipolar disorders: potential clinical implications and translational opportunities

Bipolar disorders (BD) represent a severe leading disabling mental condition worldwide characterized by episodic and often progressive mood fluctuations with manic and depressive stages. The biological mechanisms underlying the pathophysiology of BD remain incompletely understood, but it seems that there is a complex picture of genetic and environmental factors implicated. Nowadays, gut microbiota is in the spotlight of new research related to this kind of psychiatric disorder, as it can be consistently related to several pathophysiological events observed in BD. In the context of the so-called microbiota-gut-brain (MGB) axis, it is shown to have a strong influence on host neuromodulation and endocrine functions (i.e., controlling the synthesis of neurotransmitters like serotonin or mediating the activation of the hypothalamic-pituitary-adrenal axis), as well as in modulation of host immune responses, critically regulating intestinal, systemic and brain inflammation (neuroinflammation). The present review aims to elucidate pathophysiological mechanisms derived from the MGB axis disruption and possible therapeutic approaches mainly focusing on gut microbiota in the complex network of BD. Understanding the mechanisms of gut microbiota and its bidirectional communication with the immune and other systems can shed light on the discovery of new therapies for improving the clinical management of these patients. Besides, the effect of psychiatric drugs on gut microbiota currently used in BD patients, together with new therapeutical approaches targeting this ecosystem (dietary patterns, probiotics, prebiotics, and other novelties) will also be contemplated.

Effect of Adjunctive Simvastatin on Depressive Symptoms Among Adults With Treatment-Resistant Depression: A Randomized Clinical Trial

IMPORTANCE

Immune-metabolic disturbances have been implicated in the pathophysiology of major depressive disorder and may be more prominent in individuals with treatment-resistant depression (TRD). Preliminary trials suggest that lipid-lowering agents, including statins, may be useful adjunctive treatments for major depressive disorder. However, no adequately powered clinical trials have assessed the antidepressant efficacy of these agents in TRD.

OBJECTIVE

To assess the efficacy and tolerability of adjunctive simvastatin compared with placebo for reduction of depressive symptoms in TRD.

DESIGN, SETTING, AND PARTICIPANTS

This 12-week, double-blind, placebo-controlled randomized clinical trial was conducted in 5 centers in Pakistan. The study involved adults (aged 18-75 years) with a Diagnostic and Statistical Manual of Mental Disorders (Fifth Edition) major depressive episode that had failed to respond to at least 2 adequate trials of antidepressants. Participants were enrolled between March 1, 2019, and February 28, 2021; statistical analysis was performed from February 1 to June 15, 2022, using mixed models.

INTERVENTION

Participants were randomized to receive standard care plus 20 mg/d of simvastatin or placebo.

MAIN OUTCOMES AND MEASURES

The primary outcome was the difference between the 2 groups in change in Montgomery-Åsberg Depression Rating Scale total scores at week 12. Secondary outcomes included changes in scores on the 24-item Hamilton Rating Scale for Depression, the Clinical Global Impression scale, and the 7-item Generalized Anxiety Disorder scale and change in body mass index from baseline to week 12. C-reactive protein and plasma lipids were measured at baseline and week 12.

RESULTS

A total of 150 participants were randomized to simvastatin (n = 77; median [IQR] age, 40 [30-45] years; 43 [56%] female) or placebo (n = 73; median [IQR] age, 35 [31-41] years; 40 [55%] female). A significant baseline to end point reduction in Montgomery-Åsberg Depression Rating Scale total score was observed in both groups and did not differ significantly between groups (estimated mean difference for simvastatin vs placebo, -0.61; 95% CI, -3.69 to 2.46; P = .70). Similarly, there were no significant group differences in any of the secondary outcomes or evidence for differences in adverse effects between groups. A planned secondary analysis indicated that changes in plasma C-reactive protein and lipids from baseline to end point did not mediate response to simvastatin.

CONCLUSIONS AND RELEVANCE

In this randomized clinical trial, simvastatin provided no additional therapeutic benefit for depressive symptoms in TRD compared with standard care.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03435744.

Molecular pathways of major depressive disorder converge on the synapse

Major depressive disorder (MDD) is a psychiatric disease of still poorly understood molecular etiology. Extensive studies at different molecular levels point to a high complexity of numerous interrelated pathways as the underpinnings of depression. Major systems under consideration include monoamines, stress, neurotrophins and neurogenesis, excitatory and inhibitory neurotransmission, mitochondrial dysfunction, (epi)genetics, inflammation, the opioid system, myelination, and the gut-brain axis, among others. This review aims at illustrating how these multiple signaling pathways and systems may interact to provide a more comprehensive view of MDD's neurobiology. In particular, considering the pattern of synaptic activity as the closest physical representation of mood, emotion, and conscience we can conceptualize, each pathway or molecular system will be scrutinized for links to synaptic neurotransmission. Models of the neurobiology of MDD will be discussed as well as future actions to improve the understanding of the disease and treatment options.

Are the antidepressant effects of insulin-sensitizing medications related to improvements in metabolic markers?

Insulin-sensitizing medications were originally used in psychiatric practice to treat weight gain and other metabolic side effects that accompany the use of mood stabilizers, antipsychotics, and some antidepressants. However, in recent studies these medications have been shown to cause improvement in depressive symptoms, creating a potential new indication outside of metabolic regulation. However, it is still unclear whether the antidepressant properties of these medications are associated with improvements in metabolic markers. We performed a systematic search of the literature following PRISMA guidelines of studies investigating antidepressant effects of insulin-sensitizing medications. We specifically focused on whether any improvements in depressive symptoms were connected to the improvement of metabolic dysfunction. Majority of the studies included in this review reported significant improvement in depressive symptoms following treatment with insulin-sensitizing medications. Nine out of the fifteen included studies assessed for a correlation between improvement in symptoms and changes in metabolic markers and only two of the nine studies found such association, with effect sizes ranging from R² = 0.26-0.38. The metabolic variables, which correlated with improvements in depressive symptoms included oral glucose tolerance test, fasting plasma glucose and glycosylated hemoglobin following treatment with pioglitazone or metformin. The use of insulin-sensitizing medications has a clear positive impact on depressive symptoms. However, it seems that the symptom improvement may be unrelated to improvement in metabolic markers or weight. It is unclear which additional mechanisms play a role in the observed clinical improvement. Some alternative options include inflammatory, neuroinflammatory changes, improvements in cognitive functioning or brain structure. Future studies of insulin-sensitizing medications should measure metabolic markers and study the links between changes in metabolic markers and changes in depression. Additionally, it is important to use novel outcomes in these studies, such as changes in cognitive functioning and to investigate not only acute, but also prophylactic treatment effects.

Statins in depression: a repurposed medical treatment can provide novel insights in mental health

Depression has a large burden, but the development of new drugs for its treatment has proved difficult. Progresses in neuroscience have highlighted several physiopathological pathways, notably inflammatory and metabolic ones, likely involved in the genesis of depressive symptoms. A novel strategy proposes to repurpose established medical treatments of known safety and to investigate their potential antidepressant activity. Among numerous candidates, growing evidence suggests that statins may have a positive role in the treatment of depressive disorders, although some have raised concerns about possible depressogenic effects of these widely prescribed medications. This narrative review summarises relevant findings from translational studies implicating many interconnected neurobiological and neuropsychological, cardiovascular, endocrine-metabolic, and immunological mechanisms by which statins could influence mood. Also, the most recent clinical investigations on the effects of statins in depression are presented. Overall, the use of statins for the treatment of depressive symptoms cannot be recommended based on the available literature, though this might change as several larger, methodologically robust studies are being conducted. Nevertheless, statins can already be acknowledged as a driver of innovation in mental health, as they provide a novel perspective to the physical health of people with depression and for the development of more precise antidepressant treatments.

Current Perspectives on Pharmacological and Non-Pharmacological Interventions for the Inflammatory Mechanism of Unipolar Depression

Since depression remains a major public health issue there is a constant need for new and more efficient therapeutic strategies based on the mechanisms involved in the aetiology of depression. Thus, the pathogenic link between depression and inflammation is considered to play a potential key role in the development of such therapies. This review summarizes the results of various pharmacological (non-steroidal anti-inflammatory drugs, aspirin, cyclooxygenase inhibitors, cytokine inhibitors, corticosteroids, statins, minocycline, N-acetyl cysteine, omega-3 fatty acids and probiotics) and non-pharmacological interventions (electroconvulsive therapy, physical exercise and psychological therapy) and outlines their efficacy and discusses potential challenges. Both conventional and non-conventional anti-inflammatory drugs showed promising results according to the specific group of patients. The pre-existing pro-inflammatory status was, in most cases, a predictor for clinical efficacy and, in some cases, a correlation between clinical improvement and changes in various biomarkers was found. Some of the non-pharmacological interventions (physical exercise and electroconvulsive therapy) have also showed beneficial effects for depressive patients with elevated inflammatory markers. Treatments with anti-inflammatory action may improve clinical outcomes in depression, at least for some categories of patients, thus opening the way for a future personalised approach to patients with unipolar depression regarding the inflammation-related mechanism.

Metformin for the Improvement of Comorbid Depression Symptoms in Diabetic Patients: A Systematic Review

Diabetes mellitus and depression are chronic debilitating disorders and can occur comorbidly. They are thought to be linked not only through environmental and behavioral factors but through molecular mechanisms as well. Antidepressant medication and psychological therapy, standard treatments for depressive symptoms in Type 2 diabetes mellitus, are linked to high rates of treatment failure and non-adherence; therefore, understanding the molecular mechanisms linking diabetes and depression could lead to discovering new targets and developing novel therapeutics. Metformin is considered a first-line anti-diabetic medication for Type 2 diabetes mellitus, and several studies have discussed its antidepressant effect. Metformin is thought to promote neurogenesis, enhance spatial memory function and protect the brain against oxidative imbalance. This systematic review aims to compile information on metformin's effect on depression symptoms and assess current knowledge on the relationship between depression and diabetes. After reviewing several studies, we concluded that metformin might help treat comorbid depression in diabetic patients, but before it can be recommended as a depression medication, more extensive and better-designed trials are needed. 

Possible Association of Cholesterol as a Biomarker in Suicide Behavior

Suicides and suicidal behavior are major causes of mortality and morbidity in public health and are a global problem. Various authors have proposed changes in lipid metabolism (total cholesterol decrease) as a possible biological marker for suicidal behavior. The objective of this study was to review the studies that have demonstrated a relationship between serum cholesterol levels and suicidal behavior and to describe the possible pathophysiological mechanisms that associate changes in cholesterol concentration and suicidal behavior. Relevant literature related to serum cholesterol levels and suicidal behavior was identified through various database searches. The data from the existing literature present the findings that relate low cholesterol levels and possible pathophysiological mechanisms (neuroinflammation, serotonergic neurotransmission), genes related to cholesterol synthesis, pharmacological treatments that alter lipid metabolism and the possible participation in suicidal behavior. Nevertheless, future research is required to describe how serum cholesterol affects cholesterol metabolism in the CNS to establish and understand the role of cholesterol in suicidal behavior.