Leptin in depressive episodes: is there a difference between unipolar and bipolar depression?

Adipocytokines levels as potential biomarkers for discriminating patients with a diagnosis of depressive disorder from healthy controls

BACKGROUND

Depressive disorder is a complex mental health condition in which the etiopathogenesis involves several factors. Suitable biomarkers for the development of depression have not yet been established. Alterations in cytokines are assumed to be involved in the pathophysiology of depressive disorder. Adipokines (also known as adipocytokines) are important factors that not only regulate the energy balance but also regulate the inflammatory and immune responses. This study investigated the serum levels of adiponectin, leptin, resistin, chemerin, and fetuin A and the possible role of these adipokines in depressive disorder.

METHODS

We recruited a total of 73 patients diagnosed with recurrent depressive disorder (rDD) and 54 age- and sex-matched healthy controls (HCs). Serum adipocytokines were determined using ELISA kits (R&D, USA). The serum levels of the investigated molecules between depressive patients and HCs were compared, and diagnostic values were evaluated using the receiver operating characteristic (ROC) curve method for discriminating depressive patients from HCs. Correlations between the molecules and clinical variables were also evaluated.

RESULTS

Patients with rDD had lower levels of serum adiponectin and chemerin and higher levels of serum leptin, resistin and fetuin A (p < 0.05) vs. controls. Moreover, ROC curve analysis showed that the area under the curve (AUC) values of above set of adipocytkines were >0.7, with a sensitivity and specificity over 80% in discriminating patients with rDD from HCs.

CONCLUSIONS

These results suggest that circulating adipocytokies may hold promise as biomarkers for the diagnosis of rDD.

Efficacy of low carbohydrate and ketogenic diets in treating mood and anxiety disorders: systematic review and implications for clinical practice

BACKGROUND

There is mounting interest in the potential efficacy of low carbohydrate and very low carbohydrate ketogenic diets in various neurological and psychiatric disorders.

AIMS

To conduct a systematic review and narrative synthesis of low carbohydrate and ketogenic diets (LC/KD) in adults with mood and anxiety disorders.

METHOD

MEDLINE, Embase, PsycINFO and Cochrane databases were systematically searched for articles from inception to 6 September 2022. Studies that included adults with any mood or anxiety disorder treated with a low carbohydrate or ketogenic intervention, reporting effects on mood or anxiety symptoms were eligible for inclusion. PROSPERO registration CRD42019116367.

RESULTS

The search yielded 1377 articles, of which 48 were assessed for full-text eligibility. Twelve heterogeneous studies (stated as ketogenic interventions, albeit with incomplete carbohydrate reporting and measurements of ketosis; diet duration: 2 weeks to 3 years; n = 389; age range 19 to 75 years) were included in the final analysis. This included nine case reports, two cohort studies and one observational study. Data quality was variable, with no high-quality evidence identified. Efficacy, adverse effects and discontinuation rates were not systematically reported. There was some evidence for efficacy of ketogenic diets in those with bipolar disorder, schizoaffective disorder and possibly unipolar depression/anxiety. Relapse after discontinuation of the diet was reported in some individuals.

CONCLUSIONS

Although there is no high-quality evidence of LC/KD efficacy in mood or anxiety disorders, several uncontrolled studies suggest possible beneficial effects. Robust studies are now needed to demonstrate efficacy, to identify clinical groups who may benefit and whether a ketogenic diet (beyond low carbohydrate) is required and to characterise adverse effects and the risk of relapse after diet discontinuation.

Appetite-regulating hormones in bipolar disorder: A systematic review and meta-analysis

Impaired hormonal regulation of appetite may contribute to higher cardiovascular risk in bipolar disorder (BD). We performed a systematic review and meta-analysis of studies investigating peripheral blood levels of appetite-regulating hormones in BD and controls. A total of 32 studies were included. Leptin and insulin levels were significantly elevated in patients with BD during euthymia, but not in other mood states. Greater differences in the number of male participants between patients with BD and healthy controls were associated with higher effect size estimates for the levels of insulin. There were significant positive correlations of effect size estimates for the levels of adiponectin with the percentage of individuals with type I BD and duration of BD. Our findings point to the mechanisms underlying high rates of cardiometabolic comorbidities in BD. Moreover, they suggest that investigating hormonal regulation of appetite might help to understand differences in the neurobiology of BD types.

Comparison of Executive Dysfunction, Proinflammatory Cytokines, and Appetite Hormones Between First-Episode and Multiple-Episode Bipolar Disorder

Background

Evidence has demonstrated associations of bipolar disorder (BD) with cognitive impairment, dysregulated proinflammatory cytokines, and appetite hormones.

Aim

To compare executive dysfunction, proinflammatory cytokines, and appetite hormones between patients with first-episode and multiple-episode BDs.

Methods

This cross-sectional study included young adults aged 18 to 39 years who were diagnosed as having type 1 BD in the first or recurrent episode and a group of age-/sex-matched healthy controls. Data regarding patient characteristics, clinical symptoms, cytokines (C-reactive protein [CRP], interleukin-6, and tumor necrosis factor [TNF]-α), appetite hormones (leptin, adiponectin, ghrelin, and insulin), and executive function evaluated using the Wisconsin Card Sorting Test (WCST) were collected.

Results

A total of 112 participants (38 patients in the multiple-episode BD group, 31 patients in the first-episode BD group, and 43 in the control group) were included. Multivariate analysis revealed that patients in the multiple-episode BD group performed significantly worse in the WCST (P < .05) and had higher levels of ghrelin (P = .002), and lower levels of CRP (P = .040) than those in the first-episode BD group. Patients with BD had significantly higher TNF-α and ghrelin levels compared with the healthy controls. No significant associations of CRP, TNF-α, and ghrelin levels with executive function were observed.

Conclusions

Profiles in proinflammatory cytokines and appetite hormones as well as executive function significantly differed between patients with first-episode and multiple-episode BDs and controls, which may suggest their potential roles in the clinical stages and pathophysiology of type 1 BD.

Leptin polymorphism rs3828942: risk for anxiety disorders?

Leptin is an anorexigenic hormone well recognized by its role in mediating energy homeostasis. Recently, leptin has been associated with psychiatric disorders and interestingly, leptin treatment has shown antidepressant and anxiolytic effects. We examined the association of leptin levels and leptin (LEP) gene rs3828942 polymorphism with anxiety disorders considering sex differences. A cross-sectional population-based study, including 1067 young adults, of whom 291 presented anxiety disorders diagnosed by the Mini International Neuropsychiatric Interview (MINI 5.0). The rs3828942 polymorphism was genotyped by real-time PCR and ELISA measured leptin levels. Leptin levels were not associated with anxiety disorders after adjusting for sex and body mass index (BMI) [ß = - 0.009 (- 0.090-0.072); p = 0.832]. The distribution of rs3828942 genotypes was not associated with anxiety disorders. However, in a sex-stratified sample, the A-allele of rs3828942 polymorphism was associated with risk for GAD in women even when adjusting for confounding variables [OR = 1.87 (1.17-2.98); p = 0.008]. In a subsample of 202 individuals with GAD and control matched by sex and BMI, results suggest an interaction between genotypes and GAD diagnosis based on leptin levels only in the male group [F (1, 54) = 6.464; p = 0.0139]. Leptin is suggested to be related with the neurobiology of anxiety disorders in a sex-dependent manner since women carrying the A-allele of LEP rs3828942 present a higher risk for GAD, while leptin levels seem to be lower in men with GAD carrying A-allele. Studies on the relationship between leptin polymorphisms and levels are scarce and, therefore, further research is necessary.

Role of appetite hormone dysregulation in the cognitive function among patients with bipolar disorder and major depressive disorder

OBJECTIVES

The association of appetite hormones with cognitive function in patients with affective disorders remains unknown.

METHODS

All total, 58 adult patients with bipolar I disorder, 36 with bipolar II disorder, 40 with major depressive disorder were enrolled and age and sex-matched with 40 controls. The levels of appetite hormones leptin, ghrelin, insulin and adiponectin were assessed. Wisconsin Card Sorting Test was used to assess executive function.

RESULTS

A general linear model, adjusted for demographic data and clinical symptoms, demonstrated the ghrelin levels were higher in patients with bipolar I or II disorder than in those with major depressive disorder and controls (p < 0.001). We also identified a positive correlation of ghrelin level and executive function among patients with bipolar I (p = 0.033) and II (p = 0.027) disorders, but not among those with major depressive disorder and controls.

CONCLUSIONS

Patients with bipolar I or II disorder were more likely to have high levels of ghrelin than patients with major depressive disorder and controls, which may have a positive correlation on the cognitive function of patients with bipolar I or II disorder.

Using classification and regression tree modeling to investigate appetite hormones and proinflammatory cytokines as biomarkers to differentiate bipolar I depression from major depressive disorder

BACKGROUND

Altered immunity and metabolic profiles have been compared between bipolar depression (BD) and major depressive disorder (MDD). This study aimed at developing a composite predictor of appetite hormones and proinflammatory cytokines to differentiate BD from MDD.

METHODS

This cross-sectional study enrolled patients with BD and those with MDD aged 20 to 59 years and displaying depressive episodes. Clinical characteristics (age, sex, body mass index, and depression severity), cytokines (C-reactive protein, interleukin [IL]-2, IL-6, tumor necrosis factor [TNF]-α, P-selectin, and monocyte chemoattractant protein), and appetite hormones (leptin, adiponectin, ghrelin, and insulin) were assessed as potential predictors using a classification and regression tree (CRT) model for differentiating BD from MDD.

RESULTS

The predicted probability of a composite predictor of ghrelin and TNF-α was significantly greater (for BD: area under curve = 0.877; for MDD: area under curve = 0.914) than that of any one marker (all P > .05) to distinguish BD from MDD. The most powerful predictors for diagnosing BD were high ghrelin and TNF-α levels, whereas those for MDD were low ghrelin and TNF-α levels.

CONCLUSION

A composite predictor of ghrelin and TNF-α driven by CRT could assist in the differential diagnosis of BD from MDD with high specificity. Further clinical studies are warranted to validate our results and to explore underlying mechanisms.

Leptin in bipolar disorder: A systematic review and meta-analysis

Background

Bipolar disorder (BD) is a psychiatric disorder associated with increased rates of obesity and inflammation. Leptin is an adipokine that is mainly produced by the white adipose tissue in response to insulin. It stimulates the immune system, increasing the production of pro-inflammatory cytokines. There is currently uncertainty regarding possible alterations in peripheral leptin levels across the mood states in BD.

Methods

This study comprises a between-group meta-analysis comparing serum and plasma leptin levels in people with BD in mania, depression or euthymia and healthy controls. We conducted a systematic search for all possibly eligible-English and non-English peer-reviewed articles. We calculated the effect size (ES) utilizing Hedges’ adjusted g using random effects.

Results

Eleven studies were included in the meta-analyses, providing data on 1118 participants. Serum and plasma leptin levels were not altered in subjects with BD when compared to healthy controls in mania (g = −0.99, 95% CI −2.43 to 0.43, P = 0.171), in depression (g = 0.17, 95% CI −0.45 to 0.79, P = 0.584), or in euthymia (g = 0.03, 95% CI −0.39 to 0.46, P = 0.882). However, we did observe a stronger association between leptin levels and both age and BMI in patients with BD in euthymia compared to healthy controls, such that the greater the age of the individuals, the greater the difference in leptin levels between BD and controls; and the higher the BMI, the greater the difference in leptin levels between BD and controls.

Conclusions

Our meta-analysis provides evidence that leptin levels are not altered in BD across the mood spectrum compared to healthy controls. The disproportionate increase of leptin levels with increase in BMI in BD speaks in favour of a potential inflammatory role of white adipose tissue in BD and a disproportionate increase of leptin levels with increase in age.

Association of Body Dysmorphic Disorder with Leptin Levels in Patients with Normal Weight Undergoing Liposuction: A Matched Case Study

Liposuction is the most common aesthetic surgical procedure performed globally. Some of the patients with normal weight who seek liposuction may suffer from body dysmorphic disorder (BDD). Leptin, which is mainly produced by adipose tissue, may be associated with this condition. The aim of this study was to determine the prevalence of BDD and leptin levels in patients with normal weight seeking liposuction.

Double-blind, placebo-controlled trial of pioglitazone for bipolar depression

BACKGROUND

Objective of the present study was to conduct an 8-week double-blind, randomized, placebo-controlled trial to test the efficacy of pioglitazone in the treatment of bipolar depression.

METHODS

38 outpatients with bipolar disorder and current major depressive episode were randomized to pioglitazone (15-45 mg/day) or placebo. The use of concomitant mood stabilizers, antipsychotics, and antidepressants was permitted. The primary outcome measure was the 30-item Inventory of Depressive Symptomatology, Clinician Rated (IDS-C30) total score change from baseline to endpoint. Laboratory evaluations, including serum level of inflammatory and metabolic biomarkers, were conducted.

RESULTS

37 subjects were analyzed for efficacy (1 subject had no follow-up data). Mean reduction from baseline to week 8 in IDS-C30 score was-6.59 for pioglitazone and -11.63 for placebo. Mixed effects modeling indicated borderline statistically significant difference between the two groups (p = 0.056) in favor of placebo. On analysis of inflammatory and metabolic markers, a statistically significant negative correlation was noted between change in leptin levels and change in depression scores in the pioglitazone group (r = -0.61, p = 0.047) but not in the placebo group, the significance of which is unclear as the study failed to demonstrate antidepressant efficacy of pioglitazone over placebo. No serious adverse effects were reported, and pioglitazone was well-tolerated.

LIMITATIONS

small sample size with inadequate power, concomitant use of other psychotropic medications, and lack of statistical adjustment for multiple testing.

CONCLUSION

Current study does not support the antidepressant efficacy of pioglitazone in the treatment of bipolar depression. (240 words).

Leptin in depression: a potential therapeutic target

Leptin, produced and secreted by white adipose tissue, plays a critical role in regulating body weight, food intake, and energy metabolism. Recently, several studies have identified an underlying role for leptin in regulation of mood and cognition via regulation of synaptic changes in the brain that have been associated with antidepressant-like actions. Brain neural plasticity occurs in response to a range of intrinsic and extrinsic stimuli, including those that may mediate the effects of antidepressants. Neural plasticity theories of depression are thought to explain multiple aspects of depression and the effects of antidepressants. It is also well documented that leptin has effects on neural plasticity. This review summarizes the recent literature on the role of leptin in neural plasticity in order to elaborate the possible mechanism of leptin’s antidepressant-like effects. Recent findings provide new insights into the underlying mechanisms of neural plasticity in depression. Leptin may influence these mechanisms and consequently constitute a possible target for novel therapeutic approaches to the treatment of depression.

Leptin and adiponectin levels in major depressive disorder: A systematic review and meta-analysis

OBJECTIVES

To explore differences in adipokine levels (i.e., leptin and adiponectin levels) between adults with Major Depressive Disorder (MDD) and healthy controls (HC), and to discuss the possible role of adipokine regulation in the development and progression of MDD.

METHODS

A systematic review and meta-analysis were conducted based on the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. A systematic search was conducted for all English and Chinese peer-reviewed articles from inception to November 2017. A random effects model was used to calculate the standardized mean difference (SMD) of leptin and/or adiponectin levels in subjects diagnosed with MDD versus HC within a 95% confidence interval (CI).

RESULTS

Thirty-three studies were included in this meta-analysis. In total, 4,372 (52.3%) subjects with MDD and 3,984 (47.7%) HC were compared. We identified significant lower adiponectin levels in MDD compared to HC with a small effect size (ES) (SMD = -0.25; 95% CI: -0.48, -0.02; P < 0.001). However, no significant difference was observed in leptin levels between MDD subjects and HC (SMD = 0.13; 95% CI: -0.06, 0.31; P = 0.170). The heterogeneity in the results of our meta-analysis could not be completely explained by dividing subjects into subgroups. Results from subgroup analyses suggested that studies involving samples with BMI ≥ 25 had lower adiponectin levels in subjects with MDD compared to HC, and older age samples (i.e., age ≥ 40) with BMI ≥ 25 had both higher leptin levels and lower adiponectin levels in MDD subjects as compared to HC.

LIMITATIONS

The heterogeneity of included studies, small sample sizes, and potential publication bias were significant limitations.

CONCLUSIONS

The current systematic review and meta-analysis indicated that lower adiponectin levels may be associated with MDD. Moreover, the results suggest that males expressing lower adiponectin and leptin levels have an increased likelihood of developing MDD. Future studies should aim to investigate the manifestation of depressive phenotypes in older, obese populations with altered metabolic profiles resulting from adipokine dysregulation. The review has been registered with PROSPERO (registration number CRD42018082733).

The association between depressive symptoms and insulin resistance, inflammation and adiposity in men and women

INTRODUCTION

Depression has been shown to be associated with elevated leptin levels, low-grade inflammation and insulin resistance. These derangements are often measured in mixed gender cohorts despite the different body compositions and hormonal environments of men and women and gender-specific prevalence and responses to depression.

METHODS

A cross-sectional analysis was carried out on a cohort of 639 participants from the ADDITION-Leicester dataset to assess differences in markers of diabetes risk, cardiovascular risk and inflammation in depressed and non-depressed individuals. Depressive symptoms were determined using the WHO (Five) well-being index. Multivariate linear and logistic regression analyses were adjusted for age, sex, ethnicity, body mass index, smoking, social deprivation and activity levels for continuous and binary variables respectively. Further analysis included stratifying the data by gender as well as assessing the interaction between depression and gender by including an interaction term in the model.

RESULTS

Women with depressive symptoms had a 5.3% larger waist circumference (p = 0.003), 28.7% higher HOMA IR levels (p = 0.026), 6.6% higher log-leptin levels (p = 0.01) and 22.37% higher TNF-α levels (p = 0.015) compared with women without. Conversely, depressive symptoms in men were associated with 7.8% lower body fat % (p = 0.015) but 48.7% higher CRP levels (p = 0.031) compared to men without. However, interaction analysis failed to show a significant difference between men and women.

CONCLUSIONS

Depressive symptoms are associated with metabolic derangements. Whilst women tended to show elevations in biomarkers related to an increased risk of type 2 diabetes (HOMA IR, leptin and TNF-α), men showed a marked increase in the cardiovascular disease risk biomarker CRP. However, perhaps due to the cohort size, interaction analysis did not show a significant gender difference.

Patatin-like phospholipase domain-containing protein 3 (PNPLA3): A potential role in the association between liver disease and bipolar disorder

OBJECTIVE

Due to the increased prevalence of liver disease in patients with bipolar disorder, we examined the potential role of the patatin-like phospholipase domain-containing protein 3 (PNPLA3) variant among individuals with bipolar disorder and those with no mood disorder.

METHODS

We used the National Health and Nutrition Examination Survey (NHANES) database (aged 15-39 years) to identify a group of individuals with a bipolar diagnosis and a control group of individuals with no mood disorder. A total of 1931 individuals were randomly selected, one from each family containing information on the PNPLA3 genotype to be used in the analysis.

RESULTS

Analyses revealed individuals with the recessive variant genotype (MM) had an adjusted odds ratio for bipolar disorder of about 4.6 compared to individuals with either IM or II genotypes of the PNPLA3 variant.

LIMITATIONS AND CONCLUSIONS

Limitations of this study include the use of a lay-administered survey in for diagnosis of bipolar disorder in NHANES. The association between the PNPLA3 variant and bipolar disorder may help guide further work on medication effectiveness, treatment options, prevention approaches, and understanding potential medication side effects among specific subgroups of individuals with the MM genotype.

The Effects of High-fat-diet Combined with Chronic Unpredictable Mild Stress on Depression-like Behavior and Leptin/LepRb in Male Rats

Leptin plays a key role in the pathogenesis of obesity and depression via the long form of leptin receptor (LepRb). An animal model of comorbid obesity and depression induced by high-fat diet (HFD) combined with chronic unpredictable mild stress (CUMS) was developed to study the relationship between depression/anxiety-like behavior, levels of plasma leptin and LepRb in the brains between four groups of rats, the combined obesity and CUMS (Co) group, the obese (Ob) group, the CUMS group and controls. Our results revealed that the Co group exhibited most severe depression-like behavior in the open field test (OFT), anxiety-like behavior in elevated plus maze test (EMT) and cognitive impairment in the Morris water maze (MWM). The Ob group had the highest weight and plasma leptin levels while the Co group had the lowest levels of protein of LepRb in the hypothalamus and hippocampus. Furthermore, depressive and anxiety-like behaviors as well as cognitive impairment were positively correlated with levels of LepRb protein and mRNA in the hippocampus and hypothalamus. The down-regulation of leptin/LepRb signaling might be associated with depressive-like behavior and cognitive impairment in obese rats facing chronic mild stress.

Mortality in Women With Anorexia Nervosa: The Role of Comorbid Psychiatric Disorders

OBJECTIVE

To investigate mortality in anorexia nervosa (AN) with a psychiatric comorbidity.

METHODS

Using Swedish registers, data for 8069 female inpatients with AN were retrospectively collected for 1973-2010. Mortality patterns were assessed using standardized mortality ratios (SMRs), Cox regression-derived hazard ratios, and incidence rate ratios. A control cohort of 76,995 women was used.

RESULTS

Patients with AN and a psychiatric comorbidity had higher mortality rates did than those without a comorbidity. The SMRs for patients with AN and a psychiatric comorbidity were 5.4 (95% confidence interval [CI] = 4.6-6.4) and 18.1 (95% CI = 15.2-21.3) for natural and unnatural causes of death, respectively. The SMRs for patients with AN without a comorbidity were 2.8 (95% CI = 2.3-3.5) and 3.1 (95% CI = 2.2-4.1) for natural and unnatural causes of death, respectively. The adjusted hazard ratios for mortality from natural or unnatural causes were 2.0 (95% CI = 1.5-2.7) and 5.7 (95% CI = 3.9-8.2), respectively. Incidence rate ratios comparing patients with AN and controls, both with psychiatric comorbidities, suggest a negative synergistic effect of comorbid AN and psychiatric disorder on mortality, which was greater for unnatural causes of death.

CONCLUSIONS

Mortality in patients with AN was greater in the presence of a psychiatric comorbidity, and even more pronounced for unnatural causes of death and suicides. Substance abuse, especially alcohol use disorder, increased mortality from natural causes of death. These findings highlight the need for early detection and treatment of psychiatric comorbidity in AN, to potentially improve long-term outcomes.

The Association Between Serum Leptin Levels and Post-Stroke Depression: A Retrospective Clinical Study

Objective

To investigate the question of whether serum leptin levels might be associated with post-stroke depression.

Methods

We studied 130 patients who experienced a first episode of stroke of more than three months' duration, without any previous history of depression or speech disorders. Data were collected regarding the patient demographics, depressive mood (Diagnostic and Statistical Manual of Mental Disorders 4th edition [DSM-IV] criteria and Beck Depression Inventory) and serum leptin levels measured by an enzyme-linked immunosorbent assay (ELISA). In addition, the Korean version of Modified Barthel Index (K-MBI) and Korean version of Mini-Mental State Examination (K-MMSE) were used to assess the subjects' independence, in regard to the activities of daily living and cognition. A statistical analysis was performed to determine differences the serum leptin levels between patients with depression and those without depression, and to determine the difference in the MBI and K-MMSE scores between the groups separated according to the serum leptin levels.

Results

Higher serum leptin levels were observed in patients with depression, compared with those without depression (38.5 ng/mL [range, 25.1-59.2 ng/mL] vs. 8.2 ng/mL [range, 4.9-17.8 ng/mL]; p<0.01. The serum leptin level showed an association with depression (odds ratio, 1.21; 95% confidence interval, 1.01-1.45; p=0.021). The K-MMSE and K-MBI improvement scores were lower, with statistical significance, in the group with the highest leptin level (>30 mg/dL), compared to the other two groups.

Conclusion

High serum leptin levels are associated with depression after stroke, and patients with elevated serum leptin levels were disadvantaged in regard to functional and cognitive outcomes.