Elevated serum leptin is associated with attenuated reward anticipation in major depressive disorder independent of peripheral C-reactive protein levels

Blunted stimulus-preceding negativity during reward anticipation in major depressive disorder

BACKGROUND

Reward processing dysfunction is a core characteristic of major depressive disorder (MDD), yet event-related potential (ERP) research in MDD has predominantly focused on reward receipt as opposed to anticipation. The stimulus-preceding negativity (SPN) ERP reflects anticipatory brain processing. This study examines whether individuals with MDD exhibit deficits during reward anticipation as evidenced by altered SPN amplitude.

METHODS

We assessed prefeedback-SPN amplitudes during a monetary incentive delay (MID) task in individuals with MDD (n = 142, 99 with comorbid anxiety disorders [MDD + ANX]) compared to Controls (n = 37). A mixed analysis of variance was performed on prefeedback-SPN amplitude and behavioral measures, with group (MDD, MDD + ANX, Control) as the between-subjects factor, and feedback (gain, loss) and electrode (F3, F4, Fz, C3, C4, Cz, P3, P4, Pz) as within-subjects factors.

RESULTS

A group main effect revealed faster reaction times for the Control group than MDD and MDD + ANX groups. A group x feedback interaction indicated that the MDD subgroup had smaller prefeedback-SPN amplitudes than MDD + ANX and Control groups when anticipating gain feedback. Additionally, individuals with current MDD, irrespective of past MDD and comorbid anxiety, exhibited smaller SPN amplitudes than Controls prior to gain feedback.

LIMITATIONS

The MID paradigm, designed for functional magnetic resonance imaging (fMRI) data acquisition, lacks optimization for ERP analysis. Moreover, the clinical groups included more females than the Control group.

CONCLUSIONS

Reduced resource allocation to reward anticipation may differentiate MDD from MDD + ANX and Control groups. Further investigation of the neural mechanisms of distinct MDD phenotypes is warranted.

Leptin's Inverse Association With Brain Morphology and Depressive Symptoms: A Discovery and Confirmatory Study Across 2 Independent Samples

BACKGROUND

Major depressive disorder has a complex, bidirectional relationship with metabolic dysfunction, but the neural correlates of this association are not well understood.

METHODS

In this cross-sectional investigation, we used a 2-step discovery and confirmatory strategy utilizing 2 independent samples (sample 1: 288 participants, sample 2: 196 participants) to examine the association between circulating indicators of metabolic health (leptin and adiponectin) and brain structures in individuals with major depressive disorder.

RESULTS

We found a replicable inverse correlation between leptin levels and cortical surface area within essential brain areas responsible for emotion regulation, such as the left posterior cingulate cortex, right pars orbitalis, right superior temporal gyrus, and right insula (standardized beta coefficient range: -0.27 to -0.49, puncorrected < .05). Notably, this relationship was independent of C-reactive protein levels. We also identified a significant interaction effect of leptin levels and diagnosis on the cortical surface area of the right superior temporal gyrus (standardized beta coefficient = 0.26 in sample 1, standardized beta coefficient = 0.30 in sample 2, puncorrected < .05). We also observed a positive correlation between leptin levels and atypical depressive symptoms in both major depressive disorder groups (r = 0.14 in sample 1, r = 0.29 in sample 2, puncorrected < .05).

CONCLUSIONS

The inverse association between leptin and cortical surface area in brain regions that are important for emotion processing and leptin's association with atypical depressive symptoms support the hypothesis that metabolic processes may be related to emotion regulation. However, the molecular mechanisms through which leptin may exert these effects should be explored further.

Altered leptin level in autism spectrum disorder and meta-analysis of adipokines

BACKGROUND

Increasing evidence suggests that leptin is involved in the pathology of autism spectrum disorder (ASD). In this study, our objective was to investigate the levels of leptin in the blood of children with ASD and to examine the overall profile of adipokine markers in ASD through meta-analysis.

METHODS

Leptin concentrations were measured using an enzyme-linked immunosorbent assay (ELISA) kit, while adipokine profiling, including leptin, was performed via meta-analysis. Original reports that included measurements of peripheral adipokines in ASD patients and healthy controls (HCs) were collected from databases such as Web of Science, PubMed, and Cochrane Library. These studies were collected from September 2022 to September 2023 and followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Standardized mean differences were calculated using a random effects model for the meta-analysis. Additionally, we performed meta-regression and explored heterogeneity among studies.

RESULTS

Our findings revealed a significant increase in leptin levels in children with ASD compared to HCs (p = 0.0319). This result was consistent with the findings obtained from the meta-analysis (p < 0.001). Furthermore, progranulin concentrations were significantly reduced in children with ASD. However, for the other five adipokines analyzed, there were no significant differences observed between the children with ASD and HCs children. Heterogeneity was found among the studies, and the meta-regression analysis indicated that publication year and latitude might influence the results of the meta-analysis.

CONCLUSIONS

These findings provide compelling evidence that leptin levels are increased in children with ASD compared to healthy controls, suggesting a potential mechanism involving adipokines, particularly leptin, in the pathogenesis of ASD. These results contribute to a better understanding of the pathology of ASD and provide new insights for future investigations.

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.