Leptin is a multifunctional hormone secreted from adipose tissue, which plays a core role in regulating energy intake and expenditure. Evidence has demonstrated that leptin receptors are located in brain areas involved in emotional processing, and major depressive disorder (MDD) is characterized by dysfunction of emotional processing. Taken together, these features suggest that leptin may play a potential role in the pathophysiology of MDD. However, the precise roles of leptin in modulating depressive symptoms in MDD remain unclear.

Participants [18 drug-naïve MDD patients, 15 unaffected first-degree relatives of MDD patients (FDR-MDD), and 40 healthy controls] completed clinical assessments and provided blood samples for measurement of leptin levels. We evaluated the effect of leptin on clinical status (MDD or FDR-MDD) and symptomatic dimensionalities of MDD using mediation analysis.

We found that leptin was increased in MDD patients and this only predicted “somatic anxiety” symptoms. Furthermore, leptin was a significant and indirect mediator of the association between clinical status (MDD or FDR-MDD) and “somatic anxiety” symptoms.

Our finding that leptin was a significant and indirect mediator of clinical status (MDD or FDR-MDD) and “somatic anxiety” symptoms suggests that leptin may indirectly affect somatic depressive symptoms in MDD. Our findings may provide a theoretical basis for novel clinical interventions in MDD.

瘦素是一种由脂肪组织分泌的多功能激素，在调节能量摄入和消耗方面起着核心作用。有证据表明，瘦素受体位于参与情绪处理的大脑区域，重度抑郁症（MDD）的特点是情绪处理功能障碍。总之，这些特征表明瘦素可能在 MDD 的病理生理学中发挥潜在作用。然而，瘦素在调节 MDD 抑郁症状中的确切作用仍不清楚。

参与者 [18 名未用药 MDD 患者、15 名未受影响的 MDD 患者一级亲属 (FDR-MDD) 和 40 名健康对照] 完成了临床评估并提供了用于测量瘦素水平的血液样本。我们使用中介分析评估了瘦素对临床状态（MDD 或 FDR-MDD）和 MDD 症状维度的影响。

我们发现 MDD 患者的瘦素增加，这只能预测“躯体焦虑”症状。此外，瘦素是临床状态（MDD 或 FDR-MDD）与“躯体焦虑”症状之间关联的重要间接介质。

我们发现瘦素是临床状态（MDD 或 FDR-MDD）和“躯体焦虑”症状的重要和间接介质，这表明瘦素可能间接影响 MDD 的躯体抑郁症状。我们的研究结果可能为 MDD 的新型临床干预提供理论基础。