BACKGROUND A subset of patients with Major Depressive Disorder (MDD) have shown differences relative to healthy controls in blood inflammatory and immune markers. Meanwhile, MDD and comorbid obesity appear to present with distinct biological and symptom characteristics, categorised as "atypical" or "immunometabolic" depression, although the relevant underlying biological mechanisms are still uncertain. Therefore, this exploratory study aimed to better characterise the relationship between peripheral blood immune markers and symptoms of MDD, as well as the extent to which body mass index (BMI) may alter this relationship. METHODS Linear regression analyses were performed between selected baseline characteristics including clinical scales and blood inflammatory markers in participants with MDD (n = 119) enrolled in the PREDDICT randomised controlled trial (RCT), using age, sex and BMI as covariates, and then stratified by BMI status. Specifically, the Montgomery-Åsberg Depression Rating Scale (MADRS) for symptom severity, Clinical Global Impression scale (CGI) for functional impairment, Oxford Depression Questionnaire (ODQ) for emotional blunting, and THINC integrated tool (THINC-it) for cognitive function were considered as clinical measures. RESULTS There was a significant association between basophil count and THINC-it Codebreaker mean response time (associated with complex attention, perceptual motor, executive function, and learning and memory abilities) in overweight individuals and with THINC-it Trails total response time (associated with executive function ability) in moderately obese individuals, when controlling for age, sex, and years of education. No correlation was found between any tested blood markers and MADRS, CGI or ODQ clinical measures, regardless of BMI. DISCUSSION Although the present study is exploratory, the results suggest that targeting of the immune system and of metabolic parameters might confer benefits, specifically in patients with high BMI and experiencing cognitive impairment associated with MDD. TRIAL REGISTRATION Australian New Zealand Clinical Trials Registry (ANZCTR), ACTRN12617000527369p. Registered on 11 April 2017.

中文翻译：

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重度抑郁症中血液免疫标志物与认知症状严重程度之间关联的探索性研究：按体重指数状态分层

背景 患有重度抑郁症 (MDD) 的一部分患者在血液炎症和免疫标志物方面与健康对照者相比存在差异。同时，MDD 和合并肥胖似乎呈现出不同的生物学和症状特征，被归类为“非典型”或“免疫代谢”抑郁症，尽管相关的潜在生物学机制仍不确定。因此，这项探索性研究旨在更好地表征外周血免疫标志物与 MDD 症状之间的关系，以及体重指数 (BMI) 可能改变这种关系的程度。方法 在参加 PREDDICT 随机对照试验 (RCT) 的 MDD 参与者（n = 119）的选定基线特征（包括临床量表和血液炎症标志物）之间进行线性回归分析，使用年龄、性别和 BMI 作为协变量，然后按BMI 状态。具体而言，用于症状严重程度的蒙哥马利-奥斯伯格抑郁量表 (MADRS)、用于功能障碍的临床总体印象量表 (CGI)、用于情绪迟钝的牛津抑郁问卷 (ODQ) 和用于认知功能的 THINC 综合工具 (THINC-it) 是被视为临床措施。结果 嗜碱性粒细胞计数与 THINC-it Codebreaker 平均反应时间（与复杂注意力、知觉运动、执行功能、在控制年龄、性别和受教育年限的情况下，超重个体和 THINC-it 跟踪中度肥胖个体的总反应时间（与执行功能能力相关）。无论BMI如何，在任何测试的血液标志物与MADRS、CGI或ODQ临床测量之间均未发现相关性。讨论 尽管本研究是探索性的，但结果表明，针对免疫系统和代谢参数可能会带来益处，特别是对于高 BMI 和经历与 MDD 相关的认知障碍的患者。试验注册澳大利亚新西兰临床试验注册 (ANZCTR)，ACTRN12617000527369p。2017 年 4 月 11 日注册。