Plasma profiles of carnitine and acylcarnitines in first-diagnosed, drug-naïve patients with depression: A case-control analysis.

Acylcarnitines, critical intermediates in mitochondrial fatty acid β-oxidation, may serve as promising diagnostic biomarkers for depression. However, current research on depression-associated acylcarnitine metabolism exhibits significant heterogeneity in both methodology and findings. The case-control study included a total of 100 first-diagnosed, drug-naïve depressed patients and 50 healthy controls matched with age, sex and body mass index. Plasma acylcarnitines were identified using ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry, and then quantified by the liquid chromatography-tandem mass spectrometry. This analysis quantified 33 acylcarnitine species and carnitine in plasma samples. For patients with depression, most medium-chain acylcarnitines and C0/ (C16:0 +C18:0) ratio (an index of carnitine palmitoyltransferase I) were decreased, while long-chain acylcarnitine levels were increased. The changes in levels of acylcarnitines C10:1, C11:0, C18:1 and C20:2 remain significant after false discovery rate correction. Receiver operating characteristic curve analysis identified three dysregulated acylcarnitines C11:0, C20:2, C18:1 as potential depression biomarkers, with their combined panel showing promising discriminative power (area under the curve =0.831). These findings revealed significant alterations in acylcarnitine metabolism associated with depression, suggesting their potential utility as metabolic biomarkers. While the observed dysregulation provides new insights into depression pathophysiology, further studies will need to establish diagnostic applicability through mechanistic investigation and clinical validation.