Elevated Serum Histamine N‐Methyltransferase Levels Are Associated With the Pathophysiology of Major Depressive Disorder: A Case–Control Study

Major depressive disorder (MDD) is a common neuropsychiatric disorder with persistent low mood, feelings of weakness, and a lack of interestin daily tasks. Histamine N-methyltransferase (HNMT) protein is involved in the inactivation process of histamine in human physiology. Here, we aimed to assess the role of HNMT in the pathophysiology and development of MDD. This case-control study included 56 MDD patients and 32 healthy controls (HCs) by matching age, sex, body mass index (BMI), and other sociodemographic characteristics. A clinical psychiatrist assessed the MDD patients and HCs according to the DSM-5 criteria. We used the Ham-D scale in evaluating the severity of depressive symptoms. We used ELISA kits to estimate serum HNMT levels. We observed elevated serum HNMT concentration in MDD patients (29.25 ± 5.34 pg/ml) compared with HCs (23.13 ± 2.10 pg/ml). Serum HNMT levels and Ham-D scores are positively correlated with each other in MDD patients (r = 0.632, p < 0.001). Also, the receiver operating characteristic curve analysis illustrated a significant diagnostic value for HNMT with the area under the curve (AUC = 0.916) at p < 0.001. The promising findings from this study anticipate that the elevated serum levels of HNMT may be associated with the pathophysiology and mechanism of MDD. We recommend further interventional studies to produce more precise and accurate results on this biomarker in depression.