Plasma Neuropeptide-S Levels in Populations Diagnosed with Generalized Anxiety Disorder: A Controlled Study

Abstract

Introduction: Neuropeptide S (NPS) is a novel neuropeptide reported to be involved in fear-and stress-related conditions and their corresponding neuroendocrine processes. The aim of this study was to compare the plasma NPS levels in patients suffering from generalized anxiety disorder (GAD) and those of healthy controls.

Methods: A total of 40 subjects diagnosed with GAD and 40 healthy controls were recruited in the study. The Hamilton Anxiety Scale (HAM-A), Generalized Anxiety Disorder-7 (GAD-7), and Hamilton Depression Scale (HAM-D) were administered to all participants to determine the severity of participants' anxiety and concomitant depressive symptoms. The plasma NPS levels were measured from the fasting venous blood samples obtained from each participant.

Results: The median plasma NPS level was found to be significantly higher in the GAD group in comparison to the control group (28.8 pg/mL as against 19.1 pg/mL, p=0.01). A significant positive correlation was observed between the plasma NPS levels and HAM-A scores (rs=0.23, p=0.04) as well as the GAD-7 scores (rs=0.28, p=0.01). The p-value obtained from the correlation analysis between the plasma NPS levels and HAM-D scores was 0.052. A receiver operating characteristic (ROC) analysis revealed that the plasma NPS levels could enable the identification of GAD with 67.5% sensitivity and 62.5% specificity, when the cut-off value was determined as 25.06 pg/mL.

Conclusions: Our results support the view that plasma NPS levels, which has demonstrated anxiolytic effects on the central nervous system, is related to the severity of anxiety in GAD and could be considered as a candidate marker for the identification of GAD.

Keywords: GAD; HPA; generalized anxiety; inflammation; neuropeptide-S.

Figure 1

A correlation analysis between plasma NPS levels and anxiety scores; a significant positive correlation was observed between plasma NPS levels and both HAM-A and GAD-7 scores.

Figure 2

A ROC analysis to establish a cut-off value for plasma NPS levels in the identification of GAD. The ROC analysis revealed that plasma NPS levels could allow the identification of GAD with the cut-off value 25.06 pg/mL, with 67.5% sensitivity and 62.5% specificity. The remaining values were as indicated: Area Under the Ccurve (AUC)=0.658, 95%; confidence interval (CI)=0.543–0.760; P=0.009; ROC: A Receiver Operating Characteristic, GAD: Generalized Anxiety Disorder.