The interplay of niacin skin flush response with plasma MDA, TNOS, iNOS and clinical symptom severity in chronic schizophrenia

BACKGROUND: Multiple studies have consistently reported elevated oxidative stress and an impaired niacin skin flush response in patients with schizophrenia. This study aimed to compare differences in oxidative stress levels and the niacin skin flush response between patients stratified by the intensity of their response and healthy controls, and to analyze the correlations among oxidative stress markers, the niacin response, and clinical symptoms within the different response subgroups. METHODS: A cross-sectional case-control design was employed. Fifty patients with chronic schizophrenia and 50 demographically matched healthy controls were enrolled. Plasma levels of malondialdehyde (MDA), total nitric oxide synthase (TNOS), and inducible nitric oxide synthase (iNOS) were measured in all participants, and the niacin skin flush response was assessed. Symptom severity in patients was rated using the Positive and Negative Syndrome Scale (PANSS). Based on the intensity of the niacin response, patients were further divided into high-response and low-response subgroups. Regression analysis was used to explore the associations among oxidative stress indicators, the niacin response, and clinical symptoms. RESULTS: MDA levels were significantly higher in the patient group than in the control group, whereas both TNOS and iNOS levels were significantly lower. The pattern of associations among oxidative stress markers, the niacin skin flush response, and clinical symptoms differed across response subgroups. These relationships may be influenced by factors such as sex, body mass index (BMI), age, and the dosage of antipsychotic medication. CONCLUSION: Patients with chronic schizophrenia exhibit abnormalities in oxidative stress and show individual variability in the niacin skin flush response. The intensity of the niacin response may be associated with factors such as sex, BMI, age, and medication, leading to significant differences in the relationships among variables across subgroups in regression analysis. The results suggest that oxidative stress may be involved in the pathophysiological processes of schizophrenia, and that niacin sensitivity may reflect the level of oxidative stress in the body and correlate with different clinical symptomatic profiles. CLINICAL TRIAL: No applicable.