Differences in Plasma BDNF Levels Between Chronic Primary Musculoskeletal Pain, Fibromyalgia Syndrome, and Asymptomatic Subjects: A Cross-Sectional Study.

This cross-sectional study compared plasma brain-derived neurotrophic factor (BDNF) levels among chronic primary musculoskeletal pain patients, chronic widespread pain patients, and asymptomatic controls. The study included 126 participants aged 18-65, divided into three groups of 42 each. Pain intensity was assessed using a Numeric Rating Scale (NRS), and plasma BDNF levels were measured via ELISA. Differences between groups were evaluated using ANOVA with 2000 bootstrap resamples and a bias-corrected and accelerated method. Results showed significantly higher plasma BDNF levels in chronic widespread pain patients (mean difference [MD] = 0.44; 95% CI = 0.28, 0.62; p < .001) compared to controls, and higher than in chronic primary musculoskeletal pain patients (MD = 0.83; 95% CI = 0.64, 1.02; p < .001). Chronic primary musculoskeletal pain patients had lower plasma BDNF levels compared to controls (MD = -0.39; 95% CI = -0.54, -0.24; p < .001). No significant correlations were observed between plasma BDNF levels and clinical variables. These findings suggest the potential of BDNF as a biomarker to differentiate chronic primary pain conditions.