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.