BDNF as a biomarker for insomnia in hemodialysis patients: influence of hypnotic medication use.

OBJECTIVE: Though insomnia is highly prevalent in patients undergoing maintenance hemodialysis (HD), it is often underdiagnosed. Brain-derived neurotrophic factor (BDNF), a neurotrophin involved in sleep regulation and neuropsychiatric function, has emerged as a potential biomarker for insomnia. However, BDNF levels may be influenced by confounding factors, such as hypnotic medications and dialysis-related clearance. This study aimed to evaluate the relationship between BDNF, sleep quality, medication use, and dialysis in HD patients. METHODS: We conducted a single-center cross-sectional study involving 73 maintenance HD patients. Insomnia was diagnosed according to International Classification of Sleep Disorders-3 (ICSD-3) criteria, and sleep quality was assessed using the PSQI. Pre-dialysis and post-dialysis blood samples were collected to measure plasma BDNF concentrations by enzyme-linked immunosorbent assay. Standardized BDNF levels were used in logistic regression analyses. RESULTS: Compared with patients without insomnia, those with insomnia had higher pre-dialysis BDNF levels (6892 ± 2778 vs. 5561 ± 2552 pg/mL, p = 0.04). Post-dialysis BDNF levels remained higher in the insomnia group although the difference was not statistically significant. Spearman's correlation analysis revealed that BDNF levels before and after dialysis were positively correlated with hypnotic medication use (rs = 0.31 and 0.33, p = 0.01 and 0.01, respectively), but were not significantly associated with total PSQI scores. Stratified analyses further revealed that among participants not using hypnotic medications, higher BDNF levels (both pre- and post-dialysis) were independently associated with a lower risk of poor sleep quality (pre-dialysis: OR = 0.43, 95% CI 0.19-0.95, p = 0.04; post-dialysis: OR = 0.37, 95% CI 0.15-0.93, p = 0.04). However, no similar association was observed in the medicated group. Scatter plots also suggested distinct distribution patterns and differing directions of correlation between the two groups. CONCLUSION: BDNF levels appear to be associated with sleep quality in HD patients not using hypnotic medications, and this association may be modified by hypnotic medication use. Accordingly, BDNF may represent a putative biomarker for insomnia in HD patients without hypnotic medications.