biostudies-literatureUnknown17Zhao Z<h4>Background</h4>Brain-derived neurotrophic factor (BDNF) is essential for regulating neuronal proliferation and survival in neurodegenerative diseases, including Parkinson's disease (PD). However, Studies on BDNF levels in peripheral blood and cerebrospinal fluid (CSF) have inconsistent results. Therefore, this study aimed to examine BDNF levels in patients with PD and to explore their correlation with non-motor symptoms.<h4>Methods</h4>Four databases (PubMed, Embase, Cochrane Library, and CNKI) were searched for eligible studies. The quality of the included studies was assessed using the Newcastle-Ottawa Scale (NOS). Standardized mean differences (SMDs) with 95% confidence intervals (CIs) were calculated using Stata version 14.0, applying either a fixed-effect or a random-effects modelFrontiers in aging neuroscience1620172https://www.ebi.ac.uk/biostudies/studies/S-EPMC12492986biostudies-literatureAssociation of brain-derived neurotrophic factor in blood and cerebrospinal fluid with Parkinson's disease and non-motor symptoms of Parkinson's disease: a systematic review and meta-analysis of 6655 participants.PMC12492986Liu YLiu MZhao ZSun JTong DfalseAssociation of brain-derived neurotrophic factor in blood and cerebrospinal fluid with Parkinson's disease and non-motor symptoms of Parkinson's disease: a systematic review and meta-analysis of 6655 participants.<h4>Background</h4>Brain-derived neurotrophic factor (BDNF) is essential for regulating neuronal proliferation and survival in neurodegenerative diseases, including Parkinson's disease (PD). However, Studies on BDNF levels in peripheral blood and cerebrospinal fluid (CSF) have inconsistent results. Therefore, this study aimed to examine BDNF levels in patients with PD and to explore their correlation with non-motor symptoms.<h4>Methods</h4>Four databases (PubMed, Embase, Cochrane Library, and CNKI) were searched for eligible studies. The quality of the included studies was assessed using the Newcastle-Ottawa Scale (NOS). Standardized mean differences (SMDs) with 95% confidence intervals (CIs) were calculated using Stata version 14.0, applying either a fixed-effect or a random-effects model2025-01-01T00:00:00Z20252026-06-04T05:21:53.992Z2026-05-05T03:12:58.904ZS-EPMC124929864104953510.3389/fnagi.2025.1620172