Objective: ​​​​​​To determine whether peripheral neurodegeneration-related biomarker levels differ between patients with Parkinson’s disease (PD) with and without depression and to identify biomarkers associated with depressive symptoms.

Background: Depression is one of the most common neuropsychiatric complications, affecting approximately 30–40% of patients with PD. Brain-derived neurotrophic factor (BDNF) is a key regulator of synaptic plasticity, neuronal survival, and neural circuit remodeling. Reduced neurotrophic support may contribute to dopaminergic neurodegeneration and may also influence non-motor manifestations of PD. Experimental and clinical studies suggest that dysregulation of BDNF is involved in the pathophysiology of depression.

Method: Patients with early-stage PD were recruited from the Hallym PD registry, which contains prospectively collected demographic, clinical, imaging, and laboratory data. Depression was evaluated using the depression subscale of the Hospital Anxiety and Depression Scale.

Serum concentrations of BDNF were measured using the Simoa® BDNF Discovery Assay. To simultaneously assess markers reflecting neurodegeneration, serum levels of GFAP, NfL, total tau, and UCHL1 were measured using the Simoa® Neurology 4-Plex A Advantage Kit. All biomarker levels were log-transformed prior to analysis.

Results: A total of 87 patients with PD and 37 healthy controls (HC) were included. The sample included 56 patients who met the criteria for depression. Mean age did not differ significantly between groups; however, the HC group had a higher proportion of female participants than the PD group without depression (70.3% vs. 38.7%, p = 0.032). BDNF levels were significantly lower in the PD group with depression than in both the PD group without depression and the HC group (p = 0.025), whereas other biomarkers did not differ significantly among the three groups. This difference remained significant after adjustment for age and sex. In the PD group, BDNF levels were independently associated with depression after adjustment for age, sex, disease duration, cognitive function, and PD severity (B = −1.597, p = 0.044; OR 0.202; 95% CI, 0.043–0.958).

Conclusion: Peripheral BDNF levels are independently associated with depressive symptoms in PD and may serve as a biomarker of depression in PD, consistent with the proposed neurotrophic role of BDNF.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/brain-derived-neurotrophic-factor-as-a-biomarker-of-depression-in-parkinsons-disease/