Investigation of Factors Affecting Spontaneous Eye Blink Frequency in Parkinson's Disease

Abstract

Objective: Parkinson's disease (PD) is a neurodegenerative movement disorder with dopaminergic loss in the brain. Frequency of spontaneous eye blink (FSEB) is also known to be a marker that provides information about the brain's dopamine sources. In this context, we designed this study to reveal the frequency of spontaneous eye blink in Parkinson's patients from Turkey and to investigate the factors affecting this frequency. And also, we would like to show the power of FSEB in the differential diagnosis of PD clinical subtypes. Materials and Methods: For our study, 168 patients who applied Koc University Neurology Department between 2016 July and 2021 July and had at least one-minute examination video were retrospectively scanned. One hundred nineteen patients diagnosed with PD from their files were included in the study. Analyzes were performed for the relationship between the patients' number of spontaneous eye blinks in 1 minute and the follow-up information. Results: The median age of the patients participating in our study was 60 (52-69) years. Forty-one (35%) were women. The frequency of spontaneous eye blink of our group was measured as 12 (6-25)/min. In regression analysis for blink frequency, age was found to be the predictor when evaluated together with sex, disease duration, clinical subtype, and l-dopa equivalent dose (P=0.021). Conclusion: As a result, the frequency of spontaneous eye blink decreases with age. The frequency of spontaneous blink in patients with Parkinson's disease is associated with age, regardless of gender, disease duration, disease clinical subtype, and the l-dopa equivalent dose of dopaminergic drugs used. Therefore, FSEB cannot be used as a potent biomarker for categorization in the PD population.