Seborrheic Dermatitis Is Related to Motor Symptoms in Parkinson's Disease.

Background and purpose: Parkinson's disease (PD) patients present with numerous motor and nonmotor symptoms. Seborrheic dermatitis (SD) is reported in 18.6%-59% of PD patients. However, the etiology of SD in PD patients remains unknown. The aim of this study was to determine how motor and nonmotor symptoms, age, sex, and levodopa-equivalent daily dose (LEDD) influence the appearance and severity of SD in PD patients, and then discuss about SD possible etiology based on the obtained results.

Methods: Motor symptoms were evaluated using the Unified Parkinson's Disease Rating Scale part III and nonmotor symptoms were evaluated using the Parkinson's Disease Sleep Scale, Scales for Outcomes in Parkinson's Disease-Autonomic Dysfunction, and Non-Motor Symptoms Questionnaire. LEDD was calculated and demographic data on age, sex, disease duration, and symptoms of SD prior to a PD diagnosis were collected. A dermatologist evaluated the skin for SD using the Seborrhea Area and Severity Index.

Results: SD was present in 36.1% of the PD patients. There were positive correlations between age, motor-symptoms severity, and SD. After adjusting for age, disease duration, and sex, there remained a positive correlation between the severity of motor symptoms and SD. Patients with moderate-to-severe motor symptoms had more-severe SD symptoms, and their risk of developing SD was 1.8-fold higher. There was no correlation between SD and autonomic dysfunction, sleep disturbances, or other nonmotor symptoms, and no sex difference.

Conclusions: In PD, SD is related to motor symptoms.