Seasonality as a risk factor for deaths in Parkinson's disease

According to growing evidence, sleep disruption harms biological processes and circadian homeostasis. Diurnal motor symptom volatility in Parkinson's Disease (PD) has been extensively studied. Few studies examined seasonal variability in PD symptoms, some showing it and others not.

To investigate whether PD patients' deaths follow a rhythmic pattern due to circadian rhythm alterations.

This study used only unidentified patient databases. People with PD, ICD10 code G20, in at least one death certificate field were selected. The Continuous Wavelet Transform and Fourier Transform were checked for oscillation and its duration.

The 18-year analysis found 43,072 PD deaths. The Continuous Wavelet transform revealed a 351.87-day annual component (p < 0.05). Winter in the southern hemisphere saw more deaths, mainly in July. The Continuous Wavelet transform identified a significant daily component (p < 0.05) of 22.81 hours. Fatalities peaked around 9 a.m. Pneumonia is the leading cause of death in PD, and women and men have the same rhythm pattern.

Parkinson's disease mortality in Brazil follows a pattern. Using over 40.000 death certificates from 18 years, the authors found that Parkinson's patient fatalities rise in winter and peak in July at about 9 a.m. Sunlight reduction increases mortality risk in the long term. Low sunshine lowers temperatures, increasing short-term death risk. This is crucial because it prioritizes the sun, seasons, and circadian rhythm over low temperatures.