Headache and rhinitis: pattern search on Google Trends for 17 years.

Objective: Headache and rhinitis are highly prevalent and comorbid. The objective of the present study is to analyze the correlation of headache and rhinitis, in addition to the temporal pattern of these diseases in 17 years, using the Google Trends platform.
Methods: Google Trends was searched from January 2004 to June 2021, using the entry: ["rinite" (rhinitis) + "dor de cabeça" (headache)" + "Alzheimer" + "enxaqueca" (migraine)]. Migraine, primary headache, and Alzheimer's, with no clear relation with headache, were used as controls. After the descriptive analysis by dispersion diagrams, Pearson's test and a simple regression model were performed. Subsequently, this study analyzed the seasonality of the volume of research on rhinitis and headache.
Results: A strong correlation between rhinitis and headache (0.86) was found in the time interval analyzed. In addition, a seasonality was identified in the volume of searches for the term rhinitis with increased volume in the fall and peaks in the month of May, with a decrease in the spring and early summer. Moreover, an increase of searches on headache was observed, suggesting worse burden of this pathology.
Conclusion: Headaches and rhinitis were correlated in 17 years of research on the Google Trends platform. Circannual variation of both conditions was observed. Additional studies with digital research may be useful to better understand the epidemiology and comorbidities of headache.