Figure 1.

Schematic illustration and graphs constructed by plotting the number of papers published per year in indexed journals listed on the PubMed platform. The arrows indicate the multifactorial and interactive connections, including inflammation, oxidative stress, hypertension and angiotensin/ACE2. We interpreted the sharp increase in the number of published papers relating to angiotensin/ACE2 in 2020 as being due to its role in COVID-19. The bottom panel shows a large jump in the number of papers in “microbiota” (~26,000), demonstrating the current relevance of therapies based on the use of probiotics and that kefir shows a similar profile. ACE2: Angiotensin-Converting Enzyme type 2. The above diagram was created by one of the coauthors of this review, a 76-year-old researcher suffering from PD for 12 years.