In agreement to this, recent studies have strengthened the hypothesis that PD is a risk factor for RA development: correlates show that greater severity of RA (swollen joints), increased erythrocyte sedimentation rate (ESR) and CRP typical of RA, can be associated with severe instances of periodontal bone resorption (de Molon et al., 2019; Bartold and Lopez-Oliva, 2020). Here, CRP is linked to Parkinson disease.