Periodontitis is characterised as a low-grade systemic disease with the presence of gingival oedema, congestion, erythema, periodontal pockets, and loss of bone and soft tissue supporting the teeth,29,30 as well as release of pro-inflammatory cytokines into the systemic circulation, and an increase of C-reactive protein (CRP).11 PD is known to have multiple microbial aetiologies, and patients who eventually develop sporadic AD tend to have recurrent infections before clinical diagnosis of dementia. Here, CRP is linked to dementia.