Participants with dementia and/or MCI were older (p < 0.001), had less teeth (p = 0.010), higher serum levels of IL-8 (p = 0.047) and TGF-β (p = 0.022), a higher waist to hip ratio (p = 0.019), attained worse scores in MMSE (p < 0.001), BADLS (p < 0.001) and GDS (p < 0.001), were more likely to carry a greater number of APOE ε4 risk alleles (p < 0.001), have hypertension (p = 0.002), be educated to a lower level (p < 0.001) and be within a lower social class (p = 0.002), compared to participants without dementia and/or MCI. The gene discussed is APOE; the disease is hypertensive disorder.