Age and socioeconomic status (household income and education level), smoking status, AD status, self-reported DM status, HOMA-IR and HbA1c, blood pressure (SBP and DBP), heart rate, total white cell and neutrophils counts, Vitamin D levels as well as CRP levels, were significantly associated with one or more of the skin physiology parameters (Fig. 2; Supplementary Table 5). Here, CRP is linked to Alzheimer disease.