A positive association between BB-DNA and plasma BDNF levels was found in the whole AD group (β coefficient = 0.239 and p < 0.05, Table S1A; β coefficient = 0.231 and p < 0.05, Table S1B, Supplementary Materials) and in AD patients with CDR2 (β coefficient = 0.407 and p < 0.05) (Table 2). The gene discussed is BDNF; the disease is Alzheimer disease.