APOE and Visual impairment: These were three gut microbiome molecules (5OH-IAA, IBA, 2-methylbutyric acid) and 13 covariates (age, sex, homozygous APOE-ɛ4 vs none, heterozygous APOE-ɛ4 vs. none, MMSE score, family history of dementia, physical active vs. inactive, prevalent visual impairment, prevalent stroke, history of TBI, medication, serotonin, and study center Düsseldorf vs. Bonn).