Although the study analysis was only performed on one twin pair, who share nearly 100% of their genes, we found remarkable differences in lifestyle factors during their lifespan (e.g., lack of regular exercise, coffee consumption, and heavy smoking), blood neurodegenerative and vascular biomarkers (especially in case of αSyn, as well as MMP-2, MB, Apo-A1, Apo-CIII, Apo-H levels), neuropsychological tests (ACE, MoCA, MMSE), and brain MRI findings (cerebellar lacunar stroke, midbrain atrophy, signs of NPH, WMH lesions and brain volume changes) in the affected twin. This evidence concerns the gene APOC3 and normal pressure hydrocephalus.