There is evidence to support this within the literature, with studies reporting no association between risk factors (vitamin-B-12, smoking, physical fitness) and dementia (Crystal et al., 1994; Piguet et al., 2003; Verghese et al., 2003; Wang et al., 1999), or at least a declining strength of association (APOE ε4; Corrada, Paganini-Hill, Berlau, & Kawas, 2013; Farrer et al., 1997). The gene discussed is APOE; the disease is dementia.