APOE and Cognitive impairment: Several studies have shown that the APOE4 allele increases the risk of progression of cognitive impairment to Alzheimer’s-type dementia more than fourfold (p < 0.001), and it is known that the APOE4 allele is associated with both bone loss and cognitive impairment (Macdonald et al., 2008; Zachara et al., 2022), so we can infer that the association between reduced bone mineral density and association between reduced BMD and reduced cognitive function may result from the action of the APOE4 allele.