In the CSF of middle-aged adults (average age 54.5 years) with no dementia, apoE particles were smaller in both ε3/ε4 and ε4/ε4 individuals than in ε3/ε3 individuals, but larger in ε2/ε3 individuals (Heinsinger et al., 2016; Nelson and Sen, 2019). This evidence concerns the gene APOE and dementia.