Apolipoprotein E phenotypes in demented and cognitively impaired patients with and without cerebrovascular disease

Controversy exists regarding the apolipoprotein E (ApoE) ɛ4 allele association with vascular dementia (VaD), ranging from increased ɛ4 frequency, similar to that found for Alzheimer's disease (AD), to no association between the ɛ4 allele and VaD. To clarify further the relationship between ApoE alleles polymorphism and cerebrovascular disease (CVD) in demented and cognitively impaired patients, we examined the ApoE phenotypes in a sample of 280 patients: 155 with AD, 21 with VaD, 32 with mixed dementia (MD), 45 with mild cognitive impairment (MCI) but without CVD, and 27 in which vascular disease was the most probable cause of cognitive decline [vascular mild cognitive impairment (VMCI)]. Our results show that the frequency of the ApoE ɛ4 allele in patients over 70 years old with clinically diagnosed VaD and VMCI does not differ significantly from that of controls. In contrast, ApoE ɛ4 allele-bearing individuals had greater risk of having late-onset AD (OR=8.8; 95% Cl 3.7–21.0), or non-vascular cognitive impairment (OR=7.0; 95% Cl 2.5–19.0).