Effects of APOE ɛ4 on brain amyloid, lacunar infarcts, and white matter lesions: a study among patients with subcortical vascular cognitive impairment

The relationship between the apolipoprotein E ɛ4 allele (APOE4) and factors associated with vascular cognitive impairment (VCI) is unclear. We aimed to examine the effects of APOE4 on brain amyloid beta using Pittsburg compound B (PiB) and subcortical cerebrovascular disease, as assessed by lacunes and white matter hyperintensities (WMH) in subcortical VCI (SVCI) patients. We recruited 230 subjects with normal cognition, 111 subjects with cognitive impairment due to clinically defined Alzheimer's disease (ADCI), and 134 subjects with clinically defined SVCI. A PiB retention ratio greater than 1.5 was considered to be PiB positive. Logistic regression analysis was performed to investigate whether APOE4 increased the risk for each cognitive impairment group. Multiple linear regression analysis was performed to investigate whether APOE4 was associated with brain amyloid beta, lacunes, and WMH. APOE4 did not increase the risk of PiB(−) SVCI (odds ratio [OR], 1.50; 95% confidence interval [CI], 0.79-2.84), whereas APOE4 increased the risk of PiB(+) SVCI (OR, 4.52; 95% CI, 1.70-11.97) and PiB(+) ADCI (odds ratio, 4.84; 95% CI, 2.54-7.91). In SVCI patients, APOE4 was positively associated with PiB retention ratio, whereas APOE4 was not associated with the number of lacunes or with WMH volume. Our results suggest that amyloid beta burden can occur in patients with and without subcortical cerebrovascular disease, and that it is associated with APOE4. However APOE4 might be independent of subcortical cerebrovascular disease.