Risk Factors Predicting Amyloid PET Positivity in Patients with Mild Cognitive Impairment and Apolipoprotein E ε3/ε3 Genotypes

Background: The apolipoprotein E (APOE) epsilon 4 allele is a well-known risk factor for AD and is associated with higher amyloid deposition and earlier dementia onset. However, the relationship between amyloid pathology and the most common APOE allele, epsilon 3, has not been well studied. Objective: In this study, we aimed to identify the risk factors predicting amyloid PET positivity in patients with mild cognitive impairment (MCI) and APOE epsilon 3/epsilon 3 genotypes. Methods: We retrospectively reviewed the medical records of MCI patients with APOE epsilon 3/epsilon 3 genotypes who underwent amyloid PET scanning. Demographics, neuropsychological tests, and brain MRI were obtained. We analyzed which risk factors could affect amyloid PET positivity in MCI patients with APOE epsilon 3/epsilon 3 genotypes using logistic regression models. Results: We recruited 171 MCI patients with APOE epsilon 3/epsilon 3 genotypes in this study. Out of 171 patients, 49 patients (28.65%) showed positive results in the amyloid PET scans. In a multivariate logistic regression model, amyloid positivitywas associated with frontal atrophy (OR = 2.63, p = 0.009), and CDR-SOB scores (OR = 2.46, p = 0.013). The odds ratio for amyloid PET positivity in patients older than and equal to 75 years with both frontal atrophy and CDR-SOB scores >1.0 was 3.63. Conclusion: Our study demonstrated that frontal atrophy, high CDR-SOB scores, and old age were risk factors associated with amyloid PET positivity in MCI with APOE epsilon 3/epsilon 3 genotypes.