Genetic variants in the apolipoprotein E (APOE) gene are associated with lipid metabolism and lipid-related traits in the non-Hispanic population. There have been limited studies regarding the association between the APOE gene and hypercholesterolemia in the Hispanic population; therefore, our aim for this study is to examine the APOE gene’s associations with cholesterol level and its related phenotypes. The APOE gene consists of three different alleles, ε2, ε3, and ε4, with ε4 being associated with dementia and cardiovascular diseases. A total of 1,382 subjects were collected from the Texas Alzheimer’s Research and Care Consortium (TARCC, N = 1320) and the Initial Study of Longevity and Dementia from the Rio Grande Valley (ISLD-RGV, N = 62). Questionnaires on demographics, medical history, and blood/saliva samples were collected and APOE genotypes were performed. We observed allele frequencies of the APOE ε3 (96.7%), ε4 (22.6%) and ε2 (6.8%) alleles, respectively. Multivariable logistic regression revealed a significant association between the APOE ε4 allele and hypercholesteremia (p = 1.8 × 10−4) in our studied Hispanic population. We prove for the first time, that the APOE ε4 allele increases the risk for hypercholesterol in Hispanics. Further research is needed to confirm and supports our current findings.

The trail making test part B (TMT-B) evaluates "executive" functions, memory, and sensorimotor functions. No previous studies were found to examine the longitudinal effect of apolipoprotein E epsilon 4 (APOE-ε4) genotypes on the TMT-B scores in Alzheimer’s disease (AD), and/or mild cognitive impairment (MCI) participants. This study used data from the Alzheimer's Disease Neuroimaging Initiative (ADNI): 482 participants with AD, 503 with cognitive normal (CN), 1,293 with MCI at baseline and follow-up of four years. The multivariable linear mixed model was used to determine the longitudinal changes in the TMT-B scores. The individuals with 1 or 2 APOE-ε4 alleles revealed significantly higher TMT-B scores (poor cognitive function) compared with individuals without APOE-ε4 allele at baseline and four follow-up visits (all p values < 0.0001). Compared with Whites, non-Hispanic African American and Hispanic populations had higher TMT-B scores (p = 0.0007 and 0.0044, respectively). Furthermore, stratified by diagnosis, the African American CN group had the highest TMT-B scores (p < 0.0001) and the Hispanic AD group had higher TMT-B scores (p = 0.0123) compared with Whites, while both African American and Hispanic MCI groups had higher TMT-B scores compared with Whites (p = 0.162 and 0.0274, respectively). In addition, stratified by racial groups, the subjects with APOE-ε4-homozgous and APOE-ε4-heterozgous showed higher TMT-B scores compared with subjects who carry zero APOE-ε4 allele just in Whites (p = 0.0023 and 0.0003, respectively); whereas there was no difference among APOE-ε4 genotypes in AA and Hispanics. In conclusion, the APOE-ε4 allele was associated with increased TMT-B scores but such associations varied by racial groups.