Key result
APOE-ε4 alleles were associated with higher TMT-B scores in White subjects compared to those without the allele, but no differences were found in Hispanic and African American groups over 4 years.
Why the study?
No previous study had examined the longitudinal effect of APOE-ε4 genotypes on Trail Making Test part B scores across racial groups in Alzheimer's disease.
Does the APOE-ε4 genotype affect TMT-B scores differently across racial groups in patients with Alzheimer's disease and cognitive impairment?
Cohort (n=2,178)
Does the APOE-ε4 genotype affect TMT-B scores differently across racial groups in patients with Alzheimer's disease and cognitive impairment?
The APOE-ε4 allele is associated with worse executive function and memory (higher TMT-B scores) in White individuals, but not in Hispanic or African American individuals.
APOE-ε4 was associated with worse TMT-B only in Whites; leaves open ancestry-specific genetic effects on executive function in AD.
OBJECTIVES: The trail making test part B (TMT-B) evaluates executive functions, memory, and sensorimotor functions. No previous study was found to examine the longitudinal effect of APOE-ε4 genotypes on the TMT-B scores in Alzheimer's disease (AD) across racial groups. METHODS: This study used the data from Alzheimer's Disease Neuroimaging Initiative (ADNI): 382 participants with AD, 503 with cognitive normal (CN), 1293 with mild cognitive impairment (MCI) at baseline and follow-up of four years. The multivariable linear mixed model was used to investigate the effect of APOE-ε4 genotypes on changes in TMT-B scores. RESULTS: Compared with Whites, African Americans (AA) and Hispanics had higher TMT-B scores (poor cognitive function). Furthermore, Whites subjects with 1 or 2 APOE-ε4 alleles had significantly higher TMT-B scores compared with individuals without APOE-ε4 allele at baseline and four follow-up visits; however, no differences in TMT-B were found between APOE-ε4 alleles in the Hispanic and AA groups. No APOE-ε4 by visit interactions was found for 3 racial groups. Stratified by AD diagnosis, the APOE-ε4 allele was associated with TMT-B scores only in the MCI group, while there were significant interactions for visit by education, APOE-ε4 allele, and the Mini Mental State Examination (MMSE) score in the MCI group. In addition, TMT-B was significantly correlated with the MMSE, AD Assessment Scale-cognitive subscale 13 (ADAS13), tTau, pTau, Aβ42, and hippocampus. CONCLUSIONS: APOE-ɛ4 allele is associated with TMT-B scores in Whites subjects, but not in the Hispanic and AA groups. APOE-ε4 showed interaction with visit in the MCI group.
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Xu et al. (2023) conducted a cohort in Alzheimer's disease and mild cognitive impairment (n=2,178). APOE-ε4 genotype vs. No APOE-ε4 allele was evaluated on Changes in TMT-B scores. APOE-ε4 alleles were associated with higher TMT-B scores in White subjects compared to those without the allele, but no differences were found in Hispanic and African American groups over 4 years.
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