Association Between APOE Alleles and Change of Neuropsychological Tests in the Long Life Family Study

Abstract

Background:

The Long Life Family Study (LLFS) is a family based, prospective study of healthy aging and familial longevity. The study includes two assessments of cognitive function that were administered approximately 8 years apart.

Objective:

To test whether APOE genotype is associated with change of cognitive function in older adults.

Methods:

We used Bayesian hierarchical models to test the association between APOE alleles and change of cognitive function. Six longitudinally collected neuropsychological test scores were modelled as a function of age at enrollment, follow-up time, gender, education, field center, birth cohort indicator (≤1935, or >1935), and the number of copies of ɛ2 or ɛ4 alleles.

Results:

Out of 4,587 eligible participants, 2,064 were male (45.0%), and age at enrollment ranged from 25 to 110 years, with mean of 70.85 years (SD: 15.75). We detected a significant cross-sectional effect of the APOE ɛ4 allele on Logical Memory. Participants carrying at least one copy of the ɛ4 allele had lower scores in both immediate (–0.31 points, 95% CI: –0.57, –0.05) and delayed (–0.37 points, 95% CI: –0.64, –0.10) recall comparing to non-ɛ4 allele carriers. We did not detect any significant longitudinal effect of the ɛ4 allele. There was no cross-sectional or longitudinal effect of the ɛ2 allele.

Conclusion:

The APOE ɛ4 allele was identified as a risk factor for poorer episodic memory in older adults, while the APOE ɛ2 allele was not significantly associated with any of the cognitive test scores.