Apolipoprotein E ε4-dependent associations between carotenoids and cognitive decline: Findings from the MIND (Mediterranean-DASH Intervention for Neurodegenerative delay) randomized controlled trial.

BACKGROUND

Alzheimer disease (AD) prevention is a public health priority, yet the impact of dietary carotenoids on cognitive decline, particularly in apolipoprotein E (APOE) ε4 carriers, remains unclear.

OBJECTIVES

The objective of this study was to examine whether the APOE ε4 genotype modifies the relationship between blood carotenoid concentrations and global cognition.

METHODS

This study was conducted within the Mediterranean-Dietary Approaches to Stop Hypertension intervention for neurodegenerative delay trial, a 3-y randomized controlled trial comparing the effects of the Mediterranean-Dietary Approaches to Stop Hypertension intervention for neurodegenerative delay diet with the usual diet on global cognition in older adults. Eligible participants were ≥65 y, had a body mass index (in kg/m2) >25, a family history of AD, suboptimal diets, and a Montreal cognitive assessment score ≥22. The primary outcome was 3-y change in global cognitive function, assessed using a validated composite cognitive score converted to standardized units (SUs). Baseline plasma carotenoid concentrations were measured in a subgroup of participants (n = 442). Mixed-effects models were used to test the interaction between APOE ε4 status and baseline carotenoid concentrations on cognitive trajectories.

RESULTS

The mean age was 70.0 y for noncarriers (n = 308) and 69.4 y for APOE ε4 carriers (n = 134). Among APOE ε4 carriers, a 1-unit increment in plasma total carotenoids at baseline was associated with higher global cognitive scores [β = 0.17 SU; 95% confidence interval (CI): 0.06, 0.28 SU; P = 0.009]. Similar associations were observed for β-carotene (β = 0.13 SU; 95% CI: 0.05, 0.21 SU; P = 0.001), α-carotene (β = 0.09 SU; 95% CI: 0.02, 0.15 SU; P = 0.008), lutein plus zeaxanthin (β = 0.14 SU; 95% CI: 0.04, 0.25 SU; P = 0.008), lycopene (β = 0.17 SU; 95% CI: 0.07, 0.28 SU; P = 0.005), and β-cryptoxanthin (β = 0.13 SU; 95% CI: 0.05, 0.21 SU; P = 0.03). Associations in noncarriers were weaker or nonsignificant.

CONCLUSIONS

Higher plasma carotenoid concentrations were associated with slower cognitive decline in APOE ε4 carriers, potentially mitigating genetic risk. This trial was registered at clinicaltrials.gov as NCT02817074.