Dietary carotenoids reduce risk of incident Alzheimer dementia

Total carotenoid intake, particularly lutein and zeaxanthin, provides a beneficial effect on incidence of Alzheimer dementia (AD) that may be related to the inhibition of brain β-amyloid deposition and fibril formation, a study has shown.

The investigators included 927 participants from the Rush Memory and Aging Project who were free from AD at baseline and were followed for a mean of 7 years. They used Cox proportional hazards models by intakes of energy-adjusted carotenoids to estimate hazard ratios (HRs).

Brain AD neuropathology was examined in postmortem brain autopsies among 508 deceased participants. Linear regression was used to assess the association between carotenoid intake and AD-related neuropathology.

Higher consumption of total carotenoids led to a markedly lower risk of AD (top vs bottom quintile: median intake, 24.8 vs 6.7 mg/d; HR, 0.52, 95 percent confidence interval [CI], 0.33–0.81; p_trend<0.01) after controlling for age, sex, education, ApoE-ε4, participation in cognitively stimulating activities, and physical activity level.

A similar association was found for lutein-zeaxanthin, while a weaker linear inverse association existed for β-carotene. In addition, a marginally significant linear inverse association was observed for β-cryptoxanthin. In deceased participants, those with higher total carotenoids intake (top vs bottom tertile: 18.2 vs 8.2 mg/d) showed less global AD pathology (b, –0.10; SE, 0.04; p_trend=0.01).

For individual carotenoids, lutein-zeaxanthin and lycopene showed an inverse association with brain global pathology. Moreover, lutein-zeaxanthin was inversely associated with AD diagnostic score, neuritic plaque severity, and neurofibrillary tangle density and severity.