Beta-carotene, telomerase activity and Alzheimer’s disease in old age subjects

Purpose: Advancing age represents the strongest risk factor for Alzheimer’s disease (AD), and the identification of biomarkers able to define what characterizes physiological aging from AD may represent a potential starting point for novel preventive strategies. Among these biomarkers, telomeres seem to be a promising target. Interestingly, high intake of carotenoid-rich food may play a role in protecting telomeres by oxidative stress reduction. Accordingly, low plasma β-carotene concentrations have been found in AD subjects when compared with cognitively healthy subjects. In this study, we aim at investigating the hypothesis that low β-carotene might be associated with markers of accelerated cellular aging, including leucocyte telomere length (LTL) and peripheral mononuclear cell (PBMC) telomerase activity in a cohort of old age subjects. Methods: The study was conducted in 68 old age subjects, 37 AD, and 31 age-matched healthy controls. In all subjects, β-carotene plasma level, LTL and peripheral telomerase activity were measured. Results: In all populations, β-carotene significantly and positively (r = 0.320, p = 0.008) correlated with telomerase activity, independent of gender. A model having telomerase activity levels as the dependent variable, and age, gender, smoking habit, and β-carotene as independent variables, confirmed that β-carotene was independently associated with telomerase activity (β = 0.319, p = 0.012). Subjects affected by AD had significantly lower plasmatic levels of β-carotene (448 ± 66 mg/ml vs 497 ± 59 mg/ml, p = 0.001) and LTL (0.53 ± 0.25 vs 0.69 ± 0.29; p = 0.009) as compared with healthy controls. Β-carotene plasma level was associated with AD diagnosis (OR 0.988; IC95% 0.978–0.997; p = 0.013) independently of age, gender, smoking habit, ApoE genotype, and LTL. Conclusion: Our data show that β-carotene may modulate telomerase activity in old age. Moreover, lower plasma β-carotene levels, correlating with peripheral telomerase activity, are associated with AD diagnosis independent of multiple covariates.