Nutritional Strategies in the Management of Alzheimer Disease: Systematic Review With Network Meta-Analysis

Alzheimer disease (AD) is the major cause of dependency and disability in the elderly. Numerous studies have sought to achieve its prevention and/or management examining a role for modifiable risk factors, such as nutrition. This work aims to investigate the effects of food and/or nutrients in the management of AD at different stages.

Electronic databases were searched for clinical trials examining the effect of nutrient intervention in individuals with AD, compared with placebo, published up to 2014. The outcomes investigated were neuropsychological assessment scales, neuroimaging, and biomarkers. The Cochrane tool was employed to assess risk of bias. Pairwise meta-analyses were performed in a random-effect model by estimating the weighted mean differences with 95% confidence interval (CI) for each outcome measure. The Network meta-analysis was undertaken on cognitive outcome.

Selected studies used antioxidants, B-vitamins, inositol, medium-chain triglyceride, omega-3, polymeric formulas, polypeptide, and vitamin D. AD outcome measurements were mainly restricted to cognitive state and functional abilities. Estimate treatment effects from pairwise meta-analyses showed large but nonsignificant effect in the supplementation with proline-rich polypeptide [weighted mean difference 6.93 (95% CI -3.04, 16.89); P = .17] and B-vitamins [weighted mean difference 0.52 (95% CI -0.05, 1.09); P = .07) on cognitive function measured by the Mini-Mental State Examination. The other nutrients supplementation did not show any significant effect on any outcome measures.

Isolated nutrient supplementations show no convincing evidence of providing a significant benefit on clinical manifestations or neuropathology of AD. During the initial stages of AD, nutrient supplementation did not show any effect when delivered individually, probably because of their synergistic function on brain, at different domains.