Plain language summary
The prevalence of neurodegenerative disorders (ND) and age-related macular degeneration (AMD) is increasing among the elderly population. Oxidative stress and inflammation play a role in both diseases, and recent evidence has shown that walnuts, rich in omega-3 fatty acids, have potential to beneficially impact neuronal function in both the brain and retina. The aim of the Walnuts and Healthy Aging (WAHA) study is to provide an initial protocol for investigating the effects of walnut consumption on cognitive and retinal health among healthy elderly participants. The study will be conducted for two years and participants will be randomised to the placebo group or to consume walnuts daily for two years. This study expects that regular walnut consumption will have beneficial effects for delaying the onset of age-related cognitive impairment and retinal pathology.
Abstract
Introduction: An unwanted consequence of population aging is the growing number of elderly at risk of neurodegenerative disorders, including dementia and macular degeneration. As nutritional and behavioral changes can delay disease progression, we designed the Walnuts and Healthy Aging (WAHA) study, a two-center, randomized, 2-year clinical trial conducted in free-living, cognitively healthy elderly men and women. Our interest in exploring the role of walnuts in maintaining cognitive and retinal health is based on extensive evidence supporting their cardio-protective and vascular health effects, which are linked to bioactive components, such as n-3 fatty acids and polyphenols. Methods: The primary aim of WAHA is to examine the effects of ingesting walnuts daily for 2 years on cognitive function and retinal health, assessed with a battery of neuropsychological tests and optical coherence tomography, respectively. All participants followed their habitual diet, adding walnuts at 15% of energy (≈30-60 g/day) (walnut group) or abstaining from walnuts (control group). Secondary outcomes include changes in adiposity, blood pressure, and serum and urinary biomarkers in all participants and brain magnetic resonance imaging in a subset. Results: From May 2012 to May 2014, 708 participants (mean age 69 years, 68% women) were randomized. The study ended in May 2016 with a 90% retention rate. Discussion: The results of WAHA might provide high-level evidence of the benefit of regular walnut consumption in delaying the onset of age-related cognitive impairment and retinal pathology. The findings should translate into public health policy and sound recommendations to the general population (ClinicalTrials.gov identifier NCT01634841).
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