Abstract
The number of individuals with age-related cognitive impairment is rising dramatically in the UK and globally. There is considerable interest in the general hypothesis that improving the diet of older people may slow the progression of cognitive decline. To date, there has been little attention given to the possible protective role of n-3 long-chain polyunsaturated fatty acids (n-3 LCPs) most commonly found in oily fish, in age-related loss of cognitive function. The main research hypothesis of this study is that an increased dietary intake of n-3 LCPs will have a positive effect on cognitive performance in older people in the UK.To test this hypothesis, a double-blind randomised placebo-controlled trial will be carried out among adults aged 70–79 years in which the intervention arm will receive daily capsules containing n-3 LCP (0.5 g/day docosahexaenoic acid and 0.2 g/day eicosapentaenoic acid) while the placebo arm will receive daily capsules containing olive oil. The main outcome variable assessed at 24 months will be cognitive performance and a second major outcome variable will be retinal function. Retinal function tests are included as the retina is a specifically differentiated neural tissue and therefore represents an accessible window into the functioning of the brain.The overall purpose of this public-health research is to help define a simple and effective dietary intervention aimed at maintaining cognitive and retinal function in later life. This will be the first trial of its kind aiming to slow the decline of cognitive and retinal function in older people by increasing daily dietary intake of n-3 LCPs. The link between cognitive ability, visual function and quality of life among older people suggests that this novel line of research may have considerable public health importance.
Highlights
Background and rationaleThe number of individuals with age-related cognitive impairment is rising dramatically in the UK [1] and globally [2]
In line with previous studies on the effect of docosahexaenoic acid (DHA) during infant development, we anticipate that an increase in dietary intake of DHA will significantly improve rod sensitivity; increases of the order of +2SD in rod sensitivity have been demonstrated in studies of DHA supplementation in preterm infants [23,24]
The number of individuals with age-related cognitive impairment is rising worldwide, and public health interventions aimed at slowing this rise are urgently needed
Summary
The number of individuals with age-related cognitive impairment is rising dramatically in the UK [1] and globally [2]. Age-related decrease in n-3 LCP level in total brain lipids have been reported in humans, and it has been postulated that this decline is correlated in part with age-related deterioration of functions of the central nervous system [5,6] This findings may be relevant in the UK since recent survey data [7] demonstrates that older people in the UK habitually consume a diet that is low in fish. It is hypothesised that increasing dietary DHA intake among older people will result in increased levels of DHA in the brain and retina, and enhance phototransduction efficiency and light sensitivity. Improving the quality of life and independence of older people, may help to reduce the number of disability-adjusted life-years lost through poor cognitive and retinal function in the UK
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