A randomised controlled trial investigating the effect of n-3 long-chain polyunsaturated fatty acid supplementation on cognitive and retinal function in cognitively healthy older people: the Older People And n-3 Long-chain polyunsaturated fatty acids (OPAL) study protocol [ISRCTN72331636]

Alan D Dangour, Felicity Clemens, Diana Elbourne, Nicky Fasey, Astrid E Fletcher, Pollyanna Hardy, Graham E Holder, Felicia A Huppert, Rosemary Knight, Louise Letley, Marcus Richards, Ann Truesdale, Madge Vickers, Ricardo Uauy, Alan D Dangour, Felicity Clemens, Diana Elbourne, Nicky Fasey, Astrid E Fletcher, Pollyanna Hardy, Graham E Holder, Felicia A Huppert, Rosemary Knight, Louise Letley, Marcus Richards, Ann Truesdale, Madge Vickers, Ricardo Uauy

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.

Figures

Figure 1
Figure 1
Flow-chart of cognitive function study protocol.
Figure 2
Figure 2
Flow-chart of retinal function study protocol.

References

    1. Melzer D, Ely M, Brayne C. Cognitive impairment in elderly people: population based estimate of the future in England, Scotland, and Wales. Bmj. 1997;315:462.
    1. Ferri CP, Prince M, Brayne C, Brodaty H, Fratiglioni L, Ganguli M, Hall K, Hasegawa K, Hendrie H, Huang Y, Jorm A, Mathers C, Menezes PR, Rimmer E, Scazufca M. Global prevalence of dementia: a Delphi consensus study. Lancet. 2005;366:2112–2117. doi: 10.1016/S0140-6736(05)67889-0.
    1. WHO/TUFTS . Keep fit for life: meeting the nutritional needs of older persons. Geneva , World Health Organisation; 2002.
    1. Uauy R, Hoffman DR, Peirano P, Birch DG, Birch EE. Essential fatty acids in visual and brain development. Lipids. 2001;36:885–895.
    1. Soderberg M, Edlund C, Kristensson K, Dallner G. Lipid compositions of different regions of the human brain during aging. J Neurochem. 1990;54:415–423.
    1. Soderberg M, Edlund C, Kristensson K, Dallner G. Fatty acid composition of brain phospholipids in aging and in Alzheimer's disease. Lipids. 1991;26:421–425.
    1. Finch S, Doyle W, Lowe C, al. National diet and nutrition study - people aged 65 years and over. London , HMSO; 1998.
    1. Kalmijn S, van Boxtel MP, Ocke M, Verschuren WM, Kromhout D, Launer LJ. Dietary intake of fatty acids and fish in relation to cognitive performance at middle age. Neurology. 2004;62:275–280.
    1. Barberger-Gateau P, Letenneur L, Deschamps V, Peres K, Dartigues JF, Renaud S. Fish, meat, and risk of dementia: cohort study. Bmj. 2002;325:932–933. doi: 10.1136/bmj.325.7370.932.
    1. Kalmijn S, Feskens EJ, Launer LJ, Kromhout D. Polyunsaturated fatty acids, antioxidants, and cognitive function in very old men. Am J Epidemiol. 1997;145:33–41.
    1. Morris MC, Evans DA, Bienias JL, Tangney CC, Bennett DA, Wilson RS, Aggarwal N, Schneider J. Consumption of fish and n-3 fatty acids and risk of incident Alzheimer disease. Arch Neurol. 2003;60:940–946. doi: 10.1001/archneur.60.7.940.
    1. Whalley LJ, Fox HC, Wahle KW, Starr JM, Deary IJ. Cognitive aging, childhood intelligence, and the use of food supplements: possible involvement of n-3 fatty acids. Am J Clin Nutr. 2004;80:1650–1657.
    1. Rojas CV, Martinez JI, Flores I, Hoffman DR, Uauy R. Gene expression analysis in human fetal retinal explants treated with docosahexaenoic acid. Invest Ophthalmol Vis Sci. 2003;44:3170–3177. doi: 10.1167/iovs.02-1138.
    1. Birch DG, Hood DC, Locke KG, Hoffman DR, Tzekov RT. Quantitative electroretinogram measures of phototransduction in cone and rod photoreceptors: normal aging, progression with disease, and test-retest variability. Arch Ophthalmol. 2002;120:1045–1051.
    1. Lim W, Gammack J, Van Niekerk J, Dangour A. Omega 3 fatty acid for the prevention of dementia. Cochrane Database Syst Rev. 2006:CD005379.
    1. Folstein MF, Folstein SE, McHugh PR. "Mini-mental state". A practical method for grading the cognitive state of patients for the clinician. J Psychiatr Res. 1975;12:189–198. doi: 10.1016/0022-3956(75)90026-6.
    1. The OPAL study []
    1. Norman MA, Evans JD, Miller WS, Heaton RK. Demographically corrected norms for the California Verbal Learning Test. J Clin Exp Neuropsychol. 2000;22:80–94.
    1. Goldberg DP. The detection of psychiatric illness by questionnaire. London , Oxford University Press; 1972.
    1. Department of Education and Science . Burnham Further Education Committee Grading Courses. London , HMSO; 1972.
    1. Scientific Advisory Committee on Nutrition . Advice on fish consumption: benefits and risks. London , The Stationary Office; 2004.
    1. Kris-Etherton PM, Harris WS, Appel LJ. Fish consumption, fish oil, omega-3 fatty acids, and cardiovascular disease. Circulation. 2002;106:2747–2757. doi: 10.1161/01.CIR.0000038493.65177.94.
    1. Birch EE, Birch DG, Hoffman DR, Uauy R. Dietary essential fatty acid supply and visual acuity development. Invest Ophthalmol Vis Sci. 1992;33:3242–3253.
    1. Uauy RD, Birch DG, Birch EE, Tyson JE, Hoffman DR. Effect of dietary omega-3 fatty acids on retinal function of very-low-birth-weight neonates. Pediatr Res. 1990;28:485–492.
    1. Marmor MF, Holder GE, Seeliger MW, Yamamoto S. Standard for clinical electroretinography (2004 update) Doc Ophthalmol. 2004;108:107–114. doi: 10.1023/B:DOOP.0000036793.44912.45.

Source: PubMed

Sponsorer og samarbejdspartnere

Medicinske tilstande

Narkotikainterventioner

3
Abonner