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ISRCTN
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ISRCTN72331636
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ClinicalTrials.gov identifier
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Public title
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The OPAL Study: Older People And n-3 Long-chain polyunsaturated fatty acids
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Scientific title
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Acronym
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OPAL
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Serial number at source
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N/A
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Study hypothesis
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There is considerable interest in the hypothesis that improving the diet of older people, specifically increasing the dietary intake of n-3 long-chain polyunsaturated fatty acids (n-3 LCPs) may be able to delay the initiation, or slow the progression, of cognitive decline. To date, there has been little attention given to the possible protective role of n-3 LCPs in age-related loss of cognitive or retinal function. OPAL is a double-blind randomised placebo-controlled trial carried out among adults aged 70-79 years in the UK. The intervention arm will receive a daily capsule containing 700 mg n-3 LCP (both decosahexaenoic acid DHA and eicosapentaenoic acid EPA) while the placebo arm will receive a daily capsule 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 is 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.
Study hypotheses:
1. For healthy, cognitively normal adults aged 70-79 years of age, daily supplementation with n-3 LCPs (500 mg DHA and 200 mg EPA) will slow the rate, or delay the onset, of cognitive decline.
2. For healthy, cognitively normal adults aged 70-79 years of age, daily supplementation with n-3 LCPs (500 mg DHA and 200 mg EPA) will improve visual function by enhancing rod photoreceptor response to light and visual-cortical integration.
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Lay summary
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Ethics approval
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Not provided at time of registration
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Study design
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Randomised controlled trial
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Countries of recruitment
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United Kingdom
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Disease/condition/study domain
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Cognitive and retinal function
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Participants - inclusion criteria
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Healthy volunteers aged between 70-79 years of age, who have no previous history of diabetes or dementia. Participants will be selected from 20 GP practices.
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Participants - exclusion criteria
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1. Pre-existing type I or type II diabetes at baseline
2. Pre-existing dementia at baseline
3. Reported daily use of fish-oil supplements (in liquid or capsule form) at baseline
4. Mini-mental state examination (MMSE) score <24 at baseline screen
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Anticipated start date
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01/03/2004
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Anticipated end date
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31/03/2007
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Status of trial
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Completed |
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Patient information material
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Patient information on the various different aspects of the trial can be found on the website at: http://www.lshtm.ac.uk/msu/opal/information.html
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Target number of participants
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800
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Interventions
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Daily nutritional supplement of 0.7 g of n-3 long chain polyunsaturated fatty acids (fish oil) versus placebo.
The main outcome variable assessed at 24 months will be cognitive performance and a second major outcome variable will be retinal function (Moorfields Eye Hospital will undertake retinal testing in a sub group).
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Primary outcome measure(s)
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1. Change in cognitive function at 24 months determined by the California Verbal Learning Test
2. Change in rod sensitivity over 24 months of intervention as measured by electroretinogram
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Secondary outcome measure(s)
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1. Cognitive performance as measured by immediate and delayed recall of a short story, tests of prospective memory, timed letter search/cancellation task, verbal fluency, digit span backwards, symbol digit modalities test, simple and choice reaction time, dual-task performance and spatial memory
2. Blood pressure
3. Measure of depression
4. Change in Body Mass Index
5. Compliance determined by counting the number of tablets remaining every 3 months, and by measuring the change in n-3 LCP concentration in buccal epithelial cells over 24 months
6. Number of hospital admissions for cardiovascular events over 24 months
7. Death
8. Colour vision measured by detecting sensitivity to colour contrast which is a good marker of central retinal function
9. Eye health assessed by carrying out a full ophthalmic examination
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Sources of funding
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UK Food Standards Agency
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Trial website
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http://www.lshtm.ac.uk/msu/opal/index.html
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Publications
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1. 2006 protocol on http://www.ncbi.nlm.nih.gov/pubmed/16945130
2. 2010 results in http://www.ncbi.nlm.nih.gov/pubmed/20410089
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Contact name
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Dr
Alan
Dangour
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Address
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London School of Hygiene and Tropical Medicine
Keppel Street
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City/town
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London
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Zip/Postcode
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WC1E 7HT
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Country
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United Kingdom
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Tel
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+44 (0)20 7958 8133
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Fax
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+44 (0)20 7958 8111
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Email
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Alan.Dangour@lshtm.ac.uk
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Sponsor
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Medical Research Council (UK)
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Address
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Dr Ian Viney
Stephenson House
158-160 North Gower Street
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City/town
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London
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Zip/Postcode
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NW1 2ND
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Country
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United Kingdom
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Tel
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+44 (0)20 7670 4625
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Fax
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+44 (0)20 7670 4890
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Email
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iv@centre-london.mrc.ac.uk
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Date applied
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27/05/2004
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Last edited
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27/04/2010
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Date ISRCTN assigned
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14/07/2004
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