Condition category
Eye Diseases
Date applied
27/05/2004
Date assigned
14/07/2004
Last edited
27/04/2010
Prospective/Retrospective
Retrospectively registered
Overall trial status
Completed
Recruitment status
No longer recruiting

Plain English Summary

Not provided at time of registration

Trial website

http://www.lshtm.ac.uk/msu/opal/index.html

Contact information

Type

Scientific

Primary contact

Dr Alan Dangour

ORCID ID

Contact details

London School of Hygiene and Tropical Medicine
Keppel Street
London
WC1E 7HT
United Kingdom
+44 (0)20 7958 8133
Alan.Dangour@lshtm.ac.uk

Additional identifiers

EudraCT number

ClinicalTrials.gov number

Protocol/serial number

N/A

Study information

Scientific title

Acronym

OPAL

Study hypothesis

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.

Ethics approval

Not provided at time of registration

Study design

Randomised controlled trial

Primary study design

Interventional

Secondary study design

Randomised controlled trial

Trial setting

Not specified

Trial type

Not Specified

Patient information sheet

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

Condition

Cognitive and retinal function

Intervention

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).

Intervention type

Other

Phase

Not Specified

Drug names

Primary outcome measures

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

Secondary outcome measures

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

Overall trial start date

01/03/2004

Overall trial end date

31/03/2007

Reason abandoned

Eligibility

Participant inclusion criteria

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.

Participant type

Healthy volunteer

Age group

Senior

Gender

Not Specified

Target number of participants

800

Participant exclusion criteria

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

Recruitment start date

01/03/2004

Recruitment end date

31/03/2007

Locations

Countries of recruitment

United Kingdom

Trial participating centre

London School of Hygiene and Tropical Medicine
London
WC1E 7HT
United Kingdom

Sponsor information

Organisation

Medical Research Council (UK)

Sponsor details

Dr Ian Viney
Stephenson House
158-160 North Gower Street
London
NW1 2ND
United Kingdom
+44 (0)20 7670 4625
iv@centre-london.mrc.ac.uk

Sponsor type

Research council

Website

Funders

Funder type

Government

Funder name

UK Food Standards Agency

Alternative name(s)

Funding Body Type

Funding Body Subtype

Location

Results and Publications

Publication and dissemination plan

Not provided at time of registration

Intention to publish date

Participant level data

Not provided at time of registration

Results - basic reporting

Publication summary

1. 2006 protocol on http://www.ncbi.nlm.nih.gov/pubmed/16945130
2. 2010 results in http://www.ncbi.nlm.nih.gov/pubmed/20410089

Publication citations

  1. Protocol

    Dangour AD, Clemens F, Elbourne D, Fasey N, Fletcher AE, Hardy P, Holder GE, Huppert FA, Knight R, Letley L, Richards M, Truesdale A, Vickers M, Uauy R, 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]., Nutr J, 2006, 5, 20, doi: 10.1186/1475-2891-5-20.

  2. Results

    Dangour AD, Allen E, Elbourne D, Fasey N, Fletcher AE, Hardy P, Holder GE, Knight R, Letley L, Richards M, Uauy R, Effect of 2-y n-3 long-chain polyunsaturated fatty acid supplementation on cognitive function in older people: a randomized, double-blind, controlled trial., Am. J. Clin. Nutr., 2010, 91, 6, 1725-1732, doi: 10.3945/ajcn.2009.29121.

Additional files

Editorial Notes