OPAL Protocol
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.