Omega-3 fatty acids are essential
fatty acids that play a crucial role in brain function and visual acuity.
Unfortunately, the body can't make them. They have to be derived from the food
such as fatty fish (salmon, tuna, etc.), seafood including algae and krill,
flaxseed, soy and nut oils.
Although Omega-3 fatty acids have
become popular because they may reduce heart disease, a number of studies have
found increased dietary consumption of
omega-3 (n-3) fatty acid - DHA (docosahexaenoic acid) to be useful in
protecting against cognitive decline, including Alzheimer's disease and
dementia, in elderly people.
However, the results of the
studies are not entirely consistent. So far only two randomized, controlled
trials have assessed the effect of n-3 LC PUFA supplementation on the cognitive
function in the older population. Out of this only one study could establish a
link between omega-3 long-chain polyunsaturated fatty acids and cognitive
decline. According to the 2005 study published in the Archives of Neurology
'there was little evidence that the omega-3 polyunsaturated fatty acids were
associated with cognitive change'. But they concluded that 'fish consumption
may be associated with slower cognitive decline with age'. They recommended
further studies to determine 'whether fat composition is the relevant dietary
constituent'. On the other hand, a Canadian study published in the Journal of
Alzheimer's disease did not support the hypothesis that n-3 LC PUFAs (omega-3
long chain polyunsaturated fatty acids) play a protective role in cognitive
function and dementiadespite
adjusting the results for age, sex, education, smoking, alcohol intake, BMI,
history of cardiovascular disease and most importantly apolipoprotein E
epsilon4 (APOE epsilon4) gene.
The difference in results may be
because of the differences in design and methods of studies, but scientists are
finding evidence that the genetic make-up (especially the effect of the gene
APOE epsilon4) and physiological wellbeing of the subjects also significantly
influence the study outcome.
Thus, the benefits of n-3 LC PUFA
supplementation on cognitive function in older normal people still remains
unclear. So, a controlled trial to investigate the potential of n-3 LC PUFA,
with special focus on APOE epsilon4 gene, as moderating factor to slow
cognitive decline in cognitively healthy older adults has been undertaken by
Vanessa Danthiir and her colleagues from Australia. The researchers
hypothesized that 'over 18 months, the n-3 LC PUFA supplementation group would
show slower cognitive decline than the control group'. This methodology study
paper has been published in the Nutrition Journal.
The study dose was 1720mg DHA and
600mg EPA (another n-3 LC PUFA -eicosapentaenoic acid) daily. Each capsule
contained 430mg DHA and 150mg EPA. Participants were administered four capsules
a day, two in the morning and two in the evening. The total n-3 LC PUFAs in the
daily supplement were equivalent to approximately 150g of salmon. Other factors
including nutritional intervention were also considered and closely monitored.
Participants were scheduled one
visit to the laboratory for assessment, every 6 months, for 18 months. For each
assessment visit, participants attended the clinic after an overnight fast, and
a blood sample and physical measurements (height, weight, and blood pressure)
were undertaken. Carotenoids, folate, and vitamin B12 - all associated with
cognitive functioning in the elderly - were assessed.
Apolipoprotein E (ApoE)
genotyping was also conducted in order to examine any differential effect of
treatment due to APOE-epsilon4 allele. Blood was taken at the second and third
assessment points in order to assess 'erythrocyte membrane fatty acid
composition' at each time point. The researchers said, 'n-3 LC PUFA status will
be used to assess compliance/uptake post-hoc and we will also assess whether
changes in n-3 LC PUFA status are associated with any changes on our outcomes'.
This paper is on methodology and protocol of the study
by the researchers where they will be looking into the outcome measures such as:
Primary outcome - Rate of
change in cognitive performance
Secondary outcome - Change in
perceived health status, depressive symptoms, positive and negative affect,
life satisfaction, self-reported cognitive functioning, and functional
capacity; blood pressure; biomarkers of glucose, glycated haemoglobin,
triglycerides, total cholesterol, HDL, LDL, homocysteine, CRP, MDA, and
Since there is no definitive
evidence of cognitive domains that could change by n-3 LC PUFAs, comprehensive
assessment was done on all domains that might benefit from a nutritional intervention.
In conclusion the researchers
stated, 'This is one of the few trials to date to examine the impact of n-3 LC
PUFA supplementation on cognitive decline in cognitively healthy older adults.
Advantages of the current study are the comprehensive assessment of cognitive
functioning and the multiple measurement points, which allow for assessment of
an intervention effect on a trajectory, rather than effects at a specific time
point. The significance for society could be wide-ranging if such an available
and inexpensive dietary treatment has the possibility to safely reduce
cognitive decline in ageing, given the links between cognitive functioning and
the societal and personal burden of dependency and decreased quality of life in
Danthiir,Vanessa et al. The Older People, Omega-3, and
Cognitive Health (EPOCH) trial design and methodology: A randomised,
double-blind, controlled trial investigating the effect of long-chain omega-3
fatty acids on cognitive ageing and wellbeing in cognitively healthy older
adults. Nutrition Journal 2011, 10:117 doi:10.1186/1475-2891-10-117
Morris MC, Evans DA, Tangney CC, Bienias JL, Wilson RS.
Fish consumption and cognitive decline with age in a large community study.
Arch Neurol. 2005 Dec;62(12):1849-53. http://www.ncbi.nlm.nih.gov/pubmed/16216930
Laurin D, Verreault R, Lindsay J, Dewailly E, Holub
BJ. Omega-3 fatty acids and risk of cognitive impairment and dementia. J
Alzheimers Dis. 2003 Aug;5(4):315-22. http://www.ncbi.nlm.nih.gov/pubmed/14624027