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No Effect of Omega-3 on Cognitive Decline, Says Study

Last updated Aug. 30, 2015

Approved by: Krish Tangella MD, MBA, FCAP

Age-related macular degeneration (AMD) is a neurodegenerative disorder of the eye. Research has shown that individuals with AMD develop cognitive impairment, similar to that observed in patients with Alzheimer’s disease.


A large clinical study conducted by the National Institutes of Health (NIH), USA, involving participants with age-related macular degeneration concluded that long-chain polyunsaturated fatty acids or LCPUFAs (omega-3 fatty acids), lutein, and zeaxanthin did not have any significant effect on their cognitive decline.

Age-related macular degeneration (AMD) is a neurodegenerative disorder of the eye. Research has shown that individuals with AMD develop cognitive impairment, similar to that observed in patients with Alzheimer’s disease. A few studies have reported that a nutrition high in omega-3 fatty acids influences positive cognitive ability in AMD patients.

The current study is the largest and longest one undertaken to investigate the effect of omega-3 fatty acid and some other supplements on cognitive decline in AMD. Under the auspices of the Age-Related Eye Disease Study 2 (AREDS-2), a randomized clinical trial was conducted engaging 4203 patients and following them for a period of 5 years. The participants had early or intermediate AMD, with an average age of 72.7 years. Women constituted 57.5% of the study population.

The participants were assigned to one of the following treatments:

  1. Placebo
  2. Omega-3 fatty acids
  3. Lutein, zeaxanthin
  4. Omega-3 and lutein/zeaxanthin

The omega-3 fatty acid supplements used for the study include docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA).  

A cognitive test was administered to the participants at the beginning of the study (baseline), followed by tests 2 years and 4 years later. The tests were given to assess delayed recall, memory, speed of processing information, etc. The composite scores were derived after adjusting for age, sex, race, history of hypertension, education, cognitive score, and depression score.

The results showed that:

  • Compared to baseline scores, there were no significant differences in composite scores between participants who received omega-3 supplements and those who did not.
  • Additional supplementation with lutein and zeaxanthin did not influence the scores either.

The lead author of the study, Dr. Emily Chew, says in the NIH Press Release, “Contrary to popular belief, we didn’t see any benefit of omega-3 supplements for stopping cognitive decline.”

AMD and Alzheimer’s disease are both neurodegenerative disorders with declining cognitive function. The findings from this clinical trial helps us understand that omega-3 supplements at the concentrations tested in the study did not influence cognition positively. 

As Dr. Lenore Launer, a co-author in the study, says, “The AREDS2 data add to our efforts to understand the relationship between dietary components and Alzheimer’s disease and cognitive decline. It may be, for example, that the timing of nutrients, or consuming them in a certain dietary pattern, has an impact. More research would be needed to see if dietary patterns or taking the supplements earlier in the development of diseases like Alzheimer’s would make a difference.”

By Mangala Sarkar, PhD

References and Information Sources used for the Article:


Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: Aug. 30, 2015
Last updated: Aug. 30, 2015