A startling omega-3 deficiency may explain women’s Alzheimer’s risk

Analysis of lipids – fat molecules that perform many essential functions in the body – in the blood found there was a noticeable loss of unsaturated fats, such as those that contain omega fatty acids, in the blood of women with Alzheimer’s disease compared to healthy women.

Scientists found no significant difference in the same lipid molecule composition in men with Alzheimer’s disease compared to healthy men, which suggests that those lipids have a different role in the disease according to sex. Fats perform important roles in maintaining a healthy brain, so this study could indicate why more women are diagnosed with the disease.

The study, published on August 20 in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association by scientists from King’s College London and Queen Mary University London, is the first to reveal the important role lipids could have in the risk for Alzheimer’s between the sexes.

Senior author Dr Cristina Legido-Quigley, from King’s College London, said: “Women are disproportionately impacted by Alzheimer’s Disease and are more often diagnosed with the disease than men after the age of 80. One of the most surprising things we saw when looking at the different sexes was that there was no difference in these lipids in healthy and cognitively impaired men, but for women this picture was completely different. The study reveals that Alzheimer’s lipid biology is different between the sexes, opening new avenues for research.”

The scientists took plasma samples from 841 participants who had Alzheimer’s Disease, mild cognitive impairment and cognitively health controls and and were measured for brain inflammation and damage.

They used mass spectrometry to analyze the 700 individual lipids in the blood. Lipids are a group of many molecules. Saturated lipids are generally considered as ‘unhealthy’ or ‘bad’ lipids, while unsaturated lipid, which sometime contains omega fatty acids, are generally considered ‘healthy’.

Scientists saw a steep increase in lipids with saturation – the ‘unhealthy lipids’ – in women with Alzheimer’s compared to the healthy group. The lipids with attached omega fatty acids were the most decreased in the Alzheimer’s group.

Now, the scientists say there is a statistical indication that there is a causal link between Alzheimer’s Disease and fatty acids. But a clinical trial is necessary to confirm the link.

Dr Legido-Quigley added: “Our study suggests that women should make sure they are getting omega fatty acids in their diet – through fatty fish or via supplements. However, we need clinical trials to determine if shifting the lipid composition can influence the biological trajectory of Alzheimer’s Disease.”

Dr Asger Wretlind, first author of the study from King’s College London, said: “Scientists have known for some time that more women than men are diagnosed with Alzheimer’s disease. Although this still warrants further research, we were able to detect biological differences in lipids between the sexes in a large cohort, and show the importance of lipids containing omegas in the blood, which has not been done before. The results are very striking and now we are looking at how early in life this change occurs in women.”

Dr Julia Dudley, Head of Research at Alzheimer’s Research UK says: “In the UK, two in three people living with dementia are women. This could be linked to living longer, or other risk factors like social isolation, education, or hormonal changes from the menopause being at play.

“While this study shows that women with Alzheimer’s had lower levels of some unsaturated fats compared with men, further work is needed. This includes understanding the mechanisms behind this difference and finding out if lifestyle changes, including diet could have a role. Future research should also be carried out in a more ethnically diverse population to see if the same effect is seen.

“Understanding how the disease works differently in women could help doctors tailor future treatments and health advice. Alzheimer’s Research UK is proud to be funding this work that will bring us a step closer to a cure.”

The research was supported by funding from LundbeckFonden and Alzheimer’s Research UK.