My friend Boe noticed her memory slipping in her early sixties. Her parents both had Alzheimer’s and after some years of fierce fighting – an increase in aggressive words can be a sign of the disease - in their nursing home room, they declined so much they no longer recognized each other. Boe joked, “At least it’s peaceful now.”

So she knew what was coming.

We went to doctors who confirmed that she might be right; it was beginning to happen to her. After each doctor’s visit, we’d go out to eat to strategize for a while. Eventually she’d change the subject and she was good company, as always. I considered her noble, and told her so. But I was younger – in my forties - and barely understood.  

We liked to sing on her deck, overlooking the lake in Northern New Jersey, with other friends on summer nights. Sometimes her neighbors on their own decks would even clap.

The last time I saw her, in a nursing home sitting room full of residents slumped in their chairs with their eyes down, I thought she recognized me but wasn’t sure.

On a hunch, I began singing “This land is your land. This land is my land,” and my boyfriend jumped in. We belted it out and Boe, beaming, whispered the words. Music-making is one of the skills that lasts even in people with profound dementia (Devere, 2017). We chose the songs everyone in that age group knew. A woman in a chair nearby looked up and smiled. We crooned “How many roads must a man walk down….” Another resident looked up. For as long as we could, maybe 40 minutes, we sang our hearts out. 

Boe knew the gist of the studies about how to prevent Alzheimer’s, and she exercised and tried to “eat healthy” as she said, but she didn’t transform her habits.  

The vital importance of diet

Cute baby girl yawning on white bed
A diet rich in fish and vegetables appears to lower the risk of cognitive problems characteristic of Alzheimer’s disease.

Boe’s attachment to her diet was too bad because the science is stronger every day: what you eat makes a difference. A study in June drew on data from just over 500 Germans, with an average age of about 70. More than 300 had relatives with Alzheimer’s or were already showing signs of impairment themselves. Those who ate mainly fish, vegetables, whole grains, olive oil, fruits and nuts – which has become known as the Mediterranean Diet - had fewer of the tell-tale amyloid plaques and tau tangles, more brain volume in regions vulnerable to Alzheimer’s disease and better memory (Ballarini et al., 2021).

"We combined several types of data to better understand this protective effect of the diet," lead author Tommaso Ballarini of the German Center for Neurodegenerative Diseases told MedPage Today, on the idea that the diet “might act like a brake against Alzheimer's progression" (George, 2021).

Last year, data from two U.S. trials with more than 6,000 participants also found that eating more fish protected the brain. In one data set with more than 3,300 participants, researchers measured cognitive performance at two, five  and 10 years. The rate of decline in the last five years was slower among those who ate more fish. Eating more vegetables and nuts and drinking less alcohol also helped (Keenan et al., 2020).

So how can I protect myself from cognitive decline?

The best diet advice to date: Eat fatty fish, vegetables, whole grains, fruits and nuts. 

Obesity and type 2 diabetes are significant risk factors for Alzheimer’s, so anything you can do to lose weight and manage blood sugar is essential.  

There is growing evidence that imbalances in the gut affect the brain, which makes the case for a healthy diet overall, with plenty of prebiotic fiber – abundant in garlic, onions, leeks, oats and apples - to feed friendly bacteria.

What about supplements?

So far, no strategy of taking probiotics supplements has been shown to affect Alzheimer’s (Kruger, 2021).   

However, omega-3 supplements have been shown to promote short-chain fatty acids, which are associated with improving gut health (La Rosa, 2018). Research on how these acids affect amyloid plaques is still at the animal-studies stage, focused on mice (Colombo et al., 2021).

Lab investigations and population studies support the idea that omega-3s are good for your brain as well as the rest of you. But studies of supplements have had mixed results. Last year, a small clinical trial suggested why: among people with the APOE4 gene that increases Alzheimer’s risk by a factor of at least four, omega-3s in the blood are less likely to reach the brain (Arellanes et al.,2020).  

The researchers recruited 33 participants who were not cognitively impaired but had a family history of Alzheimer’s, a sedentary lifestyle and a diet low in fatty fish. Fifteen carried an APOE4 gene.

Half of the group was randomly chosen to take more than two grams of the omega-3 fatty acid docosahexaenoic acid (DHA) daily for six months. That’s a high dose; the American Heart Association recommends half that amount, which is about what previous trials have tested.

The other half of the volunteers took placebos, and everyone also took daily B-complex vitamins, which help the body process omega-3s.

The team took samples of blood and cerebrospinal fluid, which required a spinal tap procedure. (You won’t be surprised to hear that the scientists spent two years looking for volunteers; join me in taking a moment to applaud them.)

A hard journey from blood to brain?

Cute baby girl yawning on white bed
Whole fish such as these sockeye salmon fillets, rather than fish oil, may be the better choice for supporting brain health.

At the end of six months, when the researchers took the samples again, they found a big difference between blood and the fluid in the brain, with much less of a DHA increase in the brain’s fluid—which helps explain why supplements don’t work as well as we’d like. Also, participants who didn’t have the APOE4 gene had three times the increase in DHA in their brain’s fluid.

The answer may be to increase dosages to get that DHA to the brain. It might also be, as William Sears, M.D. points out, the synergistic combination of nutrients in whole fish, including selenium, iodine, vitamin B12 and more, has a greater ability to support brain health than DHA or fish oil alone.

The team received funding for a larger trial, which will test whether high doses of omega-3s can slow cognitive decline in APOE4 carriers (Arellanes et al, 2020). We will be watching for their results.

We understand more about diet and the brain every day. However, the fundamentals don’t really change. Stay away from junk. Eat vegetables. Have compassion for your friends struggling with cognitive decline.

And in case I wasn’t clear, eat fish. 

 

Citations:

Arellanes, I. C., Choe, N., Solomon, V., He, X., Kavin, B., Martinez, A. E., Kono, N., Buennagel, D. P., Hazra, N., Kim, G., D'Orazio, L. M., McCleary, C., Sagare, A., Zlokovic, B. V., Hodis, H. N., Mack, W. J., Chui, H. C., Harrington, M. G., Braskie, M. N., Schneider, L. S., … Yassine, H. N. (2020). Brain delivery of supplemental docosahexaenoic acid (DHA): A randomized placebo-controlled clinical trial. EBioMedicine, 59, 102883. https://doi.org/10.1016/j.ebiom.2020.102883  Published July 17, 2020.

Ballarini, T., Melo van Lent, D., Brunner, J., Schröder, A., Wolfsgruber, S., Altenstein, S., Brosseron, F., Buerger, K., Dechent, P., Dobisch, L., Duzel, E., Ertl-Wagner, B., Fliessbach, K., Freiesleben, S. D., Frommann, I., Glanz, W., Hauser, D., Haynes, J. D., Heneka, M. T., Janowitz, D., … DELCODE study group. Mediterranean Diet, Alzheimer Disease Biomarkers and Brain Atrophy in Old Age. Neurology96(24), e2920–e2932. https://doi.org/10.1212/WNL.0000000000012067   Published May 5, 2021.

Colombo, A. V., Sadler, R. K., Llovera, G., Singh, V., Roth, S., Heindl, S., Sebastian Monasor, L., Verhoeven, A., Peters, F., Parhizkar, S., Kamp, F., Gomez de Aguero, M., MacPherson, A. J., Winkler, E., Herms, J., Benakis, C., Dichgans, M., Steiner, H., Giera, M., Haass, C., … Liesz, A. (2021). Microbiota-derived short chain fatty acids modulate microglia and promote Aβ plaque deposition. eLife, 10, e59826. https://doi.org/10.7554/eLife.59826   Published April 13, 2021.

Devere R. Music and dementia: An overview. Practical Neurology. https://practicalneurology.com/articles/2017-june/music-and-dementia-an-overview. Published June 2017.

George J. Alzheimer's pathology linked to diet. Medical News. https://www.medpagetoday.com/neurology/alzheimersdisease/92460. Published May 6, 2021.

Keenan, T. D., Agrón, E., Mares, J., Clemons, T. E., van Asten, F., Swaroop, A., Chew, E. Y., & Age-Related Eye Disease Studies (AREDS) 1 and 2 Research Groups (2020). Adherence to the Mediterranean Diet and Progression to Late Age-Related Macular Degeneration in the Age-Related Eye Disease Studies 1 and 2. Ophthalmology127(11), 1515–1528. https://doi.org/10.1016/j.ophtha.2020.04.030  Epublished  April 26, 2020.

Krüger, J. F., Hillesheim, E., Pereira, A., Camargo, C. Q., & Rabito, E. I. (2021). Probiotics for dementia: a systematic review and meta-analysis of randomized controlled trials. Nutrition reviews79(2), 160–170. https://doi.org/10.1093/nutrit/nuaa037  Published January 9, 2021.

La Rosa, F., Clerici, M., Ratto, D., Occhinegro, A., Licito, A., Romeo, M., Iorio, C. D., & Rossi, P. (2018). The Gut-Brain Axis in Alzheimer's Disease and Omega-3. A Critical Overview of Clinical Trials. Nutrients10(9), 1267. https://doi.org/10.3390/nu10091267  Published September 8, 2018.