Mediterranean Diet and Dementia

Did you know that you have two brains? If you didn’t, don’t worry, scientists have only really cared about the brain with a capital 'B' up until a few years ago, so you’re not far out of the loop. Your second brain is the Enteric Nervous System (ENS). AKA: Your Gut. While your brain may have  85 billion neurons, your gut has 500 million neurons and uses 50% of your body’s dopamine and 95% of your body’s serotonin1.

So what does the ENS do? That’s a good question, and I’ll let you know once the neuroscientists figure it out. But what we do know is that the ENS has a lot of influence on the CNS (Central Nervous System-“The Brain”). This gut-brain connection is fascinating though for all of your Foodies, as it means that there may be undiscovered reasons why your diet is promoting brain health.

Perhaps no neurological disorder could use some hope right now more than dementia. Unfortunately, for those of us at risk for dementia, like Alzheimer’s Disease (AD), there aren’t a lot of effective treatments. There are no known cures for AD, and the best doctors can do right now is delay the inevitable and manage symptoms, even with drug treatments like Aricept (Meta-analysis2). When it comes time for your retirement years though, delaying the onset of AD by even five years can make a world of difference for you and your family, so its nothing to scoff at.

You know who else shouldn’t be scoffed at? The Italians, Greeks, and Turks. These cultures (among others) all share a similar diet, with lots of fish, fresh veggies, fresh fruit, healthy oils, and a splash of wine (finally a healthy diet with room for wine!3). These Mediterranean cultures also tend to have a lower prevalence of dementia compared to North America4-5. So much later, in fact, that scientists have studied effects of this Mediterranean Diet (MeDi) as a treatment for dementia. A meta-analysis found that adherence to the MeDi could reduce your risk of developing dementia by up to 33%6.

So why is the MeDi seemingly so good at delaying the onset of dementia? That’s a good question. Scientists have some hypotheses that they are currently testing. The MeDi contains some antioxidants, which might be one way it fights AD7. While the MeDi may be good for your heart, that can’t explain all of the brain-related benefits8. Alternatively, the MeDi could fight inflammation because of a few chemicals (Tyrosol and caffeic acid) found in two of my favourite ingredients-olive oil and red wine7. The MeDi may even help regulate insulin9, which is good news since some scientists are starting to call AD Type 3 diabetes10.

So which of these hypotheses is the correct one?

What if I told you that there could be more than one correct hypothesis? One thing that separates out the research on the MeDi is the emphasis on the whole package. Most nutraceutical research focuses on the effects of single nutrients, but MeDi research emphasizes that it's likely not one nutrient doing the heavy lifting, but a complex set of nutrients that collectively promote brain health. The brain is by far the most complex thing in the known universe (as decided by a brain), so why would we think that a single molecule is going to cure something as complex as dementia? While there can be single molecules that do help out (Aricept is still great at managing symptoms for AD), the much more realistic solution of neurological disorders is going the be complex. I see the MeDi as an essential shift in scientific thinking on treatments towards viewing brain health as the result of holistic effort on multiple fronts and an appreciation of its complexity. Much to my dismay, red wine will not cure AD, but in conjunction with a good Greek salad, some hummus (#millennialstaple), and some rosemary-lemon-baked fish, it just might delay its onset enough to make a difference.

Ty the Neuro Guy is a cognitive neuroscience graduate student at the University of Utah and the Research Director for Branch Out Neurological Foundation. Inspired by the creative knowledge translation, Ty helps promote scientific literacy through this blog. You can look forward to an article each month helping explain the science of NeuroCAM. If you have any questions or comments about this article or overall blog, feel free to email Ty McKinney at research@branchoutfoundation.com.

 

References

  1. https://www.newscientist.com/article/mg21628951.900-gut-instincts-the-secrets-of-your-second-brain
  2. Blanco-Silvente, L., Castells, X., Saez, M., Barceló, M. A., Garre-Olmo, J., Vilalta-Franch, J., & Capellà, D. (2017). Discontinuation, efficacy, and safety of cholinesterase inhibitors for Alzheimer’s disease: a meta-analysis and meta-regression of 43 randomized clinical trials enrolling 16 106 patients. International Journal of Neuropsychopharmacology20(7), 519-528.
  3. Morris, M. C., Tangney, C. C., Wang, Y., Sacks, F. M., Bennett, D. A., & Aggarwal, N. T. (2015). MIND diet associated with reduced incidence of Alzheimer's disease. Alzheimer's & Dementia11(9), 1007-1014.
  4. Langa, K. M., Larson, E. B., Crimmins, E. M., Faul, J. D., Levine, D. A., Kabeto, M. U., & Weir, D. R. (2017). A comparison of the prevalence of dementia in the United States in 2000 and 2012. JAMA Internal Medicine177(1), 51-58.
  5. Kosmidis, M. H., Vlachos, G. S., Anastasiou, C. A., Yannakoulia, M., Dardiotis, E., Hadjigeorgiou, G., & Scarmeas, N. (2018). Dementia Prevalence in Greece: The Hellenic Longitudinal Investigation of Aging and Diet (HELIAD). Alzheimer disease and associated disorders.
  6. Singh, B., Parsaik, A. K., Mielke, M. M., Erwin, P. J., Knopman, D. S., Petersen, R. C., & Roberts, R. O. (2014). Association of Mediterranean diet with mild cognitive impairment and Alzheimer's disease: a systematic review and meta-analysis. Journal of Alzheimer's disease39(2), 271-282.
  7. Frisardi, V., Panza, F., Seripa, D., Imbimbo, B. P., Vendemiale, G., Pilotto, A., & Solfrizzi, V. (2010). Nutraceutical properties of Mediterranean diet and cognitive decline: possible underlying mechanisms. Journal of Alzheimer's Disease22(3), 715-740.
  8. Scarmeas, N., Stern, Y., Mayeux, R., & Luchsinger, J. A. (2006). Mediterranean diet, Alzheimer disease, and vascular mediation. Archives of neurology63(12), 1709-1717.
  9. Salas-Salvadó, J., Bulló, M., Estruch, R., Ros, E., Covas, M. I., Ibarrola-Jurado, N., ... & Romaguera, D. (2014). Prevention of diabetes with Mediterranean diets: a subgroup analysis of a randomized trial. Annals of internal medicine160(1), 1-10.
  10. Blázquez, E., Velázquez, E., Hurtado-Carneiro, V., & Ruiz-Albusac, J. M. (2014). Insulin in the brain: its pathophysiological implications for States related with central insulin resistance, type 2 diabetes and Alzheimer’s disease. Frontiers in endocrinology5, 161.