2018 in Review: Nutrition and Cognition

by Amylee Amos MS, RDN

What a year it has been. So much has happened: socially, politically, and certainly nutritionally (at least in terms of nutrition science). With each passing year we put a few more more pieces of the complex puzzle of human health together. In this post we are reviewing the most compelling research in nutrition and cognition to come out this past year.

The biggest news of the year for the Bredesen Protocol was our peer reviewed publication in the Journal of Alzheimer’s and Parkinsonism which highlighted the cognitive improvement of 100 patients following the protocol (1). Practitioners from 15 different clinical sites came together to share the results of their patients, demonstrating that the positive outcomes of the Bredesen Protocol are reproducible. This article utilized the largest population of participants of any publication on the Bredesen Protocol to date. As such, it garnered the attention from the medical community needed to continue the process for more research. Hopefully, 2019 will bring with it continued research of the Bredesen Protocol.

Not surprisingly, 2018 brought with it many new studies regarding nutrition and chronic disease, specifically cognitive decline. The Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability (FINGER) was the first study to demonstrate beneficial effect of a 2-year multidomain intervention for cognitive performance. Their results showed that adherence to dietary guidelines predicts subsequent improvement in global cognitive performance among older adults. Specifically, they noted that improvements in diet in old age appear beneficial especially for executive function (2). Studies such as this further implicate diet as a mediator for cognitive health.

Another group looked more specifically at comorbidities heavily influenced by diet and the pathophysiology of Alzheimer’s disease. This intriguing study sought to determine if the presence of modifiable risk factors such as hypertension, obesity, and depression moderate the relationship between levels of beta amyloid plaques in the brain and longitudinal performance on neuropsychological measures in cognitively normal late middle-aged adults. Their results found that the presence of hypertension or obesity in midlife may exacerbate subtle cognitive decline associated with increased production of beta amyloid (3). Studies such as this provide incredible support for utilizing nutrition to prevent Alzheimer’s disease. Both hypertension and obesity are diseases heavily influenced by diet, which demonstrate that by preventing midlife comorbidities we can prevent Alzheimer’s disease.  

In a review study performed at the University of Kentucky, Department of Pharmacology and Nutritional Sciences in 2018, they emphasized the role of brain insulin resistance in memory loss or insulin mediated brain dysfunction, which is sometimes a part of the Alzheimer’s process. In this review, they point out that insulin dysregulation in the brain might cause the decrease in glucose utilization in the aging or Alzheimer’s brain, and showed that intranasal insulin administration and insulin receptor beta transfection could be potential treatments for stopping this cognitive decline by ultimately increasing the brain glucose utilization (4).

Finally, published in December, a double blind placebo controlled trial investigated the cognitive health outcomes of over 3000 people over the course of 13 years, tracking their intake of monounsaturated fatty acids, and polyunsaturated fatty acids, differentiating between omega 6 and omega 3 fats. The experimental group also received an antioxidant supplement. Results showed that total monounsaturated fats, total polyunsaturated fats, and omega 6 fats were positively associated with overall cognitive functioning. However, intake of omega 3 fatty acids was only associated with positive outcomes in the antioxidant supplemented group. This means that higher consumption of omega 3 fats, like those from fatty fish, may only be beneficial among individuals with an adequate antioxidant status (5). Comprehensive, large studies such as this reflect why nutrition science is so convoluted. We cannot focus on or study nutrients in isolation. Nutrients interact and have a synergistic effect.  

What’s the Takeaway from 2018?

Such amazing research came out of 2018. We furthered the research of the outcomes of the Bredesen Protocol, a necessary step as more and more people look to the protocol to reverse or prevent Alzheimer’s disease. We also received even more scientific support regarding the connection between nutrition and cognitive decline. Epidemiological studies such as the FINGER study support that nutrition interventions in midlife support cognitive health as we age, but also that even dietary changes in old age positively impact cognitive function. We learned that comorbidities related to diet such as hypertension and obesity moderate the relationship between beta amyloid plaques, the hallmark of Alzheimer’s disease, and cognitive decline. Our knowledge of central insulin resistance and the impact of insulin resistance pathology in Alzheimer’s disease was thoroughly reiterated. And finally, we learned that nutrition science is complex (actually, we already knew that), but the unsaturated fats and antioxidant study re-emphasized that we need to look at the diet as a whole, not as a series of ingested nutrients.

Of course, countless other studies were published this year, but these were a few that caught our eye. Stay tuned for more to come in 2019!

References:

  1. Bredesen, D.E., Sharlin, K., Jenkins, D., Okuno, M., Youngberg, W., et al. (2018) Reversal of Cognitive Decline: 100 Patients. J Alzheimers Dis Parkinsonism 8: 450.
  2. Lehtisalo, J., Levalahti, E., Lindstrom, J., Hanninen, T., Paajanen, T., Peltonen, M., Antikainen, R., Laatikainen, T., Strandberg, T., Soininen, H., Tuomilehto, J., Kivipelto, M., & Ngandu, T. (2018). Dietary changes and cognition over 2 years within a multidomain intervention trial—The Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability (FINGER). Alzheimer’s and Dementia, 1-8.
  3. Clark, L. R., Kosick, R.L., Allison, S.L., Berman, S.E., Norton, D., Carlsson, C.M., Batthauser, T.J., Bendlin, B.B., Christian, B.T., Chin, N.A., Asthana, S., & Johnson, S.C. (2018). Hypertension and obesity moderate the relationship between b-amyloid and cognitive decline in midlife. Alzheimer’s and Dementia, 1-11.
  4. Frazier, H.N., Ghoweri, A.O., Anderson, K.L., Lin, R., Porter, N.M., & Thibault, O. (2019). Broadening the definition of brain insulin resistance in aging and Alzheimer’s disease. Experimental Neurology, 313: 79-87.
  5. Assmann, K, E.,  Adjibade, M., Hercberg, S.,  Galan, P., & Kesse-Guyot, E., (2018). Unsaturated Fatty Acid Intakes During Midlife Are Positively Associated with Later Cognitive Function in Older Adults with Modulating Effects of Antioxidant Supplementation. The Journal of Nutrition, 148(12): 1938–1945