What Causes Cognitive Decline — And Can Nutrition Slow It?

Cognitive decline is one of the most frightening prospects most of us will ever face, whether we are noticing early changes in ourselves or watching them unfold in someone we love. I have spent the better part of 20 years conducting clinical research at the University of Miami Miller School of Medicine on exactly this question, and I can tell you that cognitive decline is not a single, mysterious event but a set of identifiable biological processes. Understanding those processes is what allows us to talk honestly about what nutrition can and cannot do about them.

What Cognitive Decline Actually Means

Cognitive decline is a spectrum, not a single condition, and knowing where a change falls on that spectrum is the difference between needless fear and appropriate action. Precision in language matters here because the words people use interchangeably actually describe quite different situations. Normal cognitive aging refers to the gradual, expected slowing of processing speed and the occasional memory lapse that accompany a healthy aging brain. Mild cognitive impairment refers to a measurable decline that is greater than normal aging but does not yet interfere significantly with independent daily living, and it does not inevitably progress. Dementia, of which Alzheimer’s disease is the most usual form, refers to a decline severe enough to impair daily function, and it is a distinct pathological process. Recognizing the early signs of cognitive decline, such as repeated forgetfulness of recent events, difficulty with familiar tasks, or trouble following conversations, is valuable not because every change is serious but because early clarity allows for the best possible plan.

The Identified Causes — What the Science Shows

The biology of cognitive decline is now understood well enough to name its principal drivers, and each of them is a place where nutrition has a plausible point of entry. First, neuroinflammation, the chronic low-grade inflammation within the brain, is increasingly recognized as a central engine of cognitive decline, and my own research has focused heavily on the immune and inflammatory dimension of this process (Lewis et al., 2023). Second, oxidative stress damages neurons over time as free radicals overwhelm the brain’s antioxidant defenses. Third, mitochondrial dysfunction starves neurons of the energy they require to function and survive.

Fourth, vascular changes reduce blood flow to the brain, depriving it of oxygen and nutrients. Fifth, the gut-brain axis, the bidirectional communication between the gut microbiome and the brain, influences neuroinflammation in ways that science is only beginning to map fully. Sixth, nutrient deficiencies, which are remarkably common in older adults, deprive the brain of the raw materials it needs for repair and signaling. What I find most compelling about this list is that these mechanisms are interconnected, and a nutritional strategy that addresses several of them at once is far more rational than any approach aimed at a single target.

What Nutrition Cannot Do

I am going to tell you something that most supplement companies will never say because it is the foundation of any trust I hope to earn. Nutrition cannot cure dementia, it cannot reverse advanced pathological decline, and it cannot replace medical care for a diagnosed neurological disease. Any company that implies otherwise is engaging in precisely the kind of predatory marketing that gives this entire industry a deserved bad name, and I will not do it. What nutrition can do is support the brain’s underlying biology in ways that are biologically coherent and, in the populations we have studied, measurable. Being honest about this boundary is not a weakness in my argument. It is the reason you can believe the rest of what I tell you.

What Nutrition Can Do — The Research

Within those honest limits, the research my colleagues and I have published offers a genuinely encouraging picture of what nutrition can support, and this is the work of which I am proudest. In a 12-month clinical study of adults with moderate-to-severe cognitive impairment, an aloe polysaccharide-based multinutrient formula produced statistically and clinically significant improvements in cognitive functioning, a result that is uncommon in this population (Lewis et al., 2013). We then demonstrated that the same intervention was associated with improvements in brain-derived neurotrophic factor and that these changes related meaningfully to cognition and immune function (Martin et al., 2017; Stillman et al., 2020). In parallel work in multiple sclerosis, another condition defined by neuroinflammation and immune dysregulation, the same nutritional approach was associated with improved immune functioning, fewer infections, and improvements in quality of life and symptom severity (McDaniel et al., 2020a; McDaniel et al., 2020b). Most recently, we characterized how the formula shifts the Th1/Th2 immune ratio in a favorable, anti-inflammatory direction in both Alzheimer’s disease and multiple sclerosis populations (Lewis et al., 2023; Lewis et al., 2024). Taken together, this body of work shows that a well-designed nutritional formula can act on the inflammatory and neurotrophic mechanisms that sit at the heart of cognitive decline.

The Protocol I Follow and Recommend

My own protocol follows directly from this research because I would never recommend an approach I do not personally practice. I support the foundations first with sleep, daily exercise, a whole-food and plant-based diet, and active stress management, and then I add a broad-spectrum nutritional formula built around aloe polysaccharides. I chose the polysaccharides because they are the compounds my research has centered on for two decades and because they support the gut-brain axis and immune balance in a way that diet alone cannot, given that almost no one eats concentrated aloe polysaccharides. I add N-acetyl cysteine for antioxidant support, dioscorea for the diosgenin that supports the brain’s neurotrophic and anti-inflammatory signaling, rice bran for its broad spectrum of anti-inflammatory phytonutrients, and sunflower lecithin for the choline the brain uses to build memory-related neurotransmitters. This is the clinical reasoning that produced Daily Brain Care, and it is the formula I take every day.

Can It Be Reversed — The Honest Answer

The question almost everyone is afraid to ask is whether cognitive decline can be reversed, and you deserve a precise answer rather than false comfort or false despair. Advanced, pathological decline cannot be reversed by nutrition, and I will not pretend otherwise. What the science supports is more nuanced and, in my view, genuinely hopeful, which is that nutritional intervention can support cognitive functioning and, in the clinical populations we studied, was associated with measurable improvement on validated cognitive measures over the course of a year (Lewis et al., 2013). Whether that reflects the slowing of decline, the support of remaining function, or some combination is a question science is still working to answer with full confidence. What I can say without hesitation is that the earlier you act to support your brain’s biology, the more you have to protect, and acting early is entirely within your control.

References

1. Lewis, J. E., McDaniel, H. R., Agronin, M., Loewenstein, D., Riveros, J., Mestre, R., Martinez, M., Colina, N., Abreu, D., Konefal, J., Woolger, J. M., & Ali, K. H. (2013). The effect of an aloe polymannose multinutrient complex on cognitive and immune functioning in Alzheimer’s disease. The Journal of Alzheimer’s Disease, 33, 393-406. doi: 10.3233/JAD-2012-121381. PMID: 22976077. View
2. Martin, A., Stillman, J., Miguez, M. J., McDaniel, H. R., Konefal, J., Woolger, J. M., & Lewis, J. E. (2017). The effect of dietary supplementation on brain-derived neurotrophic factor and cognitive functioning in Alzheimer’s dementia. Journal of Clinical and Translational Research, 3(3), 337-343. PMID: 30895275. View
3. Stillman, J., Martin, A., Miguez, M. J., McDaniel, H. R., Konefal, J., Woolger, J. M., & Lewis, J. E. (2020). Relationship between brain-derived neurotrophic factor and immune function during dietary supplement treatment of elderly with Alzheimer’s dementia. Journal of Clinical and Translational Research, 5(2), 68-75. View
4. McDaniel, H. R., LaGanke, C., Bloom, L., Goldberg, S., Hensel, J., Lantigua, L. A., Lages, L. C., Atlas, S. E., Woolger, J. M., & Lewis, J. E. (2020). The effect of broad-spectrum dietary supplementation on quality of life, symptom severity, and functioning in multiple sclerosis. Journal of Dietary Supplements, 17(6), 718-732. doi: 10.1080/19390211.2019.1651435. View
5. McDaniel, H. R., LaGanke, C., Bloom, L., Goldberg, S., Lages, L. C., Lantigua, L. A., Atlas, S. E., Woolger, J. M., & Lewis, J. E. (2020). The effect of a polysaccharide-based multinutrient dietary supplementation regimen on infections and immune functioning in multiple sclerosis. Journal of Dietary Supplements, 17(2), 184-199. doi: 10.1080/19390211.2018.1495675. View
6. Lewis, J. E., McDaniel, H. R., Woolger, J. M., & Khan, S. (2023). The characterization of the Th1/Th2 ratio in moderate-severe Alzheimer’s disease patients and its response to an aloe polymannose-based dietary supplement. The Journal of Alzheimer’s Disease, 96(4), 1723-1737. doi: 10.3233/JAD-230659. PMID: 38007658. View
7. Lewis, J. E., McDaniel, H. R., Woolger, J. M., Anzola, E., & Kraft, G. (2024). The characterization of the Th1/Th2 ratio in multiple sclerosis patients and its response to a dietary supplement regimen. Journal of Dietary Supplements, 21(6), 771-790. doi: 10.1080/19390211.2024.2386259. View

These statements have not been evaluated by the Food and Drug Administration. Daily Brain Care is a dietary supplement and is not intended to diagnose, treat, cure, or prevent any disease. The research described on this page was conducted in clinical populations and is presented to explain the nutritional science behind the formula, not to claim that the product treats any medical condition. Always consult your physician before beginning any new supplement, particularly if you take medication or have a diagnosed health condition.