Last updated on September 8th, 2023 at 12:46 pm
I have previously reviewed whether vitamin D supplements had any effect on reducing the risk of dementia or Alzheimer’s disease. Unfortunately, that study was far from perfect, and it was difficult to determine if vitamin D had any positive effect on cognitive decline.
I then came across a recent systematic review (and as I’ve said many times, these are at the top of the hierarchy of medical research) that examined many of the studies that attempted to link vitamin supplements to improved outcomes of dementia and Alzheimer’s disease.
As I usually do, I will examine the results of the published article and then give you my critique on the quality of the data.
What is Alzheimer’s disease?
Before I proceed, it’s important to describe what we currently know about Alzheimer’s disease (AD). It is a chronic neurodegenerative disease that usually starts slowly and worsens over time. It accounts for 60-70% of dementia cases, even though the terms are sometimes used interchangeably. Alzheimer’s disease is a form of dementia. The other forms of dementia include Lewy body dementia, frontotemporal disorders, vascular dementia, and mixed dementia, which is a combination of two or more of the different forms of dementia.
Amyloid plaques (caused by amyloid beta, or Aβ), phosphorylated tau tangles (pTau), and neurofibrillary tangles are generally easily visible pathologies that can be observed by microscopic analysis of brain tissue from autopsies of those potentially afflicted by AD. These plaques and tangles seem to affect nerve functioning. Despite these observations, the precise pathophysiology, or development, of the disease is not known.
Since amyloid plaques are often identified in patients with Alzheimer’s disease, a large amount of research is focused on attacking those plaques as a way to reverse the effect on nerves which leads to AD.
The causes of AD are unknown (notice how much we do not know about this disease), although it is speculated that it is mostly genetically related, with a large number of genes that underlie this relationship.
And since we have no clear understanding of the etiology and pathophysiology of AD, there are no effective treatments available today for the disease, although there are some drugs that target the amyloid plaques but have not been shown to change the course or outcomes of AD.
There are a couple of medications that help manage some of the symptoms of the disease, but they are certainly not cures. There are several drugs at the very earliest stages of development that may hold out hope to treat the underlying disease.
One more thing that needs to be made clear. There are no biological tests for Alzheimer’s disease — usually, you can only find the amyloid plaques and other pathologies in post-mortem autopsies. Unfortunately. in the absence of an autopsy, clinical diagnoses of AD are “possible” or “probable”, based on other findings, such as memory tests and other methods.
In the United States, about 10.7% of seniors (≥65 years) currently have Alzheimer’s dementia, and this proportion is expected to grow with the aging population. The economic burden of AD is expected to surpass $2.8 trillion by 2030.
Vitamin supplements, dementia, and Alzheimer’s disease paper
In the systematic review published on 28 February 2022 in the journal Nutrients, Sonia Santander Ballestín, MD, Department of Pharmacology, Physiology and Legal and Forensic Medicine, Faculty of Medicine, University of Zaragoza, Spain, and colleagues reviewed articles that examined any links between vitamin supplements and one of the forms of dementia, including Alzheimer’s disease.
This review included 14 articles that studied B complex vitamins, 10 articles that focused on vitamin D, and three that included vitamin E.
The researcher’s key results were:
- Combined use of folic acid and vitamin B12 may be linked to a lower risk of cognitive decline.
- After 24 months of supplementation of vitamin B12 and folic acid, there was a statistically significant increase from baseline to 24 months in cognitive tests.
- Thiamine, also known as vitamin B1, did not only prove to have a positive impact on cognitive performance when given alone but also when given in combination with folic acid
- Because of the quality of research, vitamin D supplementation trials were not conclusive in assessing the potential benefits that vitamin D might have on cognition.
- Short-term vitamin D3 supplementation did not have a significant impact on global cognitive function.
- Neither vitamin E, selenium supplementation, nor their combination had any effect on the course or outcomes of dementia.
- Low-dose vitamin E and vitamin C supplements may show a positive effect on cognitive performance, but the evidence is weak and more studies would be necessary to provide us with definitive evidence to support its use.
The authors concluded:
The findings of this systematic review suggest that supplementation of B Complex vitamins, especially folic acid, may have a positive effect on delaying and preventing the risk of cognitive decline. Ascorbic acid (vitamin C) and a high dose of vitamin E, when given separately, also showed positive effects on cognitive performance, but there is not sufficient evidence to support their use. The results of vitamin D supplementation trials are not conclusive in assessing the potential benefits that vitamin D might have on cognition.
This study provided a thorough review of the best research that attempted to link vitamin supplements and the outcomes of dementia and Alzheimer’s disease. It appears that B vitamins, especially thiamine, had the best results in improving cognitive function in patients with dementia. And combining that with folic acid gave the best results.
We obviously need more research into the role of vitamin supplements and dementia, especially Alzheimer’s disease. But this is a first step.
Although I am not a fan of supplements, unless one has a diagnosed deficiency of the vitamin, you might want to consider thiamine and folic acid as you get older.
- Gil Martínez V, Avedillo Salas A, Santander Ballestín S. Vitamin Supplementation and Dementia: A Systematic Review. Nutrients. 2022 Feb 28;14(5):1033. doi: 10.3390/nu14051033. PMID: 35268010; PMCID: PMC8912288.