Diet may be a strong contributor to Alzheimer’s disease
In last week’s article, (dated Sept. 27), I wrote about general dementia prevention. I thought it would be appropriate to follow up with an article on Alzheimer’s disease, one of the most debilitating neurodegenerative diseases. Its incidence continues to rise in lockstep with the fact that we are living longer, for as we age, our risk for the disease increases exponentially (Neurology 1998;51(3):728).
There is more and more evidence that points to an association between diet and Alzheimer’s disease. Also, there may be a more definitive way to estimate disease risk and progression. This involves white matter hyperintensities (WMH) found in an MRI scan of the brain. These WMH may be tied, at least partially, to diet. Vitamin D levels are also potentially important in Alzheimer’s risk. This article will discuss and explore the potential associations in more detail by looking at the evidence.
The potential significance of white matter hyperintensities
What are WMH and why are they important? White matter hyperintensities represent small vessel cerebrovascular disease. Cerebrovascular disease involves a group of disorders that affect blood vessels, causing a significantly diminished or lack of blood flow to the brain (www.medicalnewstoday.com). For example, atherosclerosis or plaques in the arteries can be a cause, potentially leading to a cerebrovascular accident — or what we typically call a stroke.
One study utilized the Washington Heights/Inwood Columbia Aging Project (WHICAP), an observational study in Manhattan. It found significantly increased risk of Alzheimer’s with WMH, while the atrophy of the hippocampus did not correlate with disease diagnosis (Arch. Neurol. online Sept. 2012). The hippocampus is the part of the brain involved in formation, organization and storage of memory.
The study suggests that these WMH may be important for predicting disease risk and progression, even potentially more so than hippocampal atrophy or shrinkage. Further study is needed for these preliminary findings, though they are very intriguing.
If we are looking at the WMH, then the risk factors for cerebrovascular disease, including high blood pressure, diabetes and obesity, become important. This is where dietary aspects may play a role. The authors suggest that lifestyle modifications would impact cerebrovascular disease risk, which ultimately could reduce Alzheimer’s risk.
In an observational study called the Kame Project cohort, a modest dietary change had dramatically beneficial results. Those who drank fruit juice and vegetable juice three times or more a week, compared to those who drank less than once a week, saw a 76 percent reduction in the risk of Alzheimer’s disease (Am. J. Med. 2006 Sep;119(9):751-759). The authors concluded that fruit/vegetable juice may play a vital role in delaying the onset of dementia.
Ironically, at the same time that the WMH results of the previously mentioned study were published, Mark Bittman wrote in a recent article that Alzheimer’s disease has been referred to as “type 3 diabetes” (www.nytimes.com). This phrase has been around since the publication of a 2005 journal article (J. Alzheimers Dis. 2005 Feb;7(1):63-80). The reason for this phrase is that there is potentially an impaired insulin response in the brain of Alzheimer’s disease patients. It is not the phrase itself, but rather the implication of the phrase, that is important. Insulin helps the body regulate and utilize blood sugar. If the brain is not able to metabolize sugar in early Alzheimer’s, this mechanism may contribute to the disease.
To compound this potential lack of insulin response, a recent study focused on macronutrients, or more specifically carbohydrates, and their impact on Alzheimer’s. But what does Alzheimer’s disease have to do with carbohydrates?
The results of the study showed that those who ate a high-carbohydrate diet were at an 89 percent increased risk of developing dementia, such as Alzheimer’s disease (J. Alzheimers Dis. Online July 17, 2012). This should not be shocking, since carbohydrates become sugar when broken down in the body. It seems to fit what the authors are saying in the previously mentioned 2005 study conclusions.
It turns out that type 2 diabetes patients have twice the risk of developing Alzheimer’s (Medscape.org). If we control the glucose (sugar) levels intensely in diabetics, will this reduce their risk of Alzheimer’s? Unfortunately, the ACCORD-MIND trial, a randomized clinical trial, considered the gold standard of studies, did not show a difference after 40 months between the group that had intensive control of sugars compared to standard control (Lancet Neurol. 2011;10:969-977).
The impact of vitamin D
We can’t seem to get away from vitamin D. It appears to be involved in so many different chronic diseases. In the most recent meta-analysis (a group of 37 studies), it was found that those with Alzheimer’s have a lower vitamin D blood level than those without the disease (Neurology. 2012;79:1397-1405). I have a patient with moderately severe Alzheimer’s who is not only insufficient (<30 ng/ml) but deficient (<20 ng/ml) in vitamin D. When I first tested the blood levels, the patient had a vitamin D level of 13 ng/ml.
What is also interesting is that this same patient, after being on a high nutrient, plant-rich diet for a month, had an approximately 45-minute lucid moment, something that had not been seen for years according to the caregiver. This is only anecdotal, and it has only been a month, so that the lucid moment may have been a coincidence. We will have to stay tuned to see what happens.
Ultimately, what is critically important is to realize that Alzheimer’s disease, just like many other chronic diseases, has modifiable risk factors that involve lifestyle choices. Pardon the pun, but I hope this gives you food for thought.
Dr. Dunaief is a speaker, author and local lifestyle medicine physician focusing on the integration of medicine, nutrition, fitness and stress management. For further information, go to the website www.medicalcompassmd.com and/or consult your personal physician.