“There’s a growing body of evidence linking elevated blood sugar to memory problems.”
Mainstream media is catching on, folks. The quote above, taken from this story from NPR over three years ago, is reflective of the growing awareness among the medical community and laypeople alike that there might actually be something to the wild and crazy notion of Alzheimer’s disease and cognitive impairment as “type 3 diabetes” or “diabetes of the brain.” I have written about this over and over again and need not rehash the details here. (If you want to know the full story, consider purchasing my book, The Alzheimer’s Antidote.) Even The New York Times published a piece just the other day profiling a famous chef who is using a low-carb, high-fat diet to fight dementia. (Shout out to liberal use of butter abd MCT oil in her morning coffee!)
The NPR article is pretty good. It gets the point across while being very succinct – a feat I have proven I am totally incapable of. What I like best about it is that it references this paper, the key finding of which is that elevated blood glucose may be a risk for dementia even at levels lower than the diabetic range. This is not news to me, and probably not to you, but it’s nice to see this getting out to the general public, among whom it probably is news. (Or should have been a few years ago when this came out.) It’s not news to us because you and I already know that hyperinsulinemia alone—not high glucose, but high insulin—is an independent risk factor for developing Alzheimer’s disease. In fact, compared to people with “normal” insulin levels, those who are not diabetic but are hyperinsulinemic have double the risk of developing AD.
But back to the paper discussed in the article:
The study subjects had the following characteristics:
N (total number of subjects) = 2067, of which 232 were diagnosed diabetics and 1835 were non-diabetics.
Age range: 71-81
Race: 1863 Caucasian, 100 Black, 67 Asian, and 37 “other”
Treated for hypertension: 1437 subjects, split as follows:
Non-diabetics*: 1248 out of 1835 (68%)
Diabetics: 189 out of 232 (81.5%)
*For the non-diabetics, my hunch is that although they were not diagnosed “diabetics,” perhaps they had raging hyperinsulinemia. As I wrote about in the insulin series, for many people, glucose and A1c will be the last things to alert a doctor as to the presence of metabolic abnormalities stemming from chronically elevated insulin. Oddly enough, otherwise “idiopathic” hypertension is a big clue that comes first for many people. [Too bad some doctors have no clue.] Almost 24% of these “non-diabetics” also had coronary artery disease and 11% had cerebrovascular disease. Just sayin’.)
According to the study:
In both diabetics and non-diabetics, higher blood glucose
is correlated with higher risk for dementia.
(Source: P. Crane et al., 2013.)
“During a median follow-up of 6.8 years, dementia developed in 524 participants (74 with diabetes and 450 without). Among participants without diabetes, higher average glucose levels within the preceding 5 years were related to an increased risk of dementia (P = 0.01); with a glucose level of 115 mg per deciliter (6.4 mmol per liter) as compared with 100 mg per deciliter (5.5 mmol per liter), the adjusted hazard ratio for dementia was 1.18 (95% confidence interval [CI], 1.04 to 1.33). Among participants with diabetes, higher average glucose levels were also related to an increased risk of dementia (P = 0.002); with a glucose level of 190 mg per deciliter (10.5 mmol per liter) as compared with 160 mg per deciliter (8.9 mmol per liter), the adjusted hazard ratio was 1.40 (95% CI, 1.12 to 1.76).”
Bottom line: higher blood sugar, higher risk for dementia. Is this an association? A correlation? Yes. But as you can imagine, if I didn’t have a very strong suspicion there’s some degree of causation there, I wouldn’t have written a book about it. And I have an even stronger suspicion that if they had measured these subjects’ insulin levels, there would have been an even stronger correlation. (How many of you would join me in wagering money that these people have what Dr. Kraft calls "diabetes in-situ"?)
The NPR article cites another paper that had similar findings: “… even in the absence of manifest type 2 diabetes mellitus or impaired glucose tolerance, chronically higher blood glucose levels exert a negative influence on cognition, possibly mediated by structural changes in learning-relevant brain areas.” In plain English: people with higher blood glucose had worse cognition than people with lower glucose, and this was probably due to changes to the physical structure of the brain. Also: “… beneficial effects of lower HbA1c on memory are in part mediated by hippocampal volume and microstructure.” People with lower blood sugar literally had larger hippocampi. (Hippocampuses?) Alzheimer’s researchers have noted substantial brain atrophy in AD patients. The brain actually shrinks. Based on these observations, the authors concluded, “Therefore, strategies aimed at lowering glucose levels even in the normal range may beneficially influence cognition in the older population, a hypothesis to be examined in future interventional trials.” I am torn here in my feelings, because on the one hand, I feel quite validated and I trust that my book will help a lot of people. But on the other hand, I am disappointed that there seems to be so little interest in pursuing such trials. Drugs? Yes. Dietary strategies? Not so much.
Still, overall, the article does a good job of conveying the pertinent information quickly and clearly. Higher blood sugar ---> worsening cognitive function. That’s all people really need to know, except that they might benefit from some tips on how to not have high blood sugar. Enter the dietary recommendations:
“What we eat is important. ‘Consuming a diet rich in fiber, vegetables, fruit, fish, and whole-grain products’ is recommended, Floel wrote to us in an email.” (Flöel being Agnes Flöel, one of the authors of the latter study.)
Fiber, vegetables, fruit, fish, and whole-grain products.
Let me rewrite that, boiled down to its essential elements: carbohydrate, carbohydrate, carbohydrate, fish, and carbohydrate.
Before anyone gets the wrong message here, no, I am not saying that fiber, vegetables and fruit are “bad” for us. I’m simply pointing out that, having authored a paper showing an association between higher blood glucose levels and “lower memory and reduced hippocampal microstructure,” Dr. Flöel then recommends a diet that is
entirely “rich in” carbohydrate, with the exception of fish.
The cognitive dissonance is profound.
I don’t know why it is so, so difficult for doctors and researchers to even acknowledge the possibility that it’s okay to eat more fat, more egg yolks, and more animal protein, and to decrease consumption of fruit and those “healthy whole grains,” especially for individuals whose cognition is becoming compromised from a reduced ability to harness energy from glucose. (Certainly the answer is not to flood their bodies with yet more glucose, in the way they give hyperinsulinemic type 2 diabetics more insulin and wonder why their health only continues to deteriorate.) I suspect it’s because we are still dealing with the prudish dietary mores that insist there’s something sinful and unforgivable about consuming juicy, fatty, delicious animal flesh.
I am starting to see that the need for my book is much, much greater than I had any appreciation for.
Disclaimer: Amy Berger, MS, CNS, NTP, is not a physician and Tuit Nutrition, LLC, is not a medical practice. The information contained on this site is not intended to diagnose, treat, cure, or prevent any medical condition and is not to be used as a substitute for the care and guidance of a physician. Links in this post and all others may direct you to amazon.com, where I will receive a small amount of the purchase price of any items you buy through my affiliate links.