Elevated Blood Sugar Shrinks the Brain

Studies have demonstrated that there is a direct correlation between changes in size of the brains memory center, the hippocampus, and declining memory function. So it’s obviously in our great interest to do everything we possibly can to preserve the size of hippocampus, which is to say, prevent hippocampal atrophy.

It has become clear that there is a powerful direct relationship between not only fasting blood sugar, but even average blood sugar, in terms of predicting the rate at which the hippocampus will shrink and therefore memory will decline. In a new report, recently published in the journal Neurology, researchers in Germany evaluated a group of 141 individuals, average age 63 years, with memory testing as well as a specific type of MRI scan of the brain to measure the size of the hippocampus in each participant. At the same time they looked at blood sugar levels as well as  average blood sugar, by assessing a blood test called hemoglobin A1 c.

What these researchers discovered was really quite profound. There was a perfect correlation between having lower blood sugar as well as lower average blood sugar as measured by an A1c test and several markers of brain function. As the authors stated “lower A1c and glucose levels were significantly associated with better scores in delayed recall, learning ability, and memory consolidation.”

They found that the average blood sugar, the A1c “strongly associated with memory performance.” The authors also were able to draw a conclusion between blood sugar and reduction in size of the hippocampus.

The conclusion of the research stated “our results indicate that even in the absence of manifest type II 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. 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.” (italics added)

These researchers have made it very clear that blood sugar levels are dramatically associated with brain function and brain structure. These are findings that have profound implications, especially in the context of the idea that there are absolutely no pharmaceutical interventions available anywhere on the planet that have any meaningful effect on brain structure or brain function.

This type of information is totally supportive of my raison d’être, my reason to be. This research completely supports the major contention of Grain Brain and that is that sugar and carbohydrates represent a powerful threat to the brain. The take-home message is to cut the carbs, ditch the sugar, and welcome healthful fats back to the table.

  • Eve-Loraine

    Can the damage be reversed?

    • Lynn Dell

      It probably depends on how much damage there is, and there has to be an ability to do aerobic exercise in the individual. I’m sure Dr. Perlmutter would point out this article, which is on the web, that he posted to this site: http://www.drperlmutter.com/study/exercise-training-increases-size-of-hippocampus-and-improves-memory/

      • Eve-Loraine

        Aerobic exercise is difficult for me. I have already had a brain bleed. The right side of my body does not work. My A1c is 5.7. I am now in ketosis and hope to avoid diabetes and memory loss. Thanks for replying.

        • Lynn Dell

          What you said encourages me, not that you had a brain bleed, of course, but the fact that you are working hard at this and are now in ketosis. Congratulations! In fact, at this point in my life I can’t exercise too hard, or I will increase my blood sugars. I can go out on what I call a “zen” walk or bike ride. Btw,, I used to be involved in “stroke” and head trauma rehab, in addition to burn rehab, so my hat is off to you!

          • Eve-Loraine

            Thank you, Lynn. I have been in ketosis about a month. I need to keep the carbs to about 20. I have made a chart which adds the carbs and the fat to give me daily totals of each. I keep the fat to about 30 and the protein to 50 I think. I do intermittent fasting from 7pm to 11.30. I don’t feel hungry. My BMI is 24 so I would like to lose a little more weight but am not classed as overweight. I don’t know how long I can keep this up.
            Most people think I have gone mad. It is so good to have Dr Perlmutter for encouragement.

          • Lynn Dell

            For sure.

        • Lynn Dell

          Here is a search on bdnf (brain derived neurotrophic factor) for this site. DHA also plays a role: http://www.drperlmutter.com/tag/bdnf/

  • Ester gonzalez

    My Dear Doctor…I really apreciatte your issues and all info you share…One petition: May you put subtittles in spanish in your videos? For a better comprehension and guide,tnanks a lot and blessings.

  • Silvia Regina

    Thanks very much Dr. David, I can now watch all your videos with full compreension!

  • Lynn Dell

    This may not be my raison d’etre, but it is the central organizing principle around which I’m building personal lifestyle choices.

    To keep blood sugar down means slowing down the formation of advanced glycation end products. These may or may not be involved in the shrinkage of the hippocampus, but to keep blood sugar down also helps the brain’s memory center. To keep blood sugar down means you keep your insulin down, which, in turn, helps you lose needed weight at a more rapid pace. There is something about high insulin levels that make it very difficult to lose weight.

    I wish everybody who is about my age would just take their morning fasting glucose for a while, and if it is over 92 on a consistent basis, consider lowering the carbs and raising the fat levels (the right kind of fat, of course).

    Thank you again, for all your work!

    • MTZ

      How old are you Lynn Dell, and tell us about your diet???

      • Lynn Dell

        Mid fifties. Last year was prediabetic and very overweight. If I follow the grain brain diet my fasting glucose is well below 100. If I don’t, I revert back to prediabetes.

        I recommend the low carb diet of grain brain. I take all the supplements Dr. Perlmutter recommends plus co enzyme q. I only take a little resveratrol now and then. I put a hefty pinch of organic cayenne pepper in a tablespoon of coconut oil each morning because it definitely helps me with digestion and elimination. My husband wishes he could do that but he is sensitive to salycilates in food, also it winds up being medium hot, which not everybody can take. We tend to eat lots of eggs, some avocados, little grass fed hamburger, organic chicken and wild caught fish. Lots of kale and spinach and celery. Hummus, some cheese, and a little heavy cream in coffee. Walnuts, almonds, pecans, cashews, and dark chocolate. Sometimes carrots. We like chipotle bowls every now and then and try to go low on the rice and beans. We like pumpkin seeds, too.

        • Lynn Dell

          Oh yeah, in order to stay on track and not focus so much on food, it is a replacement reward to take glucose readings throughout the day. That encourages me that I’m on the right track, also makes it a challenge to not mess the next one up. I find the webinars, internet reading, hanging around blogs such as this one, also Wheat Belly blog helps me stay focused, in addition to helping with learning. But taking glucose readings is key, in my case.

  • Jan in KW

    Timely missive! It’s unfortunate that our institutions, senior living communities and nursing home all cater to a high carb, sugar laden, low fat diet. This MUST change sooner, rather than later.

    • Inaliain right of self defense

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  • Frank

    Dr Perlmutter Im a diabetic on a
    insulin pump.before reading your book A1c was 7.3 I started on the diet jan 27 My last A1c was 6.1 also lost 40lbs still working to improve my levels, very difficult but Im hanging in there,what would you recommend for a good A1c for me knowing im on the pump

  • Jeff

    Is it true that eating no carbs will produce a soap-like substantce in the body? I heard this sometime ago and I just would like to know if it’s true.
    Thanks a lot!

  • Susan Smith Kercher

    What if you can’t get your BS down? I stay in ketosis with LCHF, but my BS run 115-130 or higher. And my doctor thinks it’s fine. Also, I can’t lose any weight.

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  • Minnie

    Dr Perlmutter
    I am a big fan, even purchased 10 copies of Grain Brain for friends.
    I used organic sprouted corn tortillas by Food for Life. Your glycemic index makes me think I have made the wrong choice. Please help? I bake with xylitor and my mix of organic almond, coconut and golden flax flours, Yum! I try to eat only organic and fresh homemade everything.

    • David Perlmutter

      I am not familiar with that product, but I am hesitant to label any sort of grain or corn-based item like that healthful.

  • My Yoga Video

    “The take-home message is to cut the carbs, ditch the sugar, and welcome healthful fats back to the table.” … Not so fast … by simply eating carbs that include the natural fibrous matrix (lower glycemic index due to fiber matrix of raw veggies and fruits) and eating in moderation, could be enough to stabilize blood sugar. Fats have other issues … large harvests of fruits would only be seasonal for a hunter gatherer …

    • David Perlmutter

      Of course. I advise cutting carbs, not eliminating them entirely. We can still enjoy healthful vegetables and low-sugar fruits.

      • My Yoga Video

        I like your reply in general and I still think that your recommended diet is too high in processed foods. I consider plants that animals eat processed foods and your diet has a high level of animals. Neil Barnard (Power Foods for the Brain)
        is promoting the belief that the mineral concentrations in animal meat is contributing to brain inflamation because animals are an unnaturally high portion of our diet (relative to evolutionary historical levels). What do you think about his summary of research trends? Yes, animals taste good and have high levels of carnitine for a mitochondrial detox and energizing effect. But they also have “unnaturally” high levels of many things including TMAO: https://www.youtube.com/watch?v=x3yp0oTd1YA#t=67.)

  • Laurie

    can anyone tell me why my blood suger is higher since I started this program been on it 4 days

  • Salman Hamid

    Dear Dr. Perlmutter…I am a big fan of your work…There is one child here with cerebral palsy and consequently brain atrophy (shrinking) and epilepsy.
    spastic quadriplegic cerebral palsy.. The child cannot sit and stand… Would you please recommend something for this

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  • It’s a pity that the video refers to a different study to the one cited in the narrative beneath it. I tried to read the study of the 266 participants and found I was reading a different study with 141 participants which was not reporting what you summarise in the video. Any chance you can share the 2012 German study please?

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