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How minor blood sugar spikes and other lifestyle factors impair memory

Kathleen Blanchard's picture
Exercising to improve memory

Researchers published findings in the journal Neurology this week that suggest even small spikes in blood sugar levels could contribute to memory loss and dementia. The finding is especially important for aging Baby Boomers seeking to stay mentally and physically fit.

Evidence mounts that blood sugar affects memory

The newest study adds to mounting evidence that even without diabetes our memory relies on glucose homeostasis. Keeping our memory intact depends on a variety of lifestyle factors and to some extent, heredity. We can all modify our risks for dementia and Alzheimer's disease by taking cues from recent research that links together. For anyone age 50 to 70 the newest finding might be particularly important. According to this study, memory problems were found when hemoglobin A1C levels - a 'snapshot' of glucose control - rose just slightly.

For the investigation, 141 healthy adults had their hemoglobin A1C level measured that reflects average blood sugar levels over a 3 to 4 month period. All of the adults had glucose levels considered within the normal range, which is 4.5 to 6 percent. The researchers recalled the study participants who were asked to remember 15 words. Those whose blood sugar levels went up just modestly – from 5.0 to 5.6 - had more difficulty remembering the words.

Agnes Floel of Charite University Medicine in Berlin who led the study says there may be a couple of reasons that blood sugar affects memory. "Elevated blood sugar levels damage small and large vessels in the brain, leading to decreased blood and nutrient flow to brain cells.”Anything that blocks blood flow to the brain can lead to memory decline, which is why it’s so important to protect brain health by controlling inflammation that is associated with most all diseases.

Changes in the blood vessels that nourish the brain are also associated with Alzheimer’s disease. If the damage progresses, more inflammation occurs leading to worsening memory and possibly stroke.

Past studies show sugar and memory link

Sugar has been suggested to be toxic to the brain in the past too.

UCLA researchers looked at the effect of a high fructose diet last year in rats. Their results showed binging on sugar can slow learning and impair memory. One of the highlights of the study was that adding omega-3 fatty acids to the diet can help mitigate the damage.

In contrast to the UCLA rat study, no protective effect on memory was found from higher levels of a study of f 2,157 postmenopausal women from higher levels of red blood cell (RBC) docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA).

Rats given a high fructose diet were given flaxseed oil and docosahexaenoic acid (DHA), which was shown to protect the synapses of the brain’s neurons. DHA, the study authors’ note, is not manufactured by the body and has to be supplemented through diet.

Sources of sugar in the Western diet include cane sugar (sucrose) and high-fructose corn syrup, in addition to liquid sweetener.

Carbohydrates that have a high glycemic index metabolize into sugar. Those that are beneficial to keep blood sugar levels steady include whole grains, fruits and vegetables and other high fiber foods that help slow digestion to deliver glucose more slowly to the bloodstream.

Insulin spikes could disrupt memory

Fernando Gomez-Pinilla, a professor of neurosurgery at the David Geffen School of Medicine at UCLA and a professor of integrative biology and physiology in the UCLA College of Letters and Science explained: "Because insulin can penetrate the blood–brain barrier, the hormone may signal neurons to trigger reactions that disrupt learning and cause memory loss,” which ties in with the current finding.

Carbohydrates also linked to dementia

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Another study published last year suggested a high carbohydrate diet could lead to dementia.

Researchers from the Mayo Clinic in Rochester followed 200 study participants for 3-years to find the link.

That study suggested eating a high fat diet with more protein might have a protective effect on memory. The study authors noted it doesn’t mean we should eat a high fat diet. The finding instead lends support to the current study that blood sugar control can help us stay mentally sharp as we age. The study was published in the Journal of Alzheimer’s Disease.

Floel explains the hippocampus in the brain is important for learning and memory and also requires glucose for proper functioning.

In 2008 Dr Scott A. Small, associate professor of neurology in the Sergievsky Center and in the Taub Institute at Columbia University Medical Center and colleagues were also able to show that dysfunction of the hippocampus can interfere with memory even in the absence of any other disease state like diabetes. The study authors also found a relation between high blood sugar and age-related memory decline.

High blood sugar levels might interfere with the glucose to brain transport mechanism.The benefits of eating anti-inflammatory foods that are whole and unprocessed are well documented.

Common causes of memory loss

There are undoubtedly a variety of factors that can contribute to memory loss with aging. Sometimes the cause is never discovered.

Common issues linked to memory decline include:

  • Poor sleep
  • Uncontrolled diabetes
  • Some medications,
  • Anemia
  • Low blood sugar or hypoglycemia
  • Mini-stroke
  • Low zinc levels
  • Low vitamin D
  • Electrolyte imbalance (especially low sodium)
  • Alcohol
  • Narrowing of the carotid arteries

There are many other health conditions that can contribute to memory loss that should be evaluated by your healthcare provider. Cognitive decline is not necessarily a normal part of aging but happens from the cumulative effect of chronic – even low-grade – health conditions.

Healthy lifestyle keeps the brain sharp and the body fit

Dr. Gary Small, director of the UCLA Longevity Center and colleagues found just choosing one healthy lifestyle choice such as not smoking lowers our chances of becoming forgetful with aging by 21 percent. Older adults who practiced two healthy lifestyle interventions – for instance a regular exercise program and switching to a Mediterranean type diet – were 75 less likely to have memory issues, according to their finding.

Keeping blood sugar level in a healthy range consistently could help keep memory intact, which is an important note for Baby Boomers especially; even those without diabetes or pre-diabetes. More studies would be needed to understand the link between even small spikes in blood sugar levels that could destroy small blood vessels in the brain and lead to memory loss. Healthy lifestyle practices throughout life including diet and activity are keys to staying mentally sharp as we age.

"The brain in the age of old: the hippocampal formation is targeted differentially by diseases of late life."

"Omega-3 fatty acids and domain-specific cognitive aging"
Eric M. Ammann, MS, et al.
September 25, 2013


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Excellent article Kathleen!
Thank you.