Tag Archives: memory loss

Do High Insulin Levels Cause Memory Loss and Dementia?

dementia, memory loss, Mediterranean diet, low-carb diet, glycemic index, dementia memory loss

Don’t wait to take action until it’s too late

Insulin resistance and high blood insulin levels promote age-related degeneration of the brain, leading to memory loss and dementia according to Robert Krikorian, Ph.D. He’s a professor in the Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati Academic Health Center.  He has an article in a recent issue of Current Psychiatry – Online.

Proper insulin signaling in the brain is important for healthy functioning of our brains’ memory centers.  This signaling breaks down in the setting of insulin resistance and the associated high insulin levels.  Dr. Krikorian makes much of the fact that high insulin levels and insulin resistance are closely tied to obesity.  He writes that:

Waist circumference of ≥100 cm (39 inches) is a sensitive, specific, and independent predictor of hyperinsulinemia for men and women and a stronger predictor than body mass index, waist-to-hip ratio, and other measures of body fat.

Take-Home Points

Dr. Krikorian thinks that dietary approaches to the prevention of dementia are effective yet underutilized.  He mentions reduction of insulin levels by restricting calories or a ketogenic diet: they’ve been linked with improved memory in middle-aged and older adults. His theory is also consistent with the commonly seen association of type 2 diabetes with dementia: overweight and obese type 2’s quite often have high insulin levels, at least in the early years.

Dr. K suggests the following measures to prevent dementia and memory loss:

  • eliminate high-glycemic foods like processed carbohydrates and sweets
  • replace high-glycemic foods with fruits and vegetables (the higher polyphenol intake may help by itself)
  • certain polyphenols, such as those found in berries, may be particularly helpful in improving brain metabolic function
  • keep your waist size under 39 inches (99 cm), or aim for that if you’re higher and overweight

Nearly all popular versions of the paleo diet would qualify as being low glycemic index.

I must mention that many dementia experts, probably most, are not as confident  as Dr. Krikorian that these dietary changes are effective.  I think they are, to a degree.

The Mediterranean diet is high in fruits and vegetables and relatively low-glycemic.  It’s usually mentioned by experts as the diet that may prevent dementia and slow its progression.

Read the full article.

I’ve written before about how blood sugars in the upper normal range are linked to brain degeneration.  Dr. Krikorian’s recommendations would tend to keep blood sugar levels in the lower end of the normal range.

Steve Parker, M.D.

PS: Speaking of dementia and ketogenic, have you ever heard of the Ketogenic Mediterranean Diet?  (Free condensed version here.)

Will Low Normal Blood Sugars Prevent Brain Degeneration?

MRI scan of brain

MRI scan of brain

Our bodies keep blood sugar levels in a fairly narrow range.  You might think you’re fine if you’re anywhere within the defined normal range.

Think again.

Australian researchers found that people with fasting blood sugars toward the upper end of the normal range had more degeneration (atrophy) in parts of the brain called the hippocampus and amygdala, compared to those in the low normal range.  Degeneration in those areas is often manifested as dementia.

The hippocampus is critical for learning and memory formation and retention.  The amygdala is also involved in memory as well as emotion.  The two areas are intimately connected, literally.

How Was the Study Done?

Over 250 study participants aged 60 to 64 years had normal brains at baseline and were free of diabetes and prediabetes.  Nearly all were caucasian.  MRI brain scans were done at baseline and again four years later.  Significant atrophy (shrinkage) was seen in the hippocampus and amygdala over time, with greater atrophy seen in those with higher baseline fasting glucose levels.

Fasting blood sugar was measured only once, at the start, and ranged from 58 to 108 mg/dl (3.2 to 6.0 mmol/l).  (Fasting glucose of 108 would be prediabetes according to the American Diabetes Association, but not by the World Health Organization.)  Participants weren’t tested for deterioration of cognition.

So What?

The results of the study at hand are consistent with others that link higher rates of dementia with diabetes.  Diabetics, even when under treatment, usually have higher average blood sugars than non-diabetics.  The study authors speculate that damage from higher blood sugars may be mediated by inflammation and abnormal blood clotting (prothrombotic factors and platelet activation).

The Mayo Clinic recently reported that diets high in carbohydrates and sugar increase the odds of developing cognitive impairment in the elderly years.

It’s interesting to contemplate whether non-diabetics and diabetics would have less risk of developing dementia if blood sugars could be kept in the lower end of the normal range.  How could you do that?  Possibilities include:

  • avoid sugars and other refined carbohydrates
  • limit all carbohydrates
  • favor low-glycemic-index foods over high-GI
  • regular exercise, which helps maintain insulin sensitivity (insulin is a major blood sugar regulator)
  • avoid overweight and obesity, which helps maintain insulin sensitivity
  • for diabetics: all of the above plus drugs that control blood sugar

Steve Parker, M.D.

Reference:  Cherbuin, Nicolas, et al.  Higher normal fasting plasma glucose is associated with hippocampal atrophy: The PATH Study.  Neurology, September 4, 2012, vol. 79, No. 10, pp: 1,010-1,026.  doi:10.1212/WNL.0b013e31826846de