By Michael A. Keys, MD

Dr. Keys is a geriatric psychiatrist, Adjunct Associate Clinical Professor of Psychiatry at the University of Cincinnati College of Medicine, and Director of The Senior Health Program at the Lindner Center of HOPE, Mason, Ohio.

A couple of years ago, my wife posted her New Year’s resolution on the refrigerator: “Eat less, walk more”.  Turns out to be sage advice in promoting healthy brain aging.  This month we continue with themes about the relationship between general medical health issues and healthy brain aging.  One of the most important health concerns of older adults is subjective change in the memory and the fear of more serious cognitive decline such as Alzheimer’s disease (AD).

First, a bit of back ground on current concepts regarding how we understand cognitive aging.  There has been a shift in research to better understand and define milder forms of memory and other cognitive changes associated with aging.  Mild Cognitive Impairment (MCI) has been proposed as a transitional state between the cognitive changes of normal aging and Alzheimer’s disease.  Neurologist Ron Peterson and his colleagues at the Mayo Clinic have helped define Mild Cognitive Impairment—basically, subjective memory complaints that can be demonstrated by memory tests.  Pre-clinical Alzheimer’s disease, if you will.   These memory issues are less severe and do not impact upon usual everyday functioning.  Beginning in 2004, Peterson and his group recruited 1,786 normal elderly in a county and followed them over time, looking for the earliest signs of memory and cognitive change. What they found was a much higher rate of individuals falling into the MCI group than was previously thought.  Participants in the study developed MCI at a rate of 5.3 percent per year, with a higher rate with advancing age – about 3.5 percent per year for 70-79 year olds and about 7.2 percent per year for 80-89 year olds.  Men were nearly twice as likely to develop MCI as women. And what we know from other studies is that about half the patients with MCI will convert to a diagnosis of Alzheimer’s disease over time.

These findings have highlighted the importance of developing strategies that offset the development and course of Alzheimer’s disease, with the ultimate goal of prevention.  There has been a decided shift in the research community looking at risk factors and associated medical issues like hypertension, elevated cholesterol, heart disease, and diabetes — all issues known to be related to risk of developing dementia in late-life.  Considerable interest has also been focused on diet, exercise, and what we think of as adjustable lifestyle choices.

Dr. Robert Krikorian, neuropsychologist and Director of the Cognitive Disorders Center at the University of Cincinnati Department of Psychiatry, has had a long interest in cognitive aging and the impact of modifiable risk factors such as diet and exercise on brain function.  Dr. Krikorian’s interest has focused on the association of metabolic factors and cognitive decline.

Metabolic syndrome is a cluster of factors that increases the risk of developing cardiovascular disease and diabetes.  It is increasingly common with age and by some estimates affects nearly a quarter of all adults in the United States.  The disorder was first described in the 1950’s and has been variously defined.  Core features include central obesity or elevated waist circumference (your pot belly), elevated triglycerides, reduced HDL (“good”) cholesterol, elevated blood pressure, and elevated fasting insulin. While the physiology is complex, it is apparent that the core feature is insulin resistance, the inefficiency of insulin receptor function that’s crucial for maintaining normal blood sugar levels and getting glucose into cells where it is utilized.  This receptor inefficiency leads to increases in insulin production and circulating levels of insulin, which result in a cascade of physiological changes including damage to blood vessels, increased inflammation throughout the body and brain, and even declining memory function and production of proteins associated with Alzheimer’s disease. These last factors may be the more important in terms of the negative impact of insulin resistance on brain health.

The bottom line is that insulin resistance increases the risk of age-related memory impairment and Alzheimer’s disease.   Dr Krikorian states, “Insulin receptor resistance, and the related excess in insulin production as the body’s attempt to compensate, is one of the fundamental causes of a host of age-related conditions such as increased waist circumference, high blood pressure, high triglycerides, and cognitive decline and dementia.  Insulin resistance is not as well recognized as it might be but is estimated to be a problem for 50% to 60% of the population aged 60 and older in the United States.  It is the precursor to type 2 diabetes.”

Research has shown:

·         Diabetics are more likely to develop dementia than non-diabetics.

·     Elevated insulin levels have been associated with hippocampal atrophy, a  shrinkage of the brain region most important for memory.

·         People in the study who took a combination of insulin and oral anti-diabetes medications had fewer Alzheimer’s-related brain changes then patients taking either medication alone.

·         Oral hypoglycemic agents that improve insulin sensitivity are being studied in Alzheimer’s disease.

The silver lining is that with discipline, the associated effects of metabolic syndrome and insulin resistance is modifiable.  Eating right, eating less, smoking cessation, moderate alcohol consumption, and exercise, all can considerably improve one’s metabolic profile.  Reducing the waistline and building muscle mass are very effective means of improving insulin sensitivity.  Remember, “Eat less, walk more.”

Written by Michael A. Keys, MD

Contributed by and printed with permission from the Lindner Center of Hope