Are memory loss and mood disorders actually diabetes of the brain?

An excerpt from Feed Your Brain Lose Your Belly by Larry McCleary, MD

As diseases, memory loss and mood disorders appear to have very  little in common. But could memory loss (even severe memory loss such as  that which occurs in Alzheimer’s disease) and mood illnesses such as  depression and bipolar disorder, actually be treated much the same as  diabetes?

Recent thought provoking research findings suggest that  this might be the case. They provide a common link suggesting that  insulin plays a central role in each of these conditions and that  addressing related metabolic imbalances in the brain could revolutionize  future medical treatments for all of them.

The most common  dementing disorder is Alzheimer’s disease, which currently affects 5  million Americans and accounts for well over $100 Billion in direct  health care costs. Even though it was first identified over 100 years  ago, there is still no effective treatment today. It doubles in  prevalence every five years after age 65, and 50% of individuals who  reach their 85th birthday are afflicted.

Mood disorders – a major  cause of disability and one of the primary factors in missed days from  work – are essentially no more responsive to modern drug intervention  than they were in the 1950s.

However, if recent scientific  findings are confirmed, this is about to change dramatically. Suzanne  Craft and her associates in Seattle, Washington and Roger McIntyre and  his group in Toronto have literally treated patients with both  conditions as if their brains had diabetes. They provided insulin (the  same hormone injected by diabetics to control blood sugar levels) that  was delivered through a nasal inhaler several times a day.

Doctors  who treat patients with diabetes – a condition that is defined by  specific insulin problems – have also noted a much higher incidence of  memory, thinking and mood disorders in their patients. Since there are  insulin abnormalities in the bodies of diabetics and other overweight  and obese subjects who experience a much higher incidence of these  specific brain problems, it would be no surprise if the same were true  in the brain.

The same insulin processing problems seen in the  brains of those suffering from AD and an array of mood disorders are  also noted in patients who are overweight or diabetic. What is  particularly striking is that identical insulin problems have been  identified in the brains of subjects with Alzheimer’s disease,  depression and bipolar disorder who are otherwise healthy and fit! That  could be the common chemical malfunction that unites these disparate  diseases and might provide a vital clue for a host of future therapies  based on a novel new mechanism of disease.

Currently, treatments  are based on postulated malfunctions in various brain-signaling pathways  (acetylcholine in Alzheimer’s disease and serotonin or norepinephrine  in depressive disorders). New therapeutic options may now be visualized  that are designed to enhance brain metabolism and optimize insulin  function in the brain – foreshadowing a new frontier in how we think  about brain disorders.

Glucose, the primary sugar in our blood,  is what becomes problematic when diabetes develops. However, without  glucose life as we know it would not exist. In overweight diabetics  glucose loses its ability to enter and be processed properly by cells  throughout the body. A similar disturbance occurs in the brains of  patients with Alzheimer’s disease and is associated with changes that  can be detected on sensitive brain scans decades before symptoms such as  memory loss are observed.

The existence and distribution of  these characteristic findings are so typical that they can be used to  predict subsequent deterioration. Neuroscientists have even referred to  this inability of the brain to use glucose as brain starvation. Since  insulin delivered through nasal inhalers easily passes into the brain  without entering the bloodstream, it doesn’t create havoc with blood  sugar control. Once within the brain it is able to correct many of the  associated insulin-signaling abnormalities and improve symptoms such as  memory loss, concentration, focus and depression.

These results  have not been overlooked by drug companies. Numerous studies using  current diabetes medications as therapeutic modalities for an array of  brain disorders are already in progress. Many new drug candidates  designed to enhance the effect of insulin in the brain are also in the  pipeline.

From a purely research and educational perspective,  these observations have stimulated numerous investigations designed to  evaluate the expanding role insulin plays in brain development,  cognitive function, brain aging and recovery from central nervous system  insults such as head trauma, stroke and cancer.

It appears that  the future is now when it comes to the interaction between insulin and  the brain. Insulin is no longer considered to be merely the hormone that  controls blood sugar. It is now known to be intimately involved in  heart disease, hypertension, cholesterol metabolism and inflammation  throughout the body. Its role in brain health is just starting to be  appreciated. When we better understand the diverse effects it has  throughout the brain and body, we will have more effective treatments  for many of the health scourges that plague us today. Insulin pathways  have also been demonstrated to play central roles in the aging process –  another potential field of scientific investigation.

From a more  personal perspective, the proper regulation of insulin is directly  under our control each time we make a lifestyle choice, whether it be  what to eat, how much to eat, whether or not to smoke or to exercise, to  avoid unremitting stress or to burn the candle at both ends. These  decisions have a greater impact on avoiding insulin problems than the  most potent drugs available. We must merely take the time to control the  factors that are most easily influenced – those we make each and every  day – to keep our brains and bodies healthy.

– Larry McCleary is the retired Acting Chief of Neurosurgery at Denver’s Children’s Hospital, and author of Feed Your Brain Lose Your Belly.  He can be reached at his self-titled site, Dr. McCleary.


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