The Brain-Body Separation Myth, Autism: A Systemic Disorder that Affects the Brain, The Blood-Sugar and Alzheimer’s Disease Connection

The Brain-Body Separation Myth: Your brain is protected from your body

Many doctors and patients view the blood-brain barrier as an impenetrable wall that protects the brain from any problems in any of the other organs or anything that circulates throughout the bloodstream.  However, we now know that the blood-brain barrier is just a partial barrier, not a complete barrier.  The blood-brain barrier is actually a very thin (one cell thick) layer of epithelial cells that protects the brain from potentially harmful agents circulating in the blood.  However, the brain-brain barrier can become “leaky” and the barrier permeable to different substances under many different types of conditions—poor nutrition, stress, infection, digestive imbalances, toxic injury, allergy and systemic inflammation. (1) Just as the gut can become leaky and lead to “leaky gut” syndrome, the blood brain barrier can become leaky.  This is known as “leaky brain”.  This can lead to major problems for the brain, depending on what type of substance is able to penetrate.

The brain, in fact, “reads” what is happening in the rest of the body even under normal conditions of life.  Let’s take a look at autism and Alzheimer’s disease to illustrate the frailty of the myth the brain is walled off from the body.

Autism: A Systemic (Body) Disorder that Affects the Brain

Dr. Martha Herbert is an assistant professor of neurology at Harvard Medical School and the director of TRANSCEND (Treament, Research and Neuroscience Evaluation of Neurodevelopmental Disorders).  She is one of the leading experts in the world on autistic disorders. Her work in autism is considered paradigm-shifting scientific research and thinking.  In her groundbreaking article in Clinical Neuropsychiatry entitled, “Autism: A brain disorder or a disorder that affects the brain?” she explains how the incoherent brain connections found in children with autism which show up as the inability to talk, connect with other people, or produce odd repetitive behaviors, have their root not in the brain but in problems with the digestive system and the immune system.(2)

According to Dr. Herbert, these breakdowns in the body occur because of genetic susceptibilities which are amplified by environmental stresses, exposures and toxins.

She had the foresight to ask the question: “Why do 95 to 100% of autistic children have GI dysfunction and 70% of them have immune system abnormalities?”  After evaluating all the accumulated research on autism she concludes that autism is not a brain disorder, but a systemic disorder that affects the brain.

She believes there may be many “autisms” because each child has unique genetic and environmental factors that can lead to the same symptoms and behaviors.  Dr. Herbert noticed that the brains of autistic children are bigger and appeared swollen.  These swollen brains are filled with activated immune cells and inflammatory molecules that should not be in such a high amounts in young children’s brains.

Where is this inflammation coming from?

She concluded based on her research that it starts outside the brain. She describes autism as a “metabolic encephalopathy” (metabolic disease of the brain).

This is a 180-degree turn from conventional medical thinking in the field of neurology.  If an altered response to a microbe or bug in the body by the immune system can affect brain function, or if a molecule made in the gut can change behavior or perception, then of course the brain is in communication with the rest of the body.  In autism, we can clearly see the effects of systemic imbalances in the body on the brain and cognitive and behavioral abilities.

The Blood-Sugar and Alzheimer’s Disease Connection

Also out of Harvard is the pioneering work of neurologist Dennis Selkoe, who has linked sugar and its ability to create insulin resistance, metabolic syndrome and diabetes to Alzheimer’s disease, which is considered by many experts to be the next epidemic we will see in this country within the next 20-30 years. (3)

Some researchers are calling Alzheimer’s disease “type 3 diabetes” due to recent evidence showing a startling similar relationship between the development of diabetes in the body and the development of Alzheimer’s disease in the brain.  They both arise from the same mechanism: insulin resistance.

Consider the following:

  • People with type 2 diabetes have 4x the risk of developing Alzheimer’s disease than those without diabetes
  • Even people with prediabetes have a higher risk of cognitive decline, poor memory and loss of brain function

This pioneering new research out of Harvard and Brown universities by Dr. Selkoe and Dr. de la Monte has proven that insulin resistance (pre-diabetes) is a major factor in starting the cascade of brain damage that leads to Alzheimer’s disease.  These researchers have shown that the same process that leads to type 2 diabetes in the body (insulin resistance) leads to the development of Alzheimer’s disease in the brain.(4)  Epidemiologists now expect to see an epidemic of Alzheimer’s disease in the near future to follow the epidemic of diabetes and obesity that we are currently experiencing in the U.S.  Who is going to pay for this expected sharp increase in medical costs?

In the next article, we consider the brain as the master organ and discuss how the brain is often overlooked in medicine.  We also look at how little conventional medicine has to offer patients with neurodegenerative disease.


  1. The UltraMind Solution.  Mark Hyman, MD.  Simon and Shuster. 2008
  2. Herbert, M. R. 2005.  Autism, a brain disorder, or a disorder that affects the brain? Clin Neuropsychiatry 2 (6):354-79.
  3. Kinoshita, J.: Alzheimer Research Forum. 2006. Alzheimer Research Forum live discussion: Insulin resistance: a common axis linking Alzheimer’s, depression, and metabolism: J Alzheimers Dis 9 (1):89-93.
  4. Kinoshita, J.: Alzheimer Research Forum. 2006. Alzheimer Research Forum live discussion: Insulin resistance: a common axis linking Alzheimer’s, depression, and metabolism: J Alzheimers Dis 9 (1):89-93.