The short answer is YES! However, understanding this connection is a bit more complex and has been poorly understood by the health care community for decades. More recently, a handful of inquisitive researchers and a growing group of doctors are uncovering that the roads to high blood sugar and Alzheimer’s cross paths from beginning to end.
Cognitive decline can occur with or without an Alzheimer’s disease (AD) diagnosis. Without a diagnosis, this condition is typically referred to as dementia. What differentiates the two is the development of protein structures called beta-amyloid plaques and tau proteins. For decades, researchers thought these structures were the cause of Alzheimer’s. Amyloid plaques grow out of control much like cancer and block circulation within the brain, killing brain cells along the way.
However, what cutting-edge researchers now know is that this is an immune response in the brain, not some rogue cellular dysfunction.
They have found that amyloid plaques surround areas of damage or pathogens in the brain as a protective immune mechanism. So this begs the question: What is causing the damage in the first place?
The Common Link – Inflammation
This is where we find a connection to blood sugar. Both diabetes and Alzheimer’s disease are now considered inflammatory diseases. High blood sugar can be the result of inflammation caused by many factors, and inflammation has been shown to precede diabetes. So how is inflammation promoting high blood sugar and cognitive decline, and how is high blood sugar perpetuating the vicious cycle of inflammation in your body and brain?
Blood Sugar in Your Brain
In order for your brain cells to use glucose, they must also have available insulin, a hormone produced by the pancreas. Both glucose and insulin can cross the blood-brain barrier, where insulin must dock on receptors located on cell membranes. That signals the cell that glucose has arrived on site and it is ready to be taken up into the cell for energy production. In the brains of individuals with Alzheimer’s, circulating glucose and insulin are often high, but cells are not able to receive the signals from insulin or free glucose for fuel. This is where high blood sugar and Alzheimer’s meet.
Glucose and Insulin – Best Friends Forever
Your brain loves sugar! In fact, glucose, the final product of carbohydrate digestion, is your brain’s preferred food. While your brain only accounts for 2% of your total body weight, it uses more than 20% of available glucose. So, if your brain loves glucose so much, then shouldn’t more glucose be better? Unfortunately, NO!
Inflammation Leads to Insulin Resistance
Let’s go back to inflammation for a minute. Inflammation is an important immune process that kills pathogens and clears away damaged or infected cells and tissues. Unfortunately, for many people living in Westernized cultures, inflammation is a chronic physical state. Many things can cause inflammation such as stress, environmental pollution and toxins, poor diet, food sensitivities, infections, and obesity. Obesity on its own causes chronic inflammation because overburdened fat cells actually produce inflammatory chemicals that circulate throughout the body causing damage.
Consider that if your brain cells become resistant to insulin, they cannot use glucose for fuel, and they will die. This will generate an immune response and more inflammation because your brain must clear out damaged cells.
Moreover, insulin can actually be anti-inflammatory, but when the body becomes resistant to insulin, the pancreas reduces production. This results in the unregulated production of a pro-inflammatory protein called FOXO1.
Insulin Resistance Causes High Blood Sugar
Regardless of the source, if inflammation becomes chronic, then the insulin receptors on cells can become damaged.
Then insulin cannot dock on the cells and help move glucose from the blood into the cell. That means that after you eat, glucose and insulin stay circulating within the blood instead of doing their jobs within cells. This means you have no energy and high blood sugar and insulin.
Initially, insulin resistance causes the pancreas to make more insulin to respond to increasing blood sugar levels. However, as I said, insulin resistance eventually causes the pancreas to make less insulin leading to even higher blood sugar levels. Then, insulin resistance causes more inflammation, and the cycle continues.
High Blood Sugar Affects Circulation
There are more factors to consider. High blood sugar reduces the production of nitric oxide in the vascular tissues. Nitric oxide is responsible for the flexibility of your arteries, heart, and veins. It allows them to constrict and relax, optimizing blood flow depending on the need for increased or decreased circulation. When nitric oxide decreases, vascular tissue becomes rigid and constricts blood flow leading to high blood pressure.
This puts pressure on the vascular system and can reduce the transport of oxygen and nutrients to cells throughout the body. This means your brain cells receive less oxygen and nutrients as well. Without nutrients and oxygen, neurons die.
You may be starting to see how this cycle is connected and how inflammation is at the root of both high blood sugar and cognitive decline.
A High-Sugar Diet
It is true that a high-sugar diet increases your blood sugar levels. However, before symptoms of diabetes are apparent, the sugar in your diet is setting the stage for a chronic state of inflammation. A diet high in sugar leads to obesity, which increases inflammation because fat cells produce inflammatory chemicals. However, a high-sugar diet, even in the absence of obesity, leads to damage in the intestinal lining, the gut microbiome, and endotoxemia, a condition in which toxins are produced in the blood by dangerous bacterial species. In addition, increased glucose metabolism increases free radical production and therefore metabolism. Refined sugar in the diet is a direct cause of inflammation and therefore increases one’s risk of developing diabetes and Alzheimer’s disease.
Is High Blood Sugar the Only Way to Develop Alzheimer’s Disease?
Leading researchers understand that diabetes and insulin resistance can be one pathway to Alzheimer’s disease. However, there are other inflammatory factors that increase the risk of developing Alzheimer’s by causing or perpetuating chronic inflammation. It is also important to note that genetic factors influencing the brain’s ability to generate and break down beta-amyloid also affect the risk of developing AD. Lifestyle factors, specific exposures, and a host of other conditions can cause damage to the brain and evoke the immune response seen in AD. For these reasons, it is essential to seek care with a doctor that is specially trained to identify root imbalances within your body and help you correct imbalances, reduce inflammation, prevent disease progression, and heal damage.