Added sugars hide behind several names including high fructose corn syrup, dextrose, and many others, but it is no secret that these added sweeteners contribute to the increasing obesity epidemic. As our waistlines increase, the rate of type II diabetes has become more and more prevalent and is expanding into more age groups. Although it is well established that added sweeteners bring people out of blood sugar homeostasis, what other effects can we expect as our population grows old with diabetes?
The number of people with Alzheimer’s and dementia is at an all time high with Alzheimer’s currently the 6th leading cause of death in the United States (Alzheimer’s.org). With this growing number, research has looked into a possible link between impaired cognition and unstable blood sugar. It was found that when people have uncontrolled blood sugar, they tend to have bad circulation due to the glycosylation (attachment of glucose to enterocyte) to their small capillaries. This impaired blood flow means a lack of oxygen to certain places in the body that have become too glycosylated (Jakes, 2004). Unfortunately, this is exactly the case in the brain with people who have cognitive disorders. The impaired blood flow caused by diabetes affects parts of the brain that are responsible for memory and function. Recent studies have found a correlation between insulin resistance and cognitive disorders, like Alzheimer’s disease and dementia, leading to further questions about how our diet affects our brains (Iowa State University). When the hippocampus, which controls long-term memory and skills to perform tasks, becomes oxygen deficitient, it can lead to forgetfulness and more extremely, memory loss (Ankawa, 2016).
Insulin resistance is caused by the excess inflammation commonly found with obesity, which disrupts the binding of insulin to cells that allows blood glucose to enter the cell to be used for energy. Although not all regions of the brain are insulin-dependent, the hippocampus does require insulin and is highly dependent on glucose for proper function. Because of this, insulin resistance disrupts the proper binding of insulin to the hippocampal cells and glucose cannot enter the cell to provide energy (Ankawa, 2016). This is what causes impaired blood flow, and therefore brain malfunction, in those with insulin resistance.
Those who are not insulin resistant, but have hyperglycemia, such the case with uncontrolled type I diabetics, are also showing to have problems with memory. The University of Albany did a study that showed that exogenous insulin (insulin shots) improved the memory of patients with hyperglycemia (2016). This highlights the importance of stable blood sugar for diabetics and non-diabetics alike.
A meta-analysis showed a positive correlation between Alzheimer’s disease, obesity, and type II diabetes (Perfenno et al, 2010). Because inflammation is caused by obesity that can lead to insulin resistance, this is no surprise. In a study done by the University of Wisconsin-Madison, that looked at brain scans of people at risk of Alzheimer’s disease, found that those who had more severe insulin resistance had more severe circulation problems in certain areas of the brain than those who had less of an issue with insulin resistance (Iowa State University, 2015).
As more of the population grows old, it is vitally important in our field to understand who is at risk for diet-related diseases and why. As new research surfaces between blood sugar and the brain, it will hopefully be able to assist us (as future nutrition professionals) to help people eat their way to a healthy life.