Diabetes is characterized by high blood sugar levels that result from the body’s inability to produce and/or use insulin. As can be imagined, these increased blood sugar levels have a harmful impact on the whole body, and the brain is no exception.
The human brain is a complex organ, and hence is very sensitive to the harmful effects of high or blood sugar levels, since glucose and oxygen are the main fuel for brain function.
Now diabetes is a double edged sword — both hyperglycemia (or high blood glucose that comes with poorly managed diabetes) as well as hypoglycemia (or low blood glucose that can be caused by diabetes treatment) can negatively impact the brain. For diabetics, chance of brain related complications is just one more reason to keep your diabetes under control.
High levels of blood glucose entering the brain cause damage to blood vessels over time. The brain’s white matter is the area where nerves are linked and communicate in order to carry out every day activities of life. Think of the white matter as the subway of the brain, providing the essential connectivity, and uniting different regions of the brain into networks that perform various mental operations. When excess blood sugar levels damage the small blood vessels of the brain, this connectivity is disrupted and the result is often a dramatic disturbance of normal mental function. Over time, this damage causes changes in thinking, known as vascular cognitive impairment or vascular dementia.
Several scientific research studies have found that the longer you have diabetes, the more of a chance there is of cognitive impairment. A research done at Harvard Medical School, Boston found evidence that “Type 2 diabetes is associated with cortical and subcortical atrophy involving several brain regions. Diminished regional cerebral perfusion and vasoreactivity was found, and this effect is intensified in cases with uncontrolled diabetes”. Both this study as well as another study published in The Official Journal of the American Academy of Neurology found a link between diabetes and cognitive impairment. These studies prove that in older people suffering from Type 2 Diabetes, diabetes-related-inflammation further impairs cerebral vasoregulation, which consequently accelerates decline in executive function and daily activities performance.
Besides cognitive function, diabetes also affects memory and can result in poor reasoning during intellectual tasks.
The Rotterdam Study also links increased serum insulin with decreased cognitive function and dementia.
What is surprising here is that most doctors with a clinical practice treating diabetes everyday find that cognitive impairment is less common in patients with diabetes Type 1, as this kind of diabetes is insulin-dependent and hence, often well-controlled. They find that in general, patients with Type 2 diabetes have developed this condition, because they’re less fit and lead a sedentary, unhealthy lifestyle, which also leads to obesity, heart disease, high cholesterol levels and high blood pressure – all of which can result in inflammation that also damages the blood vessels of the brain.
We’ve discussed that high blood sugar levels can be dangerous to your mental health in the long run, but what about the effects of low blood sugar on brain? For some who try to tightly control Type 2 Diabetes using diabetes medication or insulin therapy, chances of hypoglycemia intensify. For these patients, it is easier to accidentally slip into low blood sugar by simply missing a meal or forgetting to eat a snack. And unfortunately, low blood sugar has more immediate, obvious effects on your brain than high blood sugar.
Low blood sugar levels can impact thinking, mood, cause dizziness, result in poor coordination and can cause nausea, hunger, shakiness, cold or clammy skin, or a pounding heart.
Severe hypoglycemia can result in fainting, seizures or convulsions, and coma. While hypoglycemia is dangerous, it doesn’t have the same long-term lasting effects on cognitive function as hyperglycemia. In fact, a study done at Washington University on rats found that recurrent moderate hypoglycemia preconditioned the brain and markedly limited both the extent of severe hypoglycemia-induced neuronal damage and associated cognitive impairment in these rats. However, impairment of brain function is a recognized consequence of acute hypoglycemia, so don’t ever take low blood glucose levels lightly.
Studies have found that people diagnosed with diabetes in their 50’s are significantly more likely than others to suffer mental decline by their 70’s, which means that diabetes does age your brain faster. Diabetics suffer a 30% larger decline in mental acuity than those without the disease.
Diabetes affects the Central Nervous System (CNS) in a similar way as normal aging does. Researchers found central commonalities between diabetes-induced and age-related CNS changes that prove the theory of advanced brain aging in diabetic patients.
Research does suggest a close association between Diabetes and Alzheimer’s disease as well as Dementia. People with Type 2 Diabetes are more susceptible to developing Alzheimer’s when compared to people their own age who don’t have diabetes. Many experts are now calling this connection as Diabetes Type 3. The link could easily lie in better understanding of IDE or Insulin-degrading enzyme. IDE is a major enzyme responsible for insulin degradation. In addition to insulin, IDE represents a pathophysiological link between type 2. Experts believe that IDE inhibitor may be the future of T2D treatment.
However, inflammation, insulin resistance, and mitochondrial dysfunction are common features in both Alzheimer’s disease and Type 2 Diabetes. Vascular cognitive impairment, which is a possible side effect of diabetes, is another cause of Alzheimer’s. Studies have also linked both Type 2 Diabetes and Alzheimer’s disease to oxidative stress.
By tightly controlling diabetes and working on holistic ways to reverse diabetes via adopting a healthier diet and lifestyle, it is possible to prevent cognitive decline that often comes with poorly managed diabetes. In fact, studies have found that diabetes prevention and glucose control in midlife may protect against late-life cognitive decline, so it’s important to act now!
Don’t be under the impression that if you can control your blood sugar levels today with the help of diabetes medication or insulin therapy, you are protecting your body against further damage. Diabetes related complications worsen over time, and as we have discussed above, the longer you have diabetes, the higher the chances for cognitive decline.
Type 2 diabetes can be primarily controlled and prevented through diet and exercise. Swap out processed foods with whole, fresh food and try the LCHF diet to lose weight. Intermittent fasting along with a LCHF diet is a highly effective method for reversing diabetes. Make sure to eat more of healthy fats to improve your omega-3 to omega-6 ratio. Exercise regularly and meditate to beat stress, and make sure you get adequate high-quality sleep every night. Also, optimize your gut health with probiotics, and try supplements that help to naturally reverse diabetes without any harmful side-effects.
Diabetes and brain aging: Epidemiologic evidence – https://link.springer.com/article/10.1007/s11892-005-0069-1
A look inside the diabetic brain: Contributors to diabetes-induced brain aging – http://www.sciencedirect.com/science/article/pii/S092544390800210X
Global and Regional Effects of Type 2 Diabetes on Brain Tissue Volumes and Cerebral Vasoreactivity – http://care.diabetesjournals.org/content/30/5/1193.short
Increased Risk of Type 2 Diabetes in Alzheimer Disease – http://diabetes.diabetesjournals.org/content/53/2/474.short
Inflammation, Defective Insulin Signaling, and Mitochondrial Dysfunction as Common Molecular Denominators Connecting Type 2 Diabetes to Alzheimer Disease – http://diabetes.diabetesjournals.org/content/63/7/2262.short
Diabetes and Alzheimer Disease, Two Overlapping Pathologies with the Same Background: Oxidative Stress – https://www.hindawi.com/journals/omcl/2015/985845/
Recurrent Moderate Hypoglycemia Ameliorates Brain Damage and Cognitive Dysfunction Induced by Severe Hypoglycemia – http://diabetes.diabetesjournals.org/content/59/4/1055.short
Diabetes in Midlife and Cognitive Change Over 20 Years: A Cohort Study – http://annals.org/aim/article/1983393/diabetes-midlife-cognitive-change-over-20-years-cohort-study
Inflammation-associated declines in cerebral vasoreactivity and cognition in type 2 diabetes – http://www.neurology.org/content/early/2015/07/08/WNL.0000000000001820
Insulin as a bridge between type 2 diabetes and Alzheimer disease – how anti-diabetics could be a solution for dementia – http://journal.frontiersin.org/article/10.3389/fendo.2014.00110/full
Diabetes Mellitus and Risk of Alzheimer Disease and Decline in Cognitive Function – http://jamanetwork.com/journals/jamaneurology/fullarticle/785863
Insulin, insulin-degrading enzyme and amyloid-β peptide in Alzheimer’s disease: review and hypothesis – http://www.sciencedirect.com/science/article/pii/S0197458005000199
Impaired insulin and insulin-like growth factor expression and signaling mechanisms in Alzheimer’s disease – is this type 3 diabetes? – http://content.iospress.com/articles/journal-of-alzheimers-disease/jad00400
Amyloid β-degrading cryptidases: insulin degrading enzyme, neprilysin, and presequence peptidase – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2756532/
Protein misfolding and aggregation in Alzheimer’s disease and Type 2 Diabetes Mellitus – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5193501/