Connection Between Diabetes and Alzheimer's Disease?

Over the past week in my neurochemistry class, we explored and discussed a very interesting new discovery in the pathogenesis of Alzheimer’s disease. It has been discovered that type 2 diabetes mellitus is a significant risk factor for Alzheimer’s disease. Insulin resistance and glucose metabolism of patients with diabetes mellitus are the two main implications for developing this neurodegenerative disease. Personally, I found the article that we read to be very interesting and was amazed by the fact that two unrelated diseases in terms of pathogenesis can actually be interrelated and have connections with one another. Even after reading the article and discussing the topic for a week, I still don’t quite understand everything, so I will stick to the basics when describing this topic to you.

In order to understand the connection between type 2 diabetes mellitus and Alzheimer’s disease, it is first important to know the characteristics of each disease. Alzheimer’s disease is a neurological disorder characterized by profound memory loss and dementia. The pathological hallmarks of Alzheimer’s disease include a few obscure scientific terms such as, amyloid plaques, neurofibrillary tangles, and amyloidal angiopathy. Loss of neurons and synapses in the central nervous system is also observed in patients with this disease. Types 2 diabetes mellitus is characterized by excessive amounts of glucose in the blood primarily because they are insulin resistant or are insulin deficient.
Like I mentioned earlier, type 2 diabetes mellitus is a significant risk factor for developing Alzheimer’s disease. It has been determined that insulin has important outcomes on brain functions in addition to numerous peripheral metabolic effects. There are two models that describe the connection between diabetes and Alzheimer’s disease. They include central insulin resistance and inflammation in the brain. Both of the models influence insulin sensitivity in the brain, which leads to B-amyloid accumulation and eventually to Alzheimer’s disease.
Insulin is primarily synthesized in the pancreas and has very important roles in metabolic homeostasis. There is evidence that insulin is also produced in the brain. It has important effects in the central nervous system, regulating key processes such as energy homeostasis, neuronal survival, as well as learning and memory. In patients with type 2 diabetes mellitus, the transport of insulin into the brain is reduced, which in turn decrease brain levels of insulin. Studies have linked the reduction of insulin in the brain with Alzheimer’s disease suggesting that the brain must be influenced by insulin levels and sensitivity. Another interesting aspect of the connection between diabetes and Alzheimer’s disease is the implication of glucose metabolism in Alzheimer’s disease. Utilization of glucose by the brain as a source of energy is important for many of the processes that the brain carries out. Abnormalities in the brain of Alzheimer’s patients are connected with alterations in brain metabolism. These alterations are often associated with impaired glucose utilization and energy metabolism, which are two features of type 2 diabetes mellitus.
I have never heard that type 2 diabetes mellitus is a significant risk factor for developing Alzheimer’s disease, so it was very interesting learning about the many factors that play a role in the connection between these two diseases. Learning about this connection has made me more aware and conscious of the decisions I make regarding how much and what types of food I consume.