You may have known for several years that being overweight and having Type 2 diabetes can increase the risk of developing Alzheimer’s Disease (AD). Recently, researchers have started talking about another form of diabetes: Type 3 diabetes. And, in all likelihood, this form of diabetes is associated with AD.
What’s Type 3 diabetes?
Type 3 diabetes occurs when neurons are unable to respond to insulin, which is essential for basic tasks, such as memory and learning. Most researchers now believe that insulin deficiency is central to the cognitive decline experienced in AD.
What’s the connection between Alzheimer’s gene, APOE, and insulin?
A new study from Guojun Bu, Ph.D., a Mayo Clinic neuroscientist and Mary Lowell Leary Professor of Medicine, found that the culprit is a variant of the Alzheimer’s gene known as APOE4.
The team found that APOE4, which is present in approximately 20 percent of the general population and more than half of Alzheimer’s cases, is responsible for interrupting how the brain processes insulin.
Evidence from human studies
The hypothesis that AD is Type 3 Diabetes was directly investigated by first examining postmortem cases of advanced AD and determining if the neurodegeneration was associated with significant abnormalities in the expression of genes encoding insulin, insulin-like growth factors (IGF-1 and IGF-2) peptides, their receptors, and downstream signaling mechanisms.
Researchers have concluded that the term ‘Type 3 diabetes’ accurately reflects the fact that AD represents a form of diabetes that selectively involves the brain and has molecular and biochemical features that overlap with both Type 1 Diabetes Mellitus (TDM) and Type 2 Diabetes Mellitus (T2DM).
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