A new study currently published in the journal Neurology further clarifies an association between Type 2 diabetes and Alzheimer’s disease, or other forms of dementia.

To recap this study, which was reported on in detail earlier in Food Consumer, researchers tracked the metabolic performance of 135 men and women from a particular Japanese village for 10-15 years. 

After researching surviving participants, the researchers concluded that those who had type 2 diabetes or some of its symptoms, such as obesity, insulin resistance and high blood pressure, were significantly more likely to develop plaques that distort and deform healthy brain cells.

These plaques are what Dr. Alois Alzheimer discovered in the brain of Auguste D., one of his patients.

Further research has shown that these beta-amyloid plaques are formed through the abnormal clumping of amyloid, a protein manufactured by the body.  These plaques form between nerve cells, and somehow block communication between these nerve cells, disrupting their normal activity and eventually killing them.
 
According to the Alzheimer’s Association, these plaques form in fairly predictable fashion, first appearing the areas of the brain that control learning and memory function, then moving on to other regions of the brain, beginning the slow progression of this cruel disease.

The researchers who participated in the current Japanese study surmise that one possible reason for the association between insulin resistance and Alzheimer’s is that the resulting abundance of insulin and glucose in the blood stream somehow “gums up” the brains ability to flush excess amyloids.

Although this particular body of research verifies prior research showing the diabetes/Alzheimer’s association, other studies have shown that the risk may be greater if diabetes develops during mid-life rather than in later life.

In 2004, research conducted out of Mt. Sinai Medical Center definitively showed that those who had diabetes during mid-life were significantly more likely to Alzheimer’s/dementia three decades later.

Researchers for that study assessed 1,892 patients from a large male cohort; the participants had originally taken part in the Israeli Ischemic Heart Disease Study.  The Alzheimer’s research team discovered that patients who developed diabetes from 1963-1968 were significantly more likely to have had Alzheimer’s thirty years later (1999-2001).

Additionally, a twin study conducted in 2009 and published in Neurology showed that although diabetes does, in fact, increase risk of dementia, the risk is greater if a patient develops diabetes in mid-life than it is among those who develop late-life diabetes.

Specifically, 13,693 twins were studied; of this total, 467 patients had dementia.  262 of them had Alzheimer’s disease, 105 had developed vascular dementia, and 170 had questionable dementia.  1,396 of the participants had diabetes. 

After adjusting for control factors, diabetes was associated with the following odds ratios:  1.89 for dementia, 1.69 for Alzheimer’s, and 2.17 for vascular dementia.

In the abstract, the authors of the study stated, “Diabetes increases the risk of Alzheimer’s disease and vascular dementia.  The risk is stronger when diabetes occurs at mid-life than in late life.  Genetic and early-life environmental factors might contribute to the late life diabetes-dementia association, but could not account for the mid-life diabetes-dementia association.”

For those of us who are in mid-llife and at risk for Type 2 diabetes, the message couldn’t be much clearer.