Alzheimer's: A New Form of Diabetes?
Insulin Problems Linked to Early Stages of Alzheimer's Disease
Nov. 30, 2005 -- Alzheimer's disease may be a new, third type of diabetes
that shares common features of type 1 and type 2 diabetes, according to a new
Researchers found that insulin and the cells that process it in the brain
drop sharply in the early stages of Alzheimer's disease. They also found that
insulin levels continue to decline as the disease progresses and becomes more
"Insulin disappears early and dramatically in Alzheimer's disease. And
many of the unexplained features of Alzheimer's, such as cell death and tangles
in the brain, appear to be linked to abnormalities in insulin signaling. This
demonstrates that the disease is most likely a neuroendocrine disorder, or
another type of diabetes," says researcher Suzanne M. de la Monte,
professor of pathology at Brown Medical School, in a news release.
Alzheimer's Disease Linked to Diabetes
In the study, researchers examined insulin and insulin receptor function in
an area of the brain affected by Alzheimer's disease in brain tissue samples
from people who died at various stages of the disease. They compared them to
those with normal aging.
The results, published in the Journal of Alzheimer's Disease,
showed that insulin levels decreased as the disease progressed.
In addition, researchers found levels of insulin receptors in the brain
decreased with increasing severity of the disease. Low levels of insulin
receptors impair the brain's ability to respond to insulin.
At the most advanced stage of Alzheimer's, the study showed insulin
receptors were 80% lower than in a normal brain.
Researchers say insulin also plays a role in the production of the brain
enzyme acetylcholine. Acetylcholine deficiency is associated with dementia and
"This has important implications for treatment," says de la Monte.
"If you could target the disease early, you could prevent the further loss
of neurons. But you would have to target not just the loss of insulin but the
resistance of its receptors in the brain."