A team of Swedish scientists have found evidence that people with Type 2 diabetes have an increased risk of developing Alzheimer's due to amyloid formation in the pancreas.
According to them, amyloid from the brain can stimulate the growth of fibrils in the pancreas and pancreatic-related amyloid can be found along with brain-related amyloid in human brain senile plaques.
The research sought to uncover how the two diseases are connected by a process called amyloidosis which occurs in both Alzheimer's and diabetes patients.
Amyloidosis is the process by which misfolded proteins accumulate into fibrous deposits that are resistant to degradation.
In the pancreas of type 2 diabetics, amyloid is produced from its precursor, islet amyloid polypeptide (IAPP or amylin), which is a secretory product of insulin-producing beta cells.
This process causes a cascade of body reactions.
As IAPP builds in the pancreas, it kills beta cells, worsening diabetes and pushing along the development of the beta-amyloid deposits.
The investigation focused on understanding how amyloid deposits "seed" or spread within a tissue or from one organ to another.
"Several soluble proteins are amyloid forming in humans. Independent of protein origin, the fibrils produced are morphologically similar," said Gunilla T. Westermark from Uppsala University in Sweden.
In experiments over mice, Westermark was interested in seeing whether the accumulations of IAPP could travel to the brain and from the brain to the pancreas.
IAPP has binding sites in the brain that are suspected to play a role in satiety and emptying of the stomach.
If this is the case, then it might explain where these amyloid deposits come from as well as why Type 2 diabetics are more than twice as likely to develop Alzheimer's.
"It is not clear if IAPP found in the brain is locally produced or derived from pancreatic beta-cells," Westermark said.
In other words, IAPP may have the ability to travel between the pancreas and the brain, building plaques in both.
The study appeared in the American Journal of Pathology.
