Diabetes is a known risk factor for Alzheimer's disease (AD). A new study has now provided evidence as to what links Alzheimer's with diabetes. According to researchers, a compound known to be associated with AD is present in high amounts in people diagnosed with diabetes.

Researchers have found that people who have diabetes have increased levels of amyloid beta peptide pathology which is known to occur in people with AD, whereas no such increase was seen in people who didn't have diabetes.

“The results were striking. Because we used diabetes as an instigator of the disease, our study shows – for the first time directly – the link between Alzheimer’s and diabetes," Peter Frederikse, PhD, from University of Medicine and Dentistry of New Jersey (UMDNJ) said, in a statement.

Researchers looked at both brain and retina of the study subjects. According to researchers, testing the retina for the presence of the biomarker will help in predicting the onset of AD.

“Our study examined the retina, which is considered an extension of the brain, and is more accessible for diagnostic exams. Our findings indicate that scientists may be able to follow the onset and progression of Alzheimer’s disease through retinal examination, which could provide a long sought after early-warning sign of the disease," Frederikse added.

They say that the formation of an amyloid beta “oligomer” in the brain and retina explains the classic symptoms of AD. Oligomers when attached to neurons, cause insulin resistance in the brain. This launches a vicious cycle in which diabetes induces oligomer accumulation which makes neurons even more insulin resistant. Insulin is known to play an important role in memory formation.  

“This is exciting. Oligomers are the neurotoxins now regarded as causing Alzheimer’s disease memory loss. What could cause them to appear and buildup in late-onset Alzheimer’s disease has been a mystery, so these new findings with diabetes represent an important step," William Klein, PhD, from Northwestern University said in a statement. 

Alzheimer’s disease Facts and Figures (2011) says that, an estimated 5.4 million people have Alzheimer’s disease that is one out of every eight older American.

Future of Alzheimer's Treatment

The present study not only describes the pathway of AD but also gives other researchers in the field a target to develop treatments for the disease.

“In light of the near epidemic increases in Alzheimer’s disease and diabetes today, developing a physiological model of Alzheimer neuropathology has been an important goal. It allows us to identify a potential biomarker for Alzheimer’s disease and may also make important contributions to Alzheimer drug testing and development," Chinnaswamy Kasinathan, PhD, from University of Medicine and Dentistry of New Jersey (UMDNJ) added.

The study will be published in the Journal of Alzheimer's Disease.