Growing evidence that Alzheimer's is primarily a metabolic disease has led some researchers to propose reclassifying it as Type 3 [skipwords]diabetes[/skipwords], according to the Guardian. Such a revelation could have profound implications on the role that the junk food industry plays in causing Alzheimer's.

Today an estimated 35 million people suffer from Alzheimer's disease around the world, and as many as 346 million people suffer from diabetes. Both numbers are expected to rise exponentially over the next several decades — rises that also happen to be correlated with increasing obesity rates. The correlation is so uncanny that many scientists are investigating a causal relationship between all three epidemics, with staggering results.

Type 2 diabetes has already been strongly linked with obesity and diet as well as with dementia and Alzheimer's. For instance, Type 2 sufferers are two to three times more likely to get Alzheimer's than the general population. The link between Alzheimer's and obesity has been studied less, but a growing cacophony of research is filling that gap. For instance, studies have strongly linked midlife obesity to Alzheimer's. Fitness and a better diet have also been linked to a decreased occurrence of dementia.

Now new studies are suggesting a link even more profound: that Alzheimer's may be caused directly by the brain's impaired response to insulin. A 2005 report found that levels of both insulin and insulin-like growth factors in the brains of Alzheimer's patients were lower than normal, with the lowest levels being found in the brain regions most devastated by the disease. Meanwhile, a report released just last year found that an insulin spray helped improve memory skills in people with Alzheimer's.

Insulin has a well-defined role in the brain's chemistry. It helps regulate the transmission of signals between neurons. It's not difficult to begin connecting the dots at this point. A causal relationship between Alzheimer's and the brain's insulin regulation isn't difficult to imagine and detail.

Of course, more research needs to be done to know for sure, but if Alzheimer's and other kinds of dementia are proven to be another form of diabetes, then the obesity epidemic — and the junk food industry that fuels it — could have consequences on public health that are even more profound than previously realized.