A doctor is warning that grain is bad for your brain.

Dr. David Perlmutter is a neurologist and president of the Perlmutter Health Center in Naples, Florida, and he's touting research showing all carbs, including whole grains, are devastating our brains.

In a new book he also claims that Alzheimer's is really a third type of diabetes, and that reveals a link between dementia and diet & lifestyle.

He says we should return to the diet of early man, which consisted of 75 percent fat and protein, and 5% carbs.

Other experts have taken issue with him because they say his recommendation may lead people to load up on unnecessary fat.  

- Rob Archer