http://www.upi.com/Health_News/2009/10/21/Study-High-protein-diet-may-shrink-brain/UPI-76601256104625/ 
NEW YORK, Oct. 21 (UPI) -- U.S., Canadian and British researchers found a high-protein diet may shrink the brain, a phenomenon linked to Alzheimer's disease.
Lead author Sam Gandy, a professor at The Mount Sinai School of Medicine and a neurologist at the James J. Peters Veterans Affairs Medical Center in New York, and colleagues tested four differing menus on mice bred to develop Alzheimer's disease. The mice were fed either a regular diet, a high-fat/low-carbohydrate custom diet, a high-protein/low-carb version or a high-carbohydrate/low-fat option.
The researchers then looked at the brain and body weight of the mice, as well as plaque buildup and differences in the structure of several brain regions involved with Alzheimer's disease. Gandy said the researchers unexpectedly found mice fed a high-protein/low-carbohydrate diet had brains 5 percent lighter than all the others and regions of their hippocampus -- involved with memory -- were less developed.
Until researchers test this effect on mice not bred to develop Alzheimer's disease, it is unclear whether the loss of brain mass is associated with Alzheimer's disease-type plaque. However, studies in the published literature led the authors to develop a tentative theory that a high-protein diet may leave neurones more vulnerable to Alzheimer's disease plaque.
"Given the previously reported association of high-protein diet with aging-related neurotoxicity, one wonders whether particular diets, if ingested at particular ages, might increase susceptibility to incidence or progression of Alzheimer's disease," Gandy said in a statement.
The study is published in the journal Molecular Neurodegeneration.
