For the past several years, high-protein, low-carbohydrate diets, such as the Atkins and South Beach diets, have become increasingly popular weight-loss strategies. The fad surged between 2003 and 2005 after the release of The South Beach Diet: The Delicious, Doctor-Designed, Foolproof Plan for Fast and Healthy Weight Loss. However, recent preliminary research conducted on lab mice revealed a potential link between high-protein, low-carbohydrate regimens and Alzheimer’s disease.

Despite many unanswered questions about the causes of Alzheimer’s, researchers continue to make strides in unlocking mysteries surrounding the devastating disease. Recently, a group of scientists researching the effects of various diets on the brain found that a high-protein, low-carbohydrate food programs may cause brain shrinkage, leading to an increased susceptibility to, or progression of,  Alzheimer’s disease.

The study, led by Dr.Samuel Gandy, a professor at The Mount Sinai School of Medicine, located in Manhattan, was conducted on genetically engineered mice bred for studying Alzheimer’s disease.

“Mice normally never, ever get Alzheimer’s disease and we put in human amyloid genes that have mistakes and mutations into the mice to genetically alter them,” Gandy said, referring to a substance thought to play a role in the disease. “They were carrying a human gene that causes Alzheimer’s pathology.”

The unexpected results revealed that the brains of mice fed a high-protein, low-carbohydrate diet were 5 percent lighter than those of mice fed other diets.

Gandy said initially, researchers were looking for a connection between high-fat diets and the onset or progression of Alzheimer’s disease. However, to their surprise, they found a predominant link between high-protein, low-carbohydrate diets as opposed to diets high in fat.

After studying the brains of the mice fed the high-protein, low-carbohydrate regimen, Gandy said he thinks the diet could lead to a build-up of Alzheimer’s disease plaques within the brain. Plaques and tangles are two abnormal structures within the brain and some experts believe they are the prime suspects in damaging and killing nerve cells. Plaques build up between nerve cells and contain deposits of the protein beta-amyloid. Tangles are twisted fibers of a different protein called tau. Tangles form inside dying cells.  According to Gandy, most people develop some plaques and tangles with age but patients with Alzheimer’s develop far more than the average person.

“The main changes in the structure of the brain during Alzheimer’s are two-fold,” Gandy said. “First, nerve cells are lost because they die. And there is a build-up, both inside and in between nerve cells of gooey clumps of material (amyloid plaques and tangles).”

Plaques and tangles usually form a predictable pattern, beginning in the hippocampus region of the brain, which is responsible for learning and memory. They then spread to other regions of the brain. Many experts hypothesize that plaques and tangles block communication among nerve cells and disrupt activities that cells need to survive.

Researchers believe that the high-protein, low-carbohydrate diet may leave neurons more vulnerable to plaque build-up. The high protein is thought to sensitize the nerve cells to the poisons released by plaques, Gandy said. The study results, published in the journal Molecular Neurodegeneration, indicate preliminary research findings, but in order to know whether a  diet low in carbohydrates and high in protein would have the same effects on the human brain as seen in the genetically engineered mice, Gandy said a “randomized, double blind clinical diet trial” would have to be conducted.

Previous research has shown that Mediterranean-style diets that are low-calorie, low-fat and rich in vegetables, fruits and fish may delay the onset or slow the progression of Alzheimer’s disease.

“There are people who have amyloid [plaque] build up who don’t yet show signs of thinking problems at the time that they die,” Gandy said. “That is why we’ve raised the question of whether part of the explanation of that is that there are substances—maybe in the diet—that sensitize the brain to the poisoning of the plaques and tangles. Maybe the people who have the plaques and tangles and get dementia are on different diets or are encountering something that makes their brains more sensitive than the people who have the plaques and tangles but are still thinking normally.”

As Alzheimer’s diagnosis rates continue to climb, researchers are working to unlock answers about what causes the disease. Although experts believe finding a cure is a long way off, scientists have learned a great deal about Alzheimer’s in the past decade, said Pam Smith, education coordinator for the Rush Alzheimer’s Disease Center at Rush University Medical Center.

Today researchers know the disease, is a progressive and fatal brain disease that destroys brain cells, causing cognitive impairments such as memory loss, thinking impairment and behavioral problems. The disease is the seventh-leading cause of death in the United States, according to the Alzheimer’s Association.

Jessica Kirby, director of Care Navigation Services at the Alzheimer’s Association, said it is important for both Alzheimer’s patients and their caregivers to educate themselves.

“Every 70 seconds someone is diagnosed with Alzheimer’s,” Kirby said. “It is crucial for scientists to be searching for a cure and at the same time, it is important for us to support [Alzheimer’s patients’] caregivers.”

Kirby said the Alzheimer’s Association has a 24-hour help-line for patients and caregivers. Most often, she said, caregivers call when they have reached a crisis point. They reach licensed social workers and counselors are who are able to help determine how to best assist the caller.

“It is so important that people get connected to resources and that they know they are not alone in this,” Kirby said. “We want to encourage people to reach out to any kind of community resource. Too many people try to do this on their own and they don’t need to.”