A diet high in fat and low in carbohydrates could help combat the development of Alzheimer's Disease, a study revealed.

Scientists used mice engineered to suffer from Alzheimer's to test the effects of a high-fat, low-carb diet -- called a "ketogenic diet.”

They found that the brain protein amyloid-beta -- an indicator of the disease -- was reduced in the mice on the ketogenic diet.

The report, published in the journal Nutrition and Metabolism, appears to show the opposite to previous studies suggesting that fat has a negative effect on Alzheimer's.

More than 750,000 people in the U.K. suffer from dementia, with around 55% of these patients having Alzheimer's.

Dementia affects one in 20 people over the age of 65 and one in five over the age of 80, and the number of people with dementia is steadily increasing around the world as populations get older.

The latest study focused on how diet may affect the development of Alzheimer's, finding that a diet high in fat and low in carbohydrates, such as bread and pasta, could play a role in combating the disease.

The team, led by Samuel Henderson from research company Accera Inc in the U.S. along with colleagues in Belgium, said, "This work supports the premise that key aspects of Alzheimer's Disease can be altered by changes in metabolism.

"It also highlights the interaction of dietary components and how such components influence the metabolic state."

The researchers said they believed that insulin and the related hormone insulin-related growth factor-1 (IGF-1) were key players in the link between diet and Alzheimer's.

"Insulin is often considered a storage hormone, since it promotes deposition of fat, but insulin may also work to encourage amyloid-beta production," they concluded.

Journal editor Richard Feinman explained the relationship between the nutrients by suggesting that fat could be seen as the bomb, while insulin from the carbohydrates was the fuse.

"Most studies of the deleterious effects of fat have been done in the presence of high carbohydrate.

"If carbs are high, dietary fat is not oxidised and is instead stored as body fat," he said.

When carbohydrates are very low and fat is high, compounds called ketone bodies are generated in a process called ketosis.

These compounds could play a role in the reduction in amyloid-beta seen in the mice used in the study.

Past research has shown cognitive improvement in patients suffering from mild Alzheimer's who were given a diet to raise ketone bodies.

"Although it is too early to tell how the results will fit into the treatment of Alzheimer's Disease, the implication for diet in general is also important," Feinman said.

"Henderson's effort is one of several recent studies that point the way to understanding metabolism beyond the issues surrounding simple fat reduction."

Professor Clive Ballard, director of research at the Alzheimer's Society, said, "There is considerable evidence from previous studies of mice, rabbits and other animals that high-cholesterol diets increase the amount of amyloid, the main protein in the plaques that form in the brain in people with Alzheimer's Disease.

"Supporting this, obesity and high cholesterol in mid-life have been shown to increase the risk of Alzheimer's Disease in later life.

"Henderson's work therefore contradicts all previous studies.

"If replicated, it will be important to try and identify the reasons for the differences between studies."