Obese people are already considered to be at a higher risk for developing Alzheimer's but the findings offer some insight into a possible explanation for this trend.
"This is the first indication that modest changes in the normal diet can slow some aspects of Alzheimer's disease," said Caleb Finch, co-author of the study published in the online version of Neurobiology of Aging (doi:10.1016/j.neurobiolaging.2004.09.014).
"But that is far and away yet to be proven for humans," he cautioned.
In the study, researchers at the University of South Florida in Tampa and the University of Southern California used mice whose DNA had been altered with human genes from two families with early onset hereditary Alzheimer's.
The mice were then split into two groups as young adults: one that could eat all it desired and the other that had its food intake reduced by 40 per cent over a four-week period.
The researchers looked at the formation of plaques caused by a build-up of the fibre-like substance called beta-amyloid. Amyloid plaques, deposited in the brain during Alzheimer's disease, accumulate in the hippocampus and frontal cortex of Alzheimer's sufferers - areas responsible for memory.
In the diet-restricted mice, both the amount and size of plaque was about 50 per cent less than in mice that ate as much as they wanted.
"The power of this study is that two different sets of [human] family mutations were equally sensitive to the effect of diet and slowing the Alzheimer's-like change," said Finch.
The next goal is to find out why diet restriction has such profound and rapid effects, he added. Both the reduced blood glucose or the lowered insulin are thought to be potential factors.