In the study, mice showed fewer signs of the disease when given a protein-restricted diet supplemented with specific amino acids every other week for four months, say researchers writing in Aging Cell.
Mice at advanced stages of the disease were put on the new dietary regime, and were found to have improved cognitive abilities over their non-dieting peers when memory was tested using mazes.
In addition, fewer of their neurons contained abnormal levels of damaged tau protein – that is known to accumulate in the brains of Alzheimer's patients, revealed the research team led by Professor Valter Longo from the University of Southern California, USA.
"Although the new study is in mice, it raises the possibility that low protein intake and low IGF-I may … protect from age-dependent neurodegeneration," said Longo, who noted that dietary protein is a major dietary regulator of IGF-1 – a growth hormone known which has been associated with aging and diseases in mice and several diseases in older adults.
“Our findings provide evidence that weekly cycles of a normal diet and a protein restricted diet supplemented with non-essential amino acids regulate circulating levels of IGF-1 and IGFBPs but also reduce tau phosphorylation, and alleviate age-dependent memory deficits in an animal model of AD,” wrote the researchers.
Longo added that his team will now attempt to determine whether humans respond similarly – while simultaneously examining the effects of dietary restrictions on cancer, diabetes and cardiac disease.
"We always try to do things for people who have the problem now," said Longo. "Developing a drug can take 15 years of trials and a billion dollars.”
"Although only clinical trials can determine whether the protein-restricted diet is effective and safe in humans with cognitive impairment, a doctor could read this study today and, if his or her patient did not have any other viable options, could consider introducing the protein restriction cycles in the treatment – understanding that effective interventions in mice may not translate into effective human therapies," he said.