Scientists in the United States say they have identified a new protein that may be linked to memory loss in older people.
Researchers from Columbia University in New York say the discovery could lead to treatments to reverse forgetfulness.
The study, published in the journal Science Translational Medicine, said age-related memory loss was a separate condition to Alzheimer's disease.
The Columbia team started by analysing the brains of eight dead people, aged between 22 and 88, who had donated their organ for medical research, the BBC reports.
They found 17 genes whose activity level differed with age. One contained instructions for making a protein called RbAp48, which became less active with time.
Young mice genetically engineered to have low RbAp48 levels performed as poorly as much older mice in memory tests.
Using a virus to boost RbAp48 in older mice appeared to reverse the decline and boosted their memory.