Memory impairments in older mice may be due to a decrease in DNA methylation in the brain, reports a study published online this week in Nature Neuroscience. These findings suggest a potential cause underlying the loss of memory ability that accompanies normal aging.

Methylation is a mark that is added to DNA that affects whether a gene is active or not. Hilmar Bading and colleagues found that older mice had decreased levels of a protein that methylates DNA in the hippocampus, a region of the brain known to be important in creating and storing memories. If they increased the levels of this protein in the brains of older mice, they remembered just as well as younger mice. Decreasing levels of the protein in younger mice left them just as impaired as older mice.