Remember to pump some iron Thomas Barwick/Getty

A hormone released by bones seems to reverse age-related memory loss. The hormone can be boosted by exercise, suggesting that lifting weights might protect the brain from the ravages of old age.

Eric Kandel of Columbia University in New York and colleagues were interested in understanding the mechanisms behind normal age-related memory loss.

To investigate, they measured mRNA levels associated with the expression of 23,000 genes in human brain tissue. Genes use mRNA to tell cells to make products such as proteins – mRNA levels therefore reflect how active a gene was before …