The march of time can be unkind to the human body but new research hints at a cause -- and possible solution -- for some of the ailments and decline that often come with age. 

Scientists have long known that cognitive decline as we get older and specific age-related diseases are linked to inflammation, but they are still uncovering precisely why and how this is the case.

Research published in the journal Nature pinpoints the role of a messenger hormone found in much higher levels in older people and mice than their younger counterparts.

When the hormone was blocked in older mice, they were able to perform as well as more youthful rodents in tests of their memory and navigation.

The researchers found that higher levels of the hormone affected the metabolism of immune cells called macrophages, prompting them to store energy rather than consume it. That effectively starved the cells, sending them into a damaging inflammatory hyperdrive associated with age-related cognitive decline and several age-related diseases.

The hormone, prostaglandin E2 (PGE2), "is a major regulator of all types of inflammation, both good and bad, and its effect depends on the receptor that is activated," the study's senior author Katrin Andreasson told AFP. "In this study, we identified the EP2 receptor... as the receptor that leads to energy depletion and maladaptive inflammation," added Andreasson.

They administered to mice two experimental compounds that can block the EP2 receptor and found it reversed the metabolic problems -- restoring their more youthful behaviour and preventing destructive inflammatory activity.