(AP) — Scientists have found a clue to the cause of age-related memory problems. It’s part of the quest to one day tell if those misplaced car keys are just a senior moment or an early warning of something worse.

Researchers at Columbia University Medical Center examined donated human brains, and found a gene in an important memory region quits working properly in older people. It produces less of a key protein.

Then they adjusted levels of that protein in mice, which become forgetful when they age in much the same way that people do. Lower levels of the protein made healthy young rodents perform worse on memory tasks. But boosting the protein made forgetful old mice as sharp as youngsters again.

The research was reported in the journal Science Translational Medicine.