Richard Lum remembers their faces, the fear in their eyes, the uncertainty that seemed to follow them through the pharmacy where Lum filled prescriptions and dispensed advice.
Their memory loss often seemed to go hand in hand with their illnesses, but sometimes, Lum saw the blank looks among his healthy customers.
Lum, now 71, began noticing that as he eased into the slower pace of retirement, his memory became less sharp, his attention less focused.
For the past eight months, Lum has been a regular at Connie Lynch's weekly "Mind Works" class offered at the El Cerrito Senior Center.
There, Lum and others try to solve logic puzzles, sort differently colored and sized tiles, and play word games, figuring that like any other muscle, the brain needs a workout to stay healthy.
"Baby boomers are very concerned," Lynch says.
The old memories remain, deeply entrenched and engraved on our brain cells.
But once we pass age 40, a light fog seems to descend upon us.
"Old age is not an excuse," Lynch says.
Research is proving that those who make an effort to exercise their brains and their bodies are strengthening their memories as well as improving their overall health and well-being.
Dr. Jen Tellier, a neuropsychologist at John Muir Medical Center in Walnut Creek, said a researcher working with rats exposed the critters to stimulating environments.
The brain is a complex and fascinating organ, says Susan Colligan, clinical director of neuropsychology, brain injury and research for John Muir/Mt.
But as we age, the newer memories are apt to be less certain.
It is when those ingrained memories start to waver that patients -- and their doctors -- become concerned.
If you believe there is something more than just a little normal fog creeping into your life, see your doctor about it.