"Laughter is the best medicine" is more that just a saying, report researchers who've found humor can help fight memory loss experienced by the elderly.

Laughter and a sense of what's funny can reduce the impact of cortisol, a stress hormone that can damage certain brain neurons with a resulting negative effect on learning ability and memory in older people, they say.

In a study led by Loma Linda University of San Diego, Calif., a group of selected seniors, some in good health and some suffering from diabetes, were shown a humorous 20-minute video.

Afterward they were given memory assessments to gauge their recall, memory and sight recognition in comparison to a control group not shown the video.

A measurement of cortisol concentrations found a significant decrease in the groups who watched the video before the assessment, the researchers said.

The most dramatic decreases in levels of cortisol were observed in those seniors with diabetes, they found, while the most significant improvement in memory test scoring was seen in the healthy elderly.

The researchers reported their findings last week at the annual Experimental Biology meeting in San Diego.

"It's simple, the less stress you have the better your memory," psychoneuroimmunology researcher Lee Berk said. "Humor reduces detrimental stress hormones like cortisol that decrease memory hippocampal neurons, lowers your blood pressure, and increases blood flow and your mood state."

The study suggests humor could be a useful addition to health programs aimed at the older population, the researchers said.

"Our research findings offer potential clinical and rehabilitative benefits that can be applied to wellness programs for the elderly," Loma Linda researcher Gurinder Singh Bains said.

"The cognitive components -- learning ability and delayed recall -- become more challenging as we age and are essential to older adults for an improved quality of life: mind, body, and spirit. Although older adults have age-related memory deficits, complimentary, enjoyable, and beneficial humor therapies need to be implemented for these individuals," Bains said.

Laughter and humor also stimulate a release of dopamine and endorphins in our brains, resulting in positive, beneficial neurochemical modifications that can improve the function of our immune systems, the researchers noted.

"So, indeed, laughter is turning out to be not only a good medicine, but also a memory enhancer adding to our quality of life," Berk said.