The elderly dementia patient in the next room was unresponsive and in a foul mood, the head nurse warned. Dapper Dan and Beatrice took that information into account and proceeded anyway.

The patient was lying in bed with her eyes wide open and didn’t say a word when the pair launched into a medley of 50s tunes. By the time they got to their third song, “Under the Boardwalk,” they noticed the patient’s toes were moving to the rhythm under the bedsheet and that she was gently tapping her fingers to the music.

It was a subtle move that many singers would have missed. But these performers were trained to look for it.

Dapper Dan is the stage name of Dikki Ellis, and Beatrice is the stage name of Ilene Weiss. They work for Vaudeville Visits, a program at Saint Barnabas Medical Center in Livingston, N.J., which is run by Healthy Humor, a national nonprofit that primarily sends clowns to pediatric units in hospitals.

The performers can be seen prancing down hospital corridors and in hospital rooms, singing, telling jokes, playing musical instruments, laughing, and connecting with patients, their families and staff members.

Healthy Humor’s founders, Deborah Kaufmann, Dina Paul-Parks and Karen McCarty, have more than 60 years of combined experience in health care clowning, mainly in the Big Apple Circus’s Clown Care Unit. When the circus went bankrupt last year, the three pooled their resources and formed Healthy Humor. They recently signed Children’s Hospital in Philadelphia as their 12th client.

They felt it was especially important to maintain the Vaudeville Visits program, which the Big Apple Circus started in 2004, because there are few such programs for patients with dementia. (Meanwhile, under new owners, the Big Apple Circus resumed performances in Damrosch Park at Lincoln Center last week.)

A recent pilot study in the Journal of the American Geriatrics Society reported that clowning reduced moderate to severe behavioral symptoms of dementia. The study involved teams of two clowns working together, going from room to room to visit patients in Toronto’s long-term care geriatric homes.

“We found that after the residents interacted with the clowns for 12 weeks, there was a significant reduction in their neuropsychiatric symptoms,” said Pia Kontos, a scientist at Toronto Rehabilitation Institute and the lead author of the study. “Our study found elder clowns were just as effective as medication in bringing down aggression levels in seniors with dementia.”

She said that the clowns’ wearing vintage outfits likely helped evoke memories for the patients. “I thought, intuitively, this would be pretty magical, and it was.”

Vaudeville Visits is meant for people in geriatric residential care facilities and elders in critical care, and its performers clown around but are not dressed as clowns. Instead, they play iconic characters meant to be easily recognizable to patients, including a cow girl, a used-car salesman and “Melvis” — supposedly Elvis Presley’s brother.

When Ms. Kaufmann made her rounds, she dressed as a bride, often roping in eligible bachelors to play her future husband, and she enlisted women to be her bridesmaids. “Everyone recognizes a bride,” she said. “Working with a partner, we can get the patients to engage, participate and have fun. In one instance, my partner played my mother who tried to marry me off.”

The performers use a mix of song, dance, juggling, puppetry, storytelling techniques and improvisation. “If there are family members or guests visiting, we can ask about things to trigger memories,” Ms. Weiss said.

It was a magic trick that drew a response from one patient. James Chin, 78, who has borderline dementia and was recovering from aphasia following a stroke, sat silently while Mr. Ellis and Ms. Weiss performed Sinatra tunes. After a medley of songs and a few jokes, Mr. Ellis, in his role as Dapper Dan, pulled a red piece of paper out of his pocket, waved it in the air, and transformed it into a rose. As he presented it, Mr. Chin whispered that he used to work as a magician and that he taught others the craft of magic.

The patients with dementia seem to grasp that these characters are there to create fun. “By their dramatic appearance, and their playful invitations, the performers are often able to access forgotten parts of an elder’s past, and coax participation out of residents who normally do not engage or those who have not responded to other activities and interventions,” Ms. Kaufmann explained.

“We make them feel essential,” Mr. Ellis said. He and Ms. Weiss are teammates. They make their rounds twice a month at Saint Barnabas, and work so well together that they’re often asked if they’re married.

“We are, but not to each other,” Ms. Weiss said.

She got one patient, Thomas Guinee, 78, talking by pronouncing his name with a French accent and speaking a few French words. Mr. Guinee responded in perfect French and explained that he was a World War II veteran who fought in France and met his wife there.

Then they asked for musical requests. Mr. Guinee, a Neil Diamond fan, was slightly bothered that none of the young nurses were familiar with Mr. Diamond’s music. After the performers sang “Sweet Caroline” and a number of Mr. Diamond’s songs, Mr. Guinee thanked them for spending time with him and for listening to “a little bit of my story.”

Maria Brilhante, who oversees the Surgical Step Down Unit at Saint Barnabas, which is where patients go after intensive care, said: “A patient may have trouble communicating or not want to cooperate with the staff; then a Vaudeville Visits performer comes in and makes them laugh.”

The performers’ over-the-top manner and corny jokes are effective for people with cognitive decline, said Ruth Drew, director of information and support services at the national Alzheimer’s Association. “Humor can’t be subtle because subtle sarcasm doesn’t work with Alzheimer’s and dementia patients,” she said.

“What makes Vaudeville Visits work is that the program uses humor from the past, something the patients are familiar with,” said Dr. Theresa M. Redling, medical director of the Center for Geriatric Disease and Health Management at Saint Barnabas Medical Center and clinical assistant professor of medicine at Rutgers New Jersey Medical School. She compared it to Reminiscence Therapy, which also involves music, entertainment, discussions and photographs from the past.

“If you go to any adult day program or long-term care facility,” Dr. Redling added, “the music playing is not from today; it’s familiar to the audience. They relate to it, just like vaudeville.”

That was the case with another elderly patient on the dementia spectrum at Saint Barnabas. “He appeared to be sleeping, not focused,” Ms. Weiss described. “We performed a number of songs and when we got to ‘I Got Rhythm,’ this patient belted out the finale, ‘Who could ask for anything more?’”