At the opposite end of the country, in Pembroke Pines, Fla., 87-year-old Marilyn Sumkin uses an app called Join Papa to summon what the company calls “grandchildren on demand.” College students show up for shopping, chores and chit-chat.

Studies have found that loneliness is worse for health than obesity or inactivity, and is as lethal as smoking 15 cigarettes a day. It’s also an epidemic: A recent study from Cigna Corp. found that about half of Americans are lonely. According to a recent Harvard University study, the cost of loneliness for Medicare is $6.7 billion a year.

Many have argued that technology is a cause of this epidemic, isolating us from face-to-face communication with others even as it supercharges our economy. But tech can also be part of the solution, says psychologist (and Wall Street Journal contributor) Susan Pinker, whose book, “The Village Effect: How Face-to-Face Contact Can Make Us Healthier and Happier,” describes the day-to-day interactions that are integral to a long and satisfying life.

All humans need deep connections to friends and family. But, as Dr. Pinker discovered when studying the exceptionally long-lived residents of villages in Sardinia, we also need day-to-day interactions with our weak ties—the neighbors, shopkeepers, librarians and others we regularly say hello to.

Studies of therapeutic robots like Paro, a sensor-laden device disguised as a plush seal, have found that they help the emotional state of some elderly people in aged care facilities. While these technologies are incomplete solutions, “anything that makes life easier for seniors is a boon,” says Dr. Pinker.

Venture capitalists are eager to fund startups in the health tech space, dropping a record $8.1 billion on digital health startups in 2018, compared to $5.7 billion in 2017 and $1.1 billion in 2011, according to venture fund Rock Health.

This wave of funding is in part due to how private insurers in the Medicare Advantage program have more flexibility to pay for supplemental benefits, says Andrew Parker, founder and chief executive of Papa, which currently operates only in Florida. Medicare Advantage is a privately managed form of Medicare that covers about one third of recipients. It has more flexibility in how it spends the funds it gets from the government than the government’s own Medicare program. As of 2019, some Medicare Advantage plans can pay for a wide range of benefits the Department of Health and Human Services calls “primarily health related.” These include housekeeping, fitness trackers, non-medical transportation and even groceries. The rationale is that anything that can lead to reduced use of the healthcare system by promoting health has the potential to pay for itself.

Even Apple is in talks with private insurers to pay for Apple Watches with fall sensors in order to monitor vulnerable seniors. Apple already has partnerships with Aetna and UnitedHealth Group Inc. in which members can earn points toward paying for an Apple Watch if they maintain a healthy lifestyle.

It also helps that the first of America’s 72 million baby boomers hit 65 in 2011, making them the largest and wealthiest generation of seniors in history.

Rent-a-Grandkid

Through Papa, college-age young people can sign up to help seniors by going to the store, doing housework or just hanging out. For these “pals,” Papa works on the same gig-economy model as Uber or Postmates. Ten hours a week of Papa service is covered for members of Humana ’s Medicare Advantage insurance who are in a pilot program in and near Tampa.

Ms. Sumkin’s Papa pals take her on trips to the store since she can no longer drive, and they also help combat her loneliness. Ms. Sumkin says that, aside from occasional visits with her children and grandchildren, her only regular human contact is a bi-weekly stretching class and time with those insurer-provided friends. “They’re all very nice and, you know, I’ll converse with them and find out what they’re doing and studying and so forth,” she says. “It’s for me a very important service.”

Papa schedules pals for seniors based on who is available, charging $17 an hour, $10 of which goes to the pal. For an additional $30 a month, clients can choose their pals.

This kind of consistency in who we have contact with is important, says Dr. Pinker. That Papa doesn’t offer it by default is worrisome, she adds.

Fewer than 10% of Papa’s members asked about having the same pal again, and most typically have at most three pals, says Mr. Parker.

Robo Buddy

ElliQ consists of a tablet, a pair of cameras and a small robot head on a post, capable of basic gestures like leaning in to indicate interest and leaning back to signal disengagement.

Unlike Amazon Alexa or similar voice-activated assistants, ElliQ is capable of spontaneous communication, has a wide variety of responses and behaves unpredictably. Its creators say this is essential to making it feel, if not alive, then at least present. It uses what its creators call cognitive AI to know when to interrupt with a suggestion—“Take your medicine”—and when to stay quiet, such as when a person has a visitor.

“It’s not just the same robotic thing day after day,” says Ms. Karp. “The variety just feels good. It’s like you’re talking to another person.” Ms. Karp’s ElliQ is on loan to her from the company developing it, Intuition Robotics, while they conduct their own trials with potential users.

ElliQ costs $1,500 up front, not including service fee of $35 to $50 a month. Dor Skuler, co-founder and CEO of Intuition Robotics, says his company’s research teams in the Bay Area and Tel Aviv studied the root of loneliness. Using pets as a model, they first thought that dogs and cats alleviate loneliness by giving love and demanding care. “But when we went deeper we discovered it’s a lot to do with the feeling of acknowledgment. They walk into a room and the dog acknowledges their presence. It might just look up and go back to chew its toy, but that feeling is really important to getting recognition and feedback.”

ElliQ recognizes faces, and if you stare at “her” (ElliQ was deliberately given a female voice), she’ll look back at you.

One of the main purposes of ElliQ is to help its owner connect daily to other family members. Through an app, ElliQ will prompt children and grandchildren to start video chats with their relative, send notes and links, and share photos.

ElliQ is undergoing a trial with 100 participants conducted by researchers from Baycrest Health Sciences hospital in Toronto and the University of California San Francisco, at retirement communities in Palo Alto and Toronto, in part to verify that ElliQ alleviates feelings of loneliness. If so, the robot might be eligible for coverage under Medicare Advantage, says Dr. Skuler.

That testing is crucial, says Dr. Pinker. The flood of hormones that are released when we are with other people both helps us understand others’ feelings and kills pain and increases pleasure. “We have very little to no evidence that they are released when someone is communicating with a robot,” she adds.

To whatever extent any of this technology works, paying others to keep our elders company or giving them a robot to accomplish the same raises a profound moral question.

“Think about how before these so-called social robots we had a machine called a television,” says Dr. Pinker. “No one thought it was a replacement for a romantic companion or a grandchild.” Talking robots, she says, are “just a more sophisticated version of that.”