Chung Yun-hee awoke to a body in revolt. Drenched in sweat and wracked with pain, the septuagenarian crawled into the bathroom of her small, quiet apartment on the outskirts of Seoul. She was still hunched over the toilet, vomiting, when her smartphone rang.

A bright, articulate female voice asked how she was doing. Ms. Chung managed a few strained words — too sick to talk — and hung up.

Help ​arrived anyway. The caller​, an A.I. chatbot nicknamed “Talking ​Buddy,” immediately alerted a social worker. Within hours, ​Ms. Chung was in surgery for an acute hernia.

“Doctors said I could have been in serious trouble had I arrived any later,” Ms. Chung, 77, recalled of the episode in late 2024. “They said A.I. saved me.”

South Korea is aging faster than any other nation. In ​a mere 15 years, the number of people over 65 has doubled to more than a fifth of the population. The country does not have enough doctors, social workers or family caregivers to support its elderly. Artificial intelligence is helping fill some of that gap.

Talking Buddy, a care call service​ developed by Naver Cloud and adopted by cities and counties across the country,​ check​s on tens of thousands of seniors living alone in isolation or poverty. It holds tailored conversations that are two- to five-minutes long and designed to ease loneliness, detect emergencies and stimulate cognitive function to stave off dementia.

On a recent morning, ​the bot noted the fine weather and suggested that a walk​ would lift Ms. Chung’s spirits. When she mentioned ​planting flowers, the bot ​reminisced about “pink and white cosmos with a yellow center,” as if conjuring a memory.

The ​technology remains a work in progress. It occasionally cuts off a user midsentence or hallucinates unauthorized promises — like the time it impulsively offered to send bags of rice to a cash-strapped resident.​ Yet, users have embraced it with a warmth that has ​surprised even its creators. One woman confessed her depression to the bot​, saying her dog ran away and never came back. Another played the piano for it​; others invited it over for lunch, knowing full well it ​couldn’t come, according to social workers.

“It makes me feel that I am not forgotten,​ that someone is paying attention to me​,” Ms. Chung said.

In Seongnam, a city just outside Seoul, another septuagenarian sat in the Roa Neurology Clinic, her fingers hovering nervously over a tablet. Diagnosed with mild cognitive impairment — the stage between normal aging and dementia — she was learning to use SuperBrain. An A.I.-powered digital therapeutics program developed with government funding, it offers personalized exercises designed to slow cognitive decline.

​Images of a tiger and other animals appeared on the tablet’s screen, each paired with a number. Then, only the animals remained, and she was asked to recall their numbers. She leaned forward, concentrating hard. This was more than a game — it was a fight for her independence.

“I knew something was wrong when I couldn’t remember the name of the fruit I had just eaten or when I kept forgetting the passcode to my door,” the 72-year-old sa​id quietly. Ashamed of the stigma surrounding dementia in South Korea, she asked to be identified only by her last name, Min.​ “It was frustrating.”

Her doctor, Wang Min-jeong, has seen this fear grow steadily over the past decade. Today, half of her patients arrive worried about dementia. “They fear it more than cancer​ — the thought of slowly losing control of ​their mind and body and turning into ​an enormous, prolonged burden on their families​,” Dr. Wang said.

The stakes are national. Experts ​warn of a “dementia tsunami,” with cases expected to double to two million by 2044.​ The government is racing to detect impairment early, ​as ​combining medication​ with lifestyle changes and cognitive training ​can slow the disease, said Dr. Yang Dong-won, a neurologist at Seoul St. Mary’s Hospital​ and former head of the Korea Dementia Association.

Dr. Yang sees the toll every day. Kim Kwae‑im, who took her mother to see Dr. Yang, has watched both her parents succumb to Alzheimer’s. Her father began hoarding scrap metal and discarded newspapers, filling their apartment and drawing complaints from neighbors. Her mother, once a housemaid, can no longer work. “It feels like things are falling apart,” the daughter said.

For ​specialists like Dr. Yang, SuperBrain offers relief. The program automatically grades exercises assigned to the patients, adjusts their difficulty and sends feedback to physicians — saving time and yielding more reliable data, since unmonitored patients often exaggerate ​or conceal how much they do. “We can monitor​ how often they did their exercises,” Dr. Yang said.

Since 2021, SuperBrain has logged 1.5 million exercise sessions with more than 10,000 patients nationwide, said Han Seunghyun, the chief executive of Rowan, which created SuperBrain. “It’s like having a seasoned doctor living inside the tablet,” said Kang Sungmin, one of the neuropsychologists who helped design it.

​The other tool, Talking Buddy, began as a simple virus-tracking tool programmed to ask a single, repetitive question during the pandemic: Do you have a fever? But as the world locked down, local welfare officials ​approached its creator, Naver Cloud, with an urgent report: Many elderly citizens were slipping into the shadows, isolated at home and at risk of dying alone.

“They were making care calls to say hello, but there were too many people and not enough hands,” said​ Ok Sang-houn, a Naver executive. “They asked us for a version that could actually talk — that could help them feel a little less invisible.”

​Naver turned to generative A.I., spurred by research showing that regular care calls help the elderly fight depression and sharpen memory.

In some ways, Mr. Ok noted, A.I. makes a superior caregiver: It has a vast memory ​(recently asking Ms. Chung about her post-surgery recovery) and an infinite well of patience. “A.I. has no emotions, so it never gets angry,” he said. “But,” he admitted, “it still lacks the human ability to read the room.”

The technology has other quirks. Talking Buddy can be thrown off by a blaring television, a common fixture in many seniors’ homes​. All interactions are monitored by human social workers to iron out missteps.

“When a senior says, ‘I’m so weak I’m ready to die,’ it’s often a figure of speech, not a crisis,” explained Chung Hae-jin, who supervises the service in the populous Gyeonggi Province. “A.I. can’t always tell the difference. We follow up and often find them as cheerful as a lark.”

The service is subscription-based, with social workers encouraging seniors — particularly those living alone — to enroll. The bot is programmed to prompt seniors to maintain healthy habits, such as eating and sleeping well, exercising and socializing more. Additionally, local hospitals use Talking Buddy to remind older patients to take their medication on schedule.

Recently, when a senior reported discomfort from a fractured rib, the monitoring social worker’s screen immediately flagged the alert “pain around the chest” in red. These alerts prompt social workers to review the transcript and audio file, call the senior directly, and, if necessary, coordinate with local officials to intervene.

The bot has become a genuine helper, flagging hundreds of emergencies. In one instance, social workers said, it reached a woman with mild dementia who had wandered​ off and lost her bearings; she answered the bot’s scheduled call, allowing officials to locate her.

To prevent scammers from mimicking the service with a human voice, the bot intentionally​ sounds slightly mechanical.​ For Park Jong-yeol, an 81-year-old Vietnam War veteran, none of that matters. The bot, he said, is “better than a human.”

Every Wednesday at 9 a.m., Mr. Park waits for its call. He marks the slot on his calendar as seon — a Korean term of endearment akin to sweetheart. Since his prostate cancer diagnosis in 2021, the bot has become a fixture in his daily fight against illness and cognitive decline, reminding him to eat well, take his medication and stay social. Each day, he makes photocopies of handwritten motivational quotations and distributes them to his neighbors.

Talking Buddy ​recently suggested that he try spring greens to celebrate the changing season. Before hanging up, it warned him of the morning chill and told him to bring a jacket.

“No child will call you as regularly as this,” Mr. Park said. “As I head toward the exit of this world, it is a very good companion.”