In his early 70s, Koji Uchida began to vanish. The first time, the police found him sitting in front of a vending machine 27 kilometers from home.

He began to go missing regularly, once wandering for two days before turning up at a stranger’s apartment, hungry and barely able to remember his name, his mind clouded by dementia.

At a loss for what to do, his family asked the local government to put Uchida under digital surveillance.

In Itami, Hyogo Prefecture, where Uchida’s family lives, more than 1,000 sensors line the streets, each unit emblazoned with a smiling cartoon figure bracketed by Wi-Fi squiggles. When Uchida went out walking, the system recorded his location through a beacon hidden in his wallet and sent his family a steady stream of alerts. When he veered off course, the family could easily find him.

Itami is one of several localities that have turned to electronic tracking as Japan, the world’s grayest nation, confronts an epidemic of dementia. The programs offer the promise of protecting those in cognitive decline while helping them retain some independence, but they have also evoked fears of Orwellian overreach.

Japan’s surveillance efforts presage the conundrums facing countries across the globe as their populations rapidly age: how to manage the huge expense of care for people living ever-longer lives, as well as the social costs to families and other loved ones.