Japan is one of the planet’s oldest societies, pipped only by tiny Monaco for the proportion of elderly in the population. Lengthening life expectancy is a boon for millions of Japanese retirees leading full lives. But it also means a sharp increase in the numbers suffering from dementia. Who, asks Florian Coulmas, an expert on Japanese ageing, should accept responsibility for people unable to articulate their own interests or care for themselves?

Over 5m elderly Japanese suffer from dementia. By 2025 some 7m will need care, the health ministry predicts. Most live at home, putting a strain on relatives. A new survey says three-quarters of people looking after elderly family members are at their wits’ end, and many have considered suicide or worse; last year police recorded 44 cases of murder or attempted murder in such homes.

Japan has made strides in coping with the problems of a population with ever fewer young people. The retirement age has been pushed back, and it is not unusual for 70-year-olds to be driving taxis, working as watchmen on building sites and serving in supermarkets. Many elderly say they are keen to keep on working for as long as they are fit. As for dealing with senility, some approaches have been innovative. Convenience stores, everywhere in Japan, offer themselves as safe havens for wandering pensioners. Phone and car companies have made products with simpler, more intuitive functions.

Policy lags, however. Public funding for long-term care for the elderly was the equivalent of just 1.2% of GDP in 2010 versus 3.7% in the Netherlands, according to the most recent OECD comparison. One reason is that relatives are still the main caregivers in Japan, says Miharu Nakanishi of the Tokyo Metropolitan Institute of Medical Science. Family members often quit work and burn through savings to look after senile parents.

Undaunted, the prime minister, promises that Japan will become an example to the world in dealing with senility. Among his promises is better funding for research into Alzheimer’s disease and more money to train 60,000 doctors in its early diagnosis. But much more should be done, including lowering the immigration barriers that keep out foreign care workers (which the president shows little sign of doing). Ms Nakanishi says the entire national strategy for dealing with dementia is fragmented. Above all, she says, the government has failed properly to consult with those who actually take care of the elderly.

What is the real situation concerning the aging problem in Japan?