That the number of centenarians in Japan — at a record 65,692 as of this month, a figure released every year ahead of Respect for the Aged Day this week — has been and will keep rising comes as positive news and can be attributed to advances in medical technology and services, improvement in living environment and increasing health consciousness that enable people to live longer. That there were only 153 centenarians when the health ministry's annual survey began in 1963, with the number topping 10,000 in 1998, 30,000 in 2007 and 50,000 in 2012, shows how rapidly people's longevity in this country has been extended. The average life expectancy stood at record 87.05 for women (the second-best in the world) and 80.79 for men (fourth-best) last year.

But a society in which people live longer also has its worrying aspects. One is that the number of people with senile dementia will inevitably grow with the rise in the elderly population. The number of senior people with dementia, estimated at 4.62 million in 2012, is forecast to reach 7 million — or 1 out of 5 elderly persons in Japan — in 2025. A Health, Labor and Welfare Ministry estimate shows that there are more than 8 million people with dementia, including those who suffer mild cognitive problems and are believed to carry a high risk of developing the symptom. Senile dementia will soon be a common illness.

The growing problem of senile dementia was one of the key issues discussed at the Group of Seven health ministers' meeting last week in Kobe, where the participants agreed on the need for early diagnosis of patients and improvement in their living conditions. The World Health Organization estimates that the number of dementia patients worldwide will triple from the current 47 million by 2050 given the graying populations of many countries.