The number of people with dementia who were reported missing in 2014 was 10,783, up 461 from the previous year, the National Police Agency said Thursday.
Of these, 10,615 people, or 98.4 percent, were found by the end of 2014. The whereabouts of 168 remained unknown.
"We hope to enhance cooperation with related authorities and institutions in order to beef up searches for missing people," an NPA official said.
The agency alerted prefectural police headquarters across the country in June last year to act quickly to trace missing persons with dementia and to treat them appropriately.
But in August 2014, police failed to detect signs of dementia in an 83-year-old man who had wandered off from day care in Yokohama despite police officers questioning him several times in Tokyo. He later died from dehydration in a park.
The NPA began compiling a DNA database of missing persons with dementia in April, using samples from relatives.
Including those who disappeared in 2013 and earlier, 10,848 missing people with dementia were located in 2014. Of these, 6,427 were traced by the police, 3,610 were reported to have returned home and 429 were found to have died. Another 382 cases were dropped after the reports were found to be mistaken.
The police agency said 7,091 people were found on the day relatives contacted police; 10,539 people were tracked down within a week; and 73 people were found more than two years later.