Police were unable to confirm the whereabouts of 168 people with dementia who were reported missing in 2014, the National Police Agency announced Thursday.
Missing persons reports for 10,783 dementia patients were submitted to police across the nation in 2014, showing an increase of 461 people from the previous year.
Police receive missing persons reports on dementia patients from their relatives and others, search for them and enter their physical characteristics, descriptions of their clothing and other information in a database.
Of those who went missing last year, 6,130 were men and 4,653 were women.
By prefecture, Osaka Prefecture topped the list with 1,921.
Among the dementia patients for whom missing persons reports were submitted to police in 2014 or earlier, the whereabouts of 10,848 people were confirmed in 2014.
Police and others found 6,427 of them, while the whereabouts of 3,610 people were ascertained by their returning home and other means. A total of 429 of the missing had died.
The whereabouts of 97.2 per cent of the missing dementia patients were determined within a week. It took more than two years to determine where 73 of the missing were.
The police agency started in 2012 to tally the number of dementia patients who go missing. In 2012, 9,607 missing-persons reports were submitted, and the total number increased to 10,322 in 2013.
As of the end of April 2014, a total of 258 people were still unaccounted for.
The police agency introduced a new system last year in which photos of people with dementia who have been taken into protective custody can be viewed by families and others at police stations and elsewhere. However, the system had photos of only 39 people as of the end of May.
Photos are put into the system at the request of municipalities who taken custody of unidentified people with dementia, but many municipalities reportedly refuse to provide photos to protect people's personal information.
As some people with dementia cannot tell authorities their own names, the police agency urges their families and others to take such identifying measures as writing dementia patients' names on their clothes and shoes.