A survey of the families of the elderly by the city's Chinese University and Department of Health found an estimated 2 000 people a year suffering from dementia go missing, sometimes for days.
However, only one in four families who lose an elderly relative in the high rise city of 6.9 million report the matter immediately to the police, researchers found.
The study reflects the problems of adequately caring for the elderly in Hong Kong, which has the world's lowest birth-rate at 0.9 children per woman.
Insufficient care for elderly
Hong Kong's men meanwhile live longer than men anywhere in the world with average life expectancy of 79 years while women live for an average of 84.7 years, second only to Japan for longevity.
However, families are often too busy to provide proper care for elderly people, who can often be seen collecting cardboard or tin cans for recycling to earn extra money.
A spokesman for the Chinese University research team said: "We recommend family members report to the police immediately if they confirm that an elderly relative is lost.
"The faster they are able to find the elderly relative the less amount of psychological trauma they will suffer. It is worrying that only one in four affected families currently do this." – (Sapa)
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Dementia
Mind Centre