As many as 50 million people around the world are affected by dementia, according to Alzheimer's Disease International, an NGO that acts as the federation of Alzheimer's associations around the world. ADI estimates that 131.5 million people will be living with dementia by 2050, while someone develops the condition every three seconds. A survey conducted by ADI shows that two out of every three respondents believe that there is little or no understanding of dementia in their countries.

Dementia is the collective name for progressive brain syndromes that affect memory, cognition, behavior and emotions, and is the leading cause of disability and dependency among elderly people. Although each person experiences dementia in their own way, eventually they will be unable to care for themself and will need help with all aspects of daily life.

There are more than 100 forms of dementia, the best-known being Alzheimer's disease, which accounts for 50 to 60 percent of all cases.

Symptoms may include: loss of memory; difficulty in finding the right words or comprehending speech; difficulty in performing previously routine tasks; and swings in mood and personality.

In Taiwan, 71 percent of people with varying degrees of dementia have reportedly gone missing at least once, while 60 percent of caregivers say the people they look after have trouble working out where they are going, according to research conducted by academics Chen Ni and Zhang Caihua and published in the Journal of Nursing Science.

In Japan, 4.6 million people have dementia. Of them, 12,000 went missing in 2015, a rise of 1,452 from the previous year. While most were found within a week, 479 people died before they were discovered, while a further 150 remain missing, according to an official police report. Every year, as many as 100,000 people in Japan have to quit their jobs to care for a senior family member with dementia.