Aging of societies has become a global phenomenon. The proportion of people aged 60 and older will double from 11% in 2006 to 22% in 2050 [1]. This is a particular problem in some developed countries like Japan and South Korea [2]. Increasing population and declining birthrates occur over much shorter periods in developing countries [2]. Thailand's population is aging very rapidly. Its percentage of senior citizens increased from 5% in 1970 to 10% in 2006. It will likely be 30% by 2050 [3]. The population of Bangkok is aging faster than in Thailand's other provinces. The office of the National Economic and Social Development Board reported that in 2008 the proportion of elderly in Bangkok was 10% and in 2020 it will be 21%