Background: On the 26th anniversary of the International Day of Older Persons in 2015 with the slogan "the elderly, advocates of dynamism, growth, and the youth of the population", 12% (900 million individuals) of the world population were above 65 years of age. It is estimated that this rate will reach 22% (2 milliard individuals) by 2050. The purpose of the present study was to dete...