Gerontology is just study of old age. That means it encompasses things related with old age. It is not a specific disease. Those who do gerontological studies specially focus on the treatment and management thereof.
Every one stays to his sixties ,seventies, eighties etc have their own special issues related to health and life style because however healthy a person continues, age has some wear and tear or slow withering of the body tissues and slowing down of various faculties.
But there will be difference in each individual regarding the speed, intensity and the more proneness of one or other part.
However cautious and alert an elder person is, the refluxes will not be as alert and reacting as that of a 25 year old. The response and reaction to environmental changes also will be different and tolerance to them and resilience will be lesser than that of a youth. Similarly the medicines to be administered and their doses and potency are to be adjusted and in some cases medicines may be avoided . Generally in very advanced ages surgery are also not preferred unless warrant very much.
Gerontology includes study and research and making necessary changes and implementation based on them. Gerontology also researches on how to slow down the process of ageing by activity levels, supplements and understanding the process of ageing.