1) Premature old age 
(se´nil-iz-әm) premature old age.
senile, senilism 1. An aged person; one who exhibits the weakness or diseases of old age. 2. Belonging to, suited for or incident to old age. 3. Forgetful, confused, or otherwise mentally less acute in later life. 4. Occurring in or believed to be characteristic of later life, especially the period after the age of 65 years.