presenile

adjective
pre·​se·​nile | \ ˌprē-ˈsē-ˌnīl How to pronounce presenile (audio) \

Medical Definition of presenile

1 : of, relating to, occurring in, or being the period immediately preceding the development of senility the presenile period of life presenile depression
2 : prematurely displaying symptoms of senile dementia