Wikipedia
Gerascophobia is an abnormal or persistent fear of growing old or ageing. Gerascophobia is a clinical phobia generally classified under specific phobias, fears of a single specific panic trigger. Gerascophobia may be based on anxieties of being left alone, without resources and incapable of caring for oneself, Sufferers may be young and healthy.
Symptoms include the fear of the future and the fear of needing to rely on others to do daily functions. Many also fear they will not play an active role in society when they get older.
The term gerascophobia comes from the Greek θα γεράσω, tha geraso, "I am ageing" and φόβος, phobos, "fear". Some authors refer to it as gerontophobia, although this may also refer to the fear of the elderly.