(someone's) aging mind

Translations
стареющий разум (кого-то)
As his aging mind began to forget details, he relied more on notes.
Поскольку его стареющий разум начал забывать детали, он стал больше полагаться на записи.
Definitions
A phrase referring to the mental state or cognitive abilities of a person as they grow older, often implying changes such as memory decline, slower processing, or other age-related cognitive shifts.