If you say that an old person is in their ~, you mean that their mind is becoming weaker and that their behaviour is similar to that of a young child.
N-SING
If you say that an old person is in their ~, you mean that their mind is becoming weaker and that their behaviour is similar to that of a young child.
N-SING
Collins COBUILD. Толковый словарь английского языка для изучающих язык Коллинз COBUILD (международная база данных языков Бирмингемского университета) . 2012