Is fasting obligatory for an elderly person who forgets parts of the prayer and chapters of the Quran?

If an elderly person completely loses their mind, the religious obligations of fasting and prayer are waived for them, based on the Prophet's (peace be upon him) saying: "The pen has been lifted from three: from the sleeper until he awakens, from the child until he reaches puberty, and from the insane until he regains his sanity."

However, if their mind is sound and they are capable of fasting, then it is obligatory upon them. If they are permanently unable to fast, then they must pay a fidyah for each day, which is approximately 750 grams of food for the poor.

As for prayer, it is not waived as long as their mind is sound. But if their mind becomes confused and their comprehension is insufficient for performing the prayer, then it is waived for them.