Yes because they start losing certain faculties, especially the sharpness of the senses and the mind. Hence one has to be very patient with them, firm at times, but always caring and kind.
Yes, they can be very unreasonable at times, quite demanding and rigid. That is where the challenge lies. One can try explaining as to a child, addressing their real or unreal concerns. It is at times and with some a taxing process especially as we live in fast forward times. But then it helps us to grow kinder, more patient and compassionate. It is important that they keep engaged meaningfully. So one should help set up some arrangements to keep them engaged. It also helps if they continue to participate in work at home in some way or the other so that they feel their importance. Lastly a little time, a call or sitting together for a meal daily, or over the weekend keeps them jolly as they feel cared.
This is in general. But of course each situation is different and sometimes there is a backlog of strain. In such a case it is best to forgive for grudge holds back both, the parent and the child preventing them from moving towards the future.
Affectionately,
Alok Da