He who strikes his father or his mother . . . And he who curses his father or his mother shall surely be put to death. (Exodus 21:15 & 17)
When God commands us to honor our fathers and our mothers eight different times in His Word, He means what He says. If we are alive, we are to honor our parents. We owe them our lives. Note that God did not say to honor them if they are honorable. He likewise did not say for us to honor them until a certain age. He simply and clearly commands us to honor them.
I know and I understand that it is often difficult to honor an abusive or neglectful parent. But God never commands us to do what He has not equipped us to do. To honor does not necessarily imply total subjection. It does however call for respect, dignity and esteem. If you have been blessed with loving parents, be thankful and honor them highly. If not, dare to trust God enough to honor your parents despite their character or their age.