Is it because the are old?
Is it because you have grown older?
Is it because they are of no USE to you anymore?
I think the 3rd option is most applicable to human nowadays.
Always remember that without ur parents, you are no one.
I'm not only referring to the parents who brought you into the world.
It's the parents/guardian that brought you up to who you are today.
It's the parents/guardian that gave you food when you were hungry.
It's the parents/guardian that gave you enough education that you became so smart and forgot that your education was because of them.
It's them that you have forgotten when you grow up.
If you have neglected them today. Go home.
Give them a call whenever you can just to ask them if they have eaten.
Brighten their day.