Growing old or growing dumb

I was scolded and shouted rudely by my brother tonight.
I was scolded and shouted rudely and bullied at work.
But i could not effectively argue back to defend myself.

I wonder if this is a sign of growing old, getting tired of responding; or growing dumb, lacking the ability to think and respond. Or both.

This discourages me from living, dealing with even the smallest thing in life.