What Is It? Poem by Jonah Street

The very word has lost all meaning,
A failed exam or a death does not cause it,
The very word is unforgiving,
Leaves you stuck after it has bit.

It is built up in the mind
It won't budge, it won't shift, it will never leave,
It can leave you blind,
You will no longer be able to believe.

When it comes you know,
It becomes part of you,
You will feel at an all time low,
You will be left feeling blue.

It is built in the mind and feasts on any living form it can find,
From it you will be unable to hide,
Affecting the nation,
There is no room for alteration.

What is it?