You don't have to accept the responsibility, especially if you have reservations.

If you refuse, eventually a court will appoint an attorney to serve as his legal guardian.

I've always found it is best to follow your first decision, especially in complex, difficult matters.

Your brother will be just fine, even if you continue to decline to accept the additional responsibility.

As we age, taking on additional duties and added responsibilities become much more difficult than they might have been 20, 15, or even 10 years earlier.