Hi, I'd like to help you with your question.
It sounds like he might need to talk with a therapist. Brief, supportive therapy can help him learn new coping skills and help address some of the stress he is experiencing with what your parents are going through.
He can start by talking with his doctor for a referral. Doctors often deal with patients with emotional issues and therefore usually have referrals to therapists available. Also, if your brother attends church, he can talk with his pastor either for therapy, or for a referral. Also, he can search on line at http://www.findatherapist.com/
The therapist can do a full evaluation to determine if your brother needs treatment and what kind of treatment is best. If he would need medications, the therapist can help refer him to a psychiatrist. From what you said, it sounds like short term therapy is all he would need.
A book that may help him is called Coping With Your Difficult Older Parent : A Guide for Stressed-Out Children by Grace Lebow, Barbara Kane, and Irwin Lebow. It is available on Amazon.com or his local library may have it available.
I hope this has helped,