There have been studies that show that profound belief can make you healthier, but sadly not that prayer on ones behalf can.

I speak from experience..I had encephalitis which is a virus in the brain. My husband was told that there was little chance of survival, my parents were called to come and say their goodbyes. My husband asked the people from our church to come and pray over me. Here I am, no after effects of lost memory ect. Somtimes, there is a change, sometimes not when we pray, but I know that even the attitude of prayer quietens our inner self, bringing peace and that must have an effect on our outlook to our situations. I could talk further on this, but not enough space!!!

There is an article on Answerbank answering your question - just click question 7399