Will my brothers income support stop?

I would like to claim DLA for my brother who has mental health problems and is unable to write due to Arthritis. However, a friend claimed it and then found that her Income Support had been stopped until the outcome of the claim was decided. She was told this was because if the claim was successful Income Support would have to be paying her extra money. I really want to claim for my brother but don't want to put him in the position of losing his Income Support, even temporarily. My brother is in agreement with me doing this.