Kramnik has been diagnosed with an uncommon form of arthritis, called ankylosing spondylitis. It causes him great physical discomfort while playing. In January 2006, Kramnik announced that he would skip the Corus Chess Tournament in Wijk aan Zee to seek out treatment for his arthritis. He returned from treatment in June 2006, playing in the 37th Chess Olympiad. He scored a +4 result, earning the highest performance rating (2847) of the 1307 participating players.