New insights into how the human brain responds to chronic pain could eventually lead to improved treatments for patients, researchers say. Chronic pain is common throughout the world. More than 100 million Americans are believed to be affected by chronic pain. "People living with chronic headache and other forms of chronic pain may experience reduced quality of life, as the pain often prevents them from working, amongst other things. It is therefore imperative that we understand the causes of chronic pain, not just attempt to treat the symptoms with medication," the lead author said.