Carl Zimmer (Discover):
[U]nfolding research shows that chronic pain can cause concrete, physiological changes in the brain. After several months of chronic pain, a person’s brain begins to shrink. The longer people suffer, the more gray matter they lose.[...]The Brain A Tiny Key to a Terrible Lock Scientists have traced chronic pain to a defect in one enzyme in a single region of the brain. Could this be a decisive turn in the battle against pain? [...]
To A. Vania Apkarian, a neuroscientist at Northwestern University, the connection between the living memory and the never-ending pain suggests a glitch in the brain. Ordinary pain might turn chronic, he hypothesizes, when inflammation caused by conditions like arthritis or nerve damage provokes an abnormal rush of signals from nociceptors. When these aberrant signals reach the pain network in the brain, Apkarian argues, they overwhelm it. The brain doesn’t get a chance to forget the pain. Instead it learns to feel it continuously. Eventually the neural connections become so strong that we no longer need the original stimuli anymore. The network begins to sustain itself, continually relearning its pain. It can also send signals back down into the body, turning previously painless sensations into painful ones.