Skin ointments to relieve chronic itching often ease – but don’t completely stifle – the urge to scratch. Now scientists think they know why. Researchers at Wake Forest University Baptist Medical Center in North Carolina used magnetic resonance imaging to look at the brain activity of 13 healthy volunteers while they were scratched on a lower leg with a small brush. The study, published in the Journal of Investigative Dermatology, found that scratching muted activity in parts of the brain associated with unpleasant emotions and memories. That means scratching may suppress the emotional connection to the itch – even if it’s not addressing the cause. “The skin sends messages to the brain, and the brain sends them back. It’s one of those marriages of body and mind,” says lead author Gil Yosipovitch. “You need to target the neuro system, not just the skin.” The study also showed increased activity in other parts of the brain, such as the prefrontal cortex, which is linked to compulsive behavior. That might explain why, once people start scratching, they can find it hard to stop.