Not all addictions are rooted in abuse or trauma, but I do believe they can all be traced to painful experience. A hurt is at the centre of all addictive behaviours. It is present in the gambler, the Internet addict, the compulsive shopper and the workaholic. The wound may not be as deep and the ache not as excruciating, and it may even be entirely hidden—but it’s there. As we’ll see, the effects of early stress or adverse experiences directly shape both the psychology and the neurobiology of addiction in the brain.