Addiction specialist Sally Marlow examines the science behind addiction to find out why so many people in Britain are hooked on drugs and alcohol. Neuroscientists now have a sophisticated understanding of the networks in the brain that can pull a person towards addiction and hold them there. Changes in the brain also help to explain why it can be so incredibly hard to quit. But brains don't act in isolation, and neuroscience doesn't explain everything. Why do some people get hooked in the first place while others, who use drugs recreationally, do not? How much of addiction is genetic, and how much does free will play a role? What about our social environments and life experiences? Addiction specialists have a good understanding of the complex web of factors that drive people towards addiction and know which treatments work. So why are addiction rates for many drugs at an all-time high? Does society even want to find the answers? Sally talks to some of the scientists who wrestle with these questions and to Mel, John, Lavinia and Kevin who reflect on their own experiences of addiction and recovery. Producer: Beth Eastwood First broadcast on Tuesday 24 September, 2019.