Some people argue that drug addiction is about poverty and peer pressure. Those do play a role, but at the core of the issue is the biology of the brain. In laboratory experiments, rats will self-administer drugs, continually hitting the delivery lever at the expense of food and drink. The rats aren’t doing that because of finances or social coercion. They’re doing it because the drugs tap into fundamental reward circuitry in their brains. The drugs effectively tell the brain that this decision is better than all the other things it could be doing.
