Addiction is a condition in which something that was once pleasurable now feels like something you can't live without. It involves intense longing, loss of control, and continuing to engage with it despite adverse consequences. As people continue with addictive habits or substances, the brain adapts in order to restore a balance between dopamine surges and normal levels of the substance in the brain. This leads to neurons producing less dopamine or reducing the number of dopamine receptors, meaning that individuals need to take larger amounts of medication to achieve a high.
Psychological addiction occurs when cravings for a drug are psychological or emotional. People who are psychologically addicted are overwhelmed by the desire to use a drug and may lie or steal to get it. This has a lot to do with brain chemistry; when we do something pleasant, our brains are programmed to reward us by releasing a neurotransmitter called dopamine. Drug addiction isn't just about illegal drugs; it can also include alcohol, nicotine, sleep and anxiety medications, and other legal substances.
These substances produce a feeling of euphoria by triggering large amounts of dopamine in certain regions of the brain responsible for the sensation of reward. Addiction occurs when the act of consuming a substance takes over these circuits and increases the desire to consume more and more of the substance to achieve the same rewarding effect. Opioids are particularly addictive because they activate powerful reward centers in the brain. They trigger the release of endorphins, which dampen the perception of pain and increase the feeling of pleasure, creating a temporary but powerful feeling of well-being. When this dose wears off, individuals may want to recover those good feelings as soon as possible, which is the first milestone on the road to possible addiction.