" However, repeating the experiments and expanding on them led the researchers to a different conclusion. While dopamine is involved in motivation or the pleasures of the hunt, that’s not the only way we can feel good. Dopamine is not necessary, it seems, for enjoying sweetness, comfort, satiation, and calmness—research suggests that these pleasures are more strongly linked to the brain’s natural opioids, or heroin-like chemicals, instead of to dopamine. And this has implications for the broader understanding of addiction. "

― Maia Szalavitz , Unbroken Brain: A Revolutionary New Way of Understanding Addiction