It’s already known that newly in love individuals show activity in dopamine-rich areas when they view images of or think about their significant others. This means the Ventral Tegmental Area (VTA), which is part of the reward center, shows a lot of activity. (This is also the area that lights up on the brain scans of addicts when they take cocaine.) And sure enough, in scans of couple still moony after two decades, there it is again.

But, unlike those who are newly in love, the long-in-love brains show no activity among the areas that are commonly associated with anxiety and fear. “Individuals in long-term relationships may experience the excitement, sexual attraction, engagement, and intensity associated with romantic love,” says Acevedo. “But they report pining, anxiety, intrusive thinking far less than individuals newly in love.”

The brain scans echo this. In fact, they show not jsut the absence of anxiety, but its opposite. “Interestingly, we found activation of opiate-rich sites, such as the posterior globus pallidus,” says Acevedo. “These sites are associated with pleasure and pain relief. They are also activated by primary rewards such as food, and substances such as morphine.”