How does the brain react to a romantic breakup?

—Chelsea Brennan , Minneapolis

Xiaomeng (Mona) Xu, a postdoctoral research fellow at the Warren Alpert Medical School at Brown University and at the Miriam Hospital, responds:

You're in the midst of a breakup and feel like a different person. You find yourself spending a lot of time longing for your ex, constantly checking her Facebook updates, and wondering what went wrong. This shift in patterns of thought and behavior may be caused by neural changes that occur after a breakup.

Neuroimaging studies have found that being rejected, even by a stranger, activates many of the same regions in the brain as when experiencing physical pain. In one study, biological anthropologist Helen Fisher of Rutgers University recruited brave participants who held still in a functional MRI scanner while they looked at pictures of the person who had recently dumped them. These participants exhibited increased brain activity in several regions associated with reward, motivation, addiction and obsessive-compulsive disorder, which helps to explain why you might struggle to let go after a romantic relationship ends.

Grief can also be a part of the breakup process. In another brain-scanning study, researchers asked women who had gone through a recent breakup to think about their ex in an fMRI machine. They found patterns of brain activity consistent with feelings of sadness, rumination and chronic depression.

For some people, heartache can continue months after a split. A team of German investigators, studying a small group of people who were still hung up on an ex up to six months after the relationship had ended, also found brain patterns consistent with depression, such as decreased activity in the insula and the anterior and posterior cingulate cortices.

Although such studies show that heartbreak is associated with obsession and grief, the findings are limited. Our understanding primarily comes from research in which participants are asked to actively think about their ex, something people probably don't do all the time. Additionally, studies tend to be about the heartbroken, rather than the heartbreakers, and focus only on the period of misery postsplit. Luckily for many people, the heartache from a lost relationship fades over time, and life goes back to normal. For some, the rupture might even become a positive experience, allowing a person to get away from a dysfunctional relationship and fall in love again.