istockphoto/christine balderas

Editor's Note: This story will be published in the October/November issue of Scientific American Mind.

Losing a loved one is always painful, but for most people time eventually heals the wounds. For about 10 to 20 percent of the bereaved, however, accepting and getting over a loss remains extremely difficult, even years later. Now researchers have come a step closer to elucidating the neurobiological underpinnings of this condition called complicated grief (CG). A new functional magnetic resonance imaging (fMRI) study, published online in May in the journal NeuroImage, shows that in CG patients reminders of the deceased activate a brain area associated with reward processing, pleasure and addiction.

A team led by Mary-Frances O’Connor of the University of California, Los Angeles, studied 23 women—11 of whom suffered from CG—who had lost a mother or sister to breast cancer in the past five years. While in the scanner, the women saw pictures and words that reminded them of their loved one. Brain networks associated with social pain became activated in all women, but in the CG patients reminders of the deceased also excited the nucleus accumbens, a forebrain area most commonly associated with reward.

O’Connor believes this continued neural reward activity probably interferes with adaptation to the new situation. “When we see a loved one or reminders of a loved one, we are cued to enjoy that experience,” she says. “But when a loved one dies, our brains have to adapt to the idea that these cues no longer predict this rewarding experience.” Scientists do not yet know why some people adapt better than others do.

O’Connor hopes the findings will lead to new treatment strategies that will “help the brains and minds of CG patients understand that the person is gone.”