For most people, the intense ache that follows the death of a loved one eventually softens, and daily life resumes. But for some, the pain does not ease with time—a condition known as prolonged grief disorder (PGD).
In a review publishing February 18 in the Cell Press journal Trends in Neurosciences, researchers examine what is known about the neurobiology of PGD. The team highlights how disruptions in reward-related brain networks may help explain why grief persists in some individuals and illuminate how PGD differs from depression and anxiety.
"Prolonged grief disorder is the new kid on the block in terms of psychiatric diagnoses," says lead author Richard Bryant, a long-time trauma researcher of the University of New South Wales in Australia. Although grief has long been studied, PGD was only formally recognized in 2018.
The core experience of PGD resembles typical grief, including intense yearning, longing, and emotional pain. But for about one in every 20 bereaved people, the pain persists and lasts beyond six months after the loss. They may feel that life has lost its meaning, part of their identity has disappeared, or they cannot accept death, even though they know it has occurred.
"It's not that it's a different type of grief," says Bryant. "It's just more that the person is stuck in the grief."
To understand why some people remain stuck, Bryant and his colleagues turned to the neurobiology of prolonged grief—a field that is still in its infancy and often relies on research with small sample sizes and varying experimental designs, complicating comparisons across studies.
Much of the research in the field comes from neuroimaging studies, which ask bereaved participants to recall or view reminders of the deceased during brain scans. Across these studies, PGD has been repeatedly linked to changes in reward-related brain circuits. These regions include the nucleus accumbens and orbitofrontal cortex, which are involved in desire and motivation, as well as the amygdala and insula, which play roles in emotion processing.
"It sort of gelled with this notion that grief is characterized by a craving or a longing for the deceased," says Bryant.
Some of the neural patterns observed are not unique to prolonged grief. Similar changes appear in depression and post-traumatic stress disorder. Given that these conditions share the same traits such as rumination and emotional distress, "it would be very strange if we didn't get that overlap," says Bryant. However, this poses a challenge for researchers to tease apart which brain changes are specific to PGD and whether the observed brain differences cause prolonged grief or result from it.
Looking ahead, Bryant emphasizes the need to work with larger groups of bereaved individuals over time to reveal how grief-related brain activity changes as some people recover while others do not.
"I hope to raise awareness," says Bryant. "To actually deal with prolonged grief, we need to recognize it as a disorder. We do have treatments that can address it, but we can't do that if we can't identify these people."
