Grief and bereavement: A pre-registered systematic review of neuroimaging studies.

Grief is a universally experienced response to the loss of a significant person, representing a profoundly stressful life event that can have lasting impacts on mental and physical health. Despite its inevitability, the neural mechanisms underlying grief remain poorly understood, hindering the development of effective interventions to improve outcomes for individuals coping with loss. To address this gap, we systematically reviewed functional and structural magnetic resonance imaging (MRI) studies related to brain connectivity, structural changes, peripheral physiology, and neuroendocrine, immune, and psychological correlates of grief. Functional MRI (fMRI) studies have consistently found associations between grief and neural activity, connectivity, and structure in networks related to emotion regulation, reward processing, and cognitive control, with some studies documenting heightened reactivity in regions such as the posterior and subgenual anterior cingulate cortex, medial/superior frontal gyrus, cerebellum, and amygdala. In turn, structural MRI studies have found reductions or differences in hippocampal, amygdala and supramarginal gyrus volumes, white matter abnormalities, and potential cognitive decline in those with prolonged grief. These neurobiological measures have been associated with clinical outcomes, including prolonged grief disorder, posttraumatic stress disorder, depressive disorders, and increased risk of cardiovascular disease. Studies focusing on individuals with PTSD or prolonged grief, especially following the loss of a child or spouse, have revealed hippocampal atrophy and an increased risk for brain pathologies, including neurodegenerative diseases. Future research should use longitudinal, multi-modal, and prospective study designs to identify neurobiological markers of prolonged grief. Integrating these findings with interventional research may help inform individualized strategies to promote neuroimmune resilience and improve grief management.