Prolonged grief disorder in later life: advancing our understanding of biopsychosocial mechanisms to guide future personalized interventions.

Grief is a near-universal yet profoundly traumatic human experience, symbolizing a testament to the depth of our emotional bonds while reminding us of life's fragility. Although most individuals adapt to loss over time, 3-10% develop Prolonged Grief Disorder (PGD), a chronic and debilitating condition recognized in both the DSM-5-TR and ICD-11. Older adults are particularly vulnerable: PGD in later life poses significant public health risks, including adverse physical health outcomes, cognitive decline, and increased premature mortality, underscoring the urgent need for early identification and effective interventions in this population. This narrative review examines psychological, social, and neurobiological perspectives on grief, highlighting distinctions between acute, integrated, and PGD trajectories. We trace the evolution of PGD as a diagnostic entity and review its risk factors, clinical presentation, comorbidities, assessment, and current treatment approaches. We then propose a neurobiological model of late-life PGD, grounded in cognitive neuroscience and emphasizing the roles of key intrinsic brain networks: the Salience Network, Default Mode Network, and Executive Control Network. Finally, we outline future directions for the field, calling for neuroimaging studies that integrate biological markers with psychosocial factors to refine diagnosis and inform targeted interventions. This review advocates for a biopsychosocial framework to advance understanding and treatment of PGD in older adults.