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One-Year Brain Structural Changes Are Associated with Postoperative Delirium and Delayed Resolution of Interleukin-6
Jinglei Lv1,2,3, Jenniffer Taylor1, Samantha Curtis4
1Central Clinical School, Faculty of Medicine & Health, The University of Sydney, Camperdown, NSW, Australia.
Medrxiv : the Preprint Server for Health Sciences
|May 18, 2026
Summary
Postoperative delirium in older adults is linked to brain structure changes, specifically hippocampal volume loss, one year after surgery. Inflammation may also play a role in these cognitive and structural declines.
Area of Science:
- Neuroscience
- Gerontology
- Radiology
Background:
- Postoperative delirium is a frequent complication in elderly patients, linked to neuroinflammation and cognitive decline.
- Previous research indicates a correlation between the number of surgical procedures and hippocampal volume loss in older adults.
- The association between hippocampal volume loss within one year post-surgery and postoperative delirium remains under investigation.
Purpose of the Study:
- To investigate the relationship between longitudinal brain structural changes, specifically hippocampal volume loss, and postoperative delirium in older adults.
- To explore the association between neuroinflammation markers (IL-6) and structural brain changes after surgery.
- To determine if gray matter volume loss and cortical thinning correlate with delirium severity and inflammatory markers.
Main Methods:
- Longitudinal structural MRI and plasma IL-6 levels were collected from 62 participants (>65 years) before and one year after major non-intracranial surgery.
- Hippocampal and subcortical volumes were quantified using FreeSurfer; cortical thickness was measured using the Desikan-Killiany atlas.
- Structural changes were analyzed in relation to peak Delirium Rating Scale (DRS) scores and changes in IL-6 levels.
Main Results:
- One-year loss in right hippocampal volume correlated significantly with peak postoperative DRS scores and increased IL-6 levels.
- Gray matter reductions were also observed in the right putamen and superior parietal cortex.
- Right putamen volume loss was linked to IL-6 changes, while superior parietal cortex thinning correlated with delirium severity.
Conclusions:
- Postoperative delirium in older adults is associated with longitudinal gray matter loss after surgery.
- Delayed resolution of inflammation may contribute to postoperative brain structural alterations.
- These findings highlight the link between surgical stress, inflammation, and neurodegeneration in the elderly.
