Predilection for Perplexion: Preoperative microstructural damage is linked to postoperative delirium

Area of Science:

• Neuroscience
• Geriatric Medicine
• Radiology

Background:

• Postoperative delirium (POD) is common in older adults, increasing dementia risk.
• The neurological basis linking POD to long-term cognitive decline is unclear.
• Neurite Orientation Dispersion and Density Imaging (NODDI) detects subtle microstructural brain damage.

Purpose of the Study:

• Investigate preoperative brain microstructural abnormalities in older adults susceptible to POD.
• Examine the relationship between these abnormalities, POD, and preoperative cognitive function.
• Determine if POD susceptibility is linked to Alzheimer's disease (AD) pathology.

Main Methods:

• Diffusion MRI (including NODDI) analyzed pre- and post-operatively in 111 older surgical patients.
• Focused on the posterior cingulate cortex (PCC), a region implicated in AD and delirium.
• Correlated diffusion metrics with POD development and preoperative cognitive performance.

Main Results:

• Patients who developed POD showed preoperative increases in free water (FISO) and neurite density index (NDI), and decreased orientation dispersion index (ODI) in the dorsal PCC.
• FISO differences persisted postoperatively; NDI and ODI differences did not.
• Preoperative PCC NDI and ODI correlated with attention/concentration, independent of age, education, and atrophy, but not with CSF Aβ levels.

Conclusions:

• Preoperative microstructural abnormalities in the dorsal PCC may predispose individuals to POD, irrespective of AD pathology.
• These PCC abnormalities are linked to preoperative attention deficits, a core feature of POD.
• Microstructural vulnerability in the PCC may explain the link between attention deficits and POD risk in older adults.