Alzheimer's-related cortical atrophy is associated with postoperative delirium severity in persons without dementia

Abstract

Patients with dementia due to Alzheimer’s disease (AD) have increased risk of developing delirium. This study investigated the relationship between a magnetic resonance imaging (MRI)-derived biomarker associated with preclinical AD and postoperative delirium. Participants were older adults (≥70 years) without dementia who underwent preoperative MRI and elective surgery. Delirium incidence and severity were evaluated daily during hospitalization. Cortical thickness was averaged across a published set of a priori brain regions to derive a measure known as the “AD signature.” Logistic and linear regression was used, respectively, to test whether the AD signature was associated with delirium incidence in the entire sample (N=145) or with the severity of delirium among those who developed delirium (N=32). Thinner cortex in the AD signature did not predict incidence of delirium (odds ratio=1.15, p=.38), but was associated with greater delirium severity among those who developed delirium (b=−1.2, p=.014). These results suggest that thinner cortices, perhaps reflecting underlying neurodegeneration due to preclinical AD, may serve as a vulnerability factor that increases severity once delirium occurs.

Exploring Postoperative Cognitive Dysfunction and Delirium in Noncardiac Surgery Using MRI: A Systematic Review

“…These studies included a total population of total 269 surgical patients, 36 patient controls and 55 healthy controls. Six of the papers reported different MRI endpoints of the same large population consisting of 146 patients who underwent mixed surgery (hip or knee replacement and colectomy) [ 10 , 32 – 34 , 36 , 38 ]. The remaining studies comprise 23 patients who underwent partial lung resection [ 39 ], 31 patients who underwent total knee arthroplasty [ 37 ], 30 patients who underwent breast cancer surgery [ 40 ], and finally 39 patients who underwent open abdominal surgery [ 35 ].…”

“…Seven recent studies have investigated neural correlates of POD in patients without dementia [ 10 , 32 – 34 , 36 , 38 , 39 ]. In a retrospective case-control study of brain metastasis-free patients undergoing pneumonectomy or lobectomy due to non-small-cell lung cancer, a set of delirium cases was identified retrospectively by a chart-based CAM review of medical records [ 39 ].…”

“…Post hoc analysis did not reveal a correlation between intracranial volume and risk ratio of POD (RR = 1.41 (0.60–3.32)). Further MRI analysis of imaging data from subsets of the same study population has been reported in five separate publications [ 32 – 34 , 36 , 38 ]. In the first publication, the authors failed to find any significant correlation between relative risk of delirium incidence and total volume of cerebral white matter hyperintensity (RR = 0.966 (0.919–1.016), p = 0.18), brain parenchymal volume (global brain atrophy) (RR = 0.997, p = 0.367), or hippocampal volume (RR = 1.37, p = 0.545), both with and without adjustment for age, gender, and cognitive performance ( p values stated here were for the adjusted models) [ 34 ].…”

“…Stated as secondary endpoints, the global CBF and regional CBF in parietal lobe were both correlated to cognitive performance tests including trails B ( p = 0.034) and digit symbol substitution ( p = 0.049). In the fifth and final publication, the investigators calculated the cortical thickness in mm of nine predefined brain regions related to Alzheimer's disease in 145 patients (of the 146 patients who underwent presurgical MRI scans) [ 38 ]. The cortical thickness was not associated with risk of delirium (OR = 1.15 (0.84–1.57), p = 0.38), but is was inversely associated with delirium severity in a regression model (coefficient −1.2 (−2.2 to −0.27), p = 0.014).…”

“…The studies included in current review did carefully exclude confounding factors (e.g., patients with dementia). In particular, the SAGES studies did also control for other important confounding factors (cognitive status, age, gender, and vascular comorbidities) [ 10 , 32 – 34 , 36 , 38 ]. Despite this effort, the SAGES studies suffer from lack of a priori endpoints.…”