Predilection for Perplexion: Preoperative microstructural damage is linked to postoperative delirium.
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2025-01-09
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Postoperative delirium is the most common postsurgical complication in older adults and is associated with an increased risk of long-term cognitive decline and Alzheimer's disease (AD) and related dementias (ADRD). However, the neurological basis of this increased risk-whether postoperative delirium unmasks latent preoperative pathology or leads to AD-relevant pathology after perioperative brain injury-remains unclear. Recent advancements in neuroimaging techniques now enable the detection of subtle brain features or damage that may underlie clinical symptoms. Among these, Neurite Orientation Dispersion and Density Imaging (NODDI) can help identify microstructural brain damage, even in the absence of visible macro-anatomical abnormalities. To investigate potential brain microstructural abnormalities associated with postoperative delirium and cognitive function, we analyzed pre- and post-operative diffusion MRI data from 111 patients aged ≥60 years who underwent non-cardiac/non-intracranial surgery. Specifically, we investigated preoperative variation in diffusion metrics within the posterior cingulate cortex (PCC), a region in which prior work has identified glucose metabolism alterations in the delirious brain, and a key region in the early accumulation of amyloid beta (Aβ) in preclinical AD. We also examined the relationship of preoperative PCC NODDI abnormalities with preoperative cognitive function. Compared to patients who did not develop postoperative delirium (n=99), we found increased free water (FISO) and neurite density index (NDI) and decreased orientation dispersion index (ODI) in the dorsal PCC before surgery among those who later developed postoperative delirium (n=12). These FISO differences before surgery remained present at six weeks postoperatively, while these NDI and ODI differences did not. Preoperative dorsal PCC NDI and ODI values were also positively associated with preoperative attention/concentration performance, independent of age, education level, and global brain atrophy. Yet, these diffusion metrics were not correlated with cerebrospinal fluid Aβ positivity or levels. These results suggest that preoperative latent brain abnormalities within the dorsal PCC may underlie susceptibility to postoperative delirium, independent of AD-related (i.e., Aβ) neuropathology. Furthermore, these preoperative microstructural differences in the dorsal PCC were linked to preoperative deficits in attention/concentration, a core feature of postoperative delirium. Our findings highlight microstructural vulnerability within the PCC, a key region of the default mode network, as a neuroanatomic locus that can help explain the link between preoperative attention/concentration deficits and increased postoperative delirium risk among vulnerable older surgical patients.
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Reekes, Tyler H, Vinith R Upadhya, Jenna L Merenstein, Mary Cooter-Wright, David J Madden, Melody A Reese, Piper C Boykin, Noah J Timko, et al. (2025). Predilection for Perplexion: Preoperative microstructural damage is linked to postoperative delirium. medRxiv. 10.1101/2025.01.08.24319243 Retrieved from https://hdl.handle.net/10161/33998.
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Scholars@Duke
David Joseph Madden
My research focuses primarily on the cognitive neuroscience of aging: the investigation of age-related changes in perception, attention, and memory, using both behavioral measures and neuroimaging techniques, including positron emission tomography (PET), functional magnetic resonance imaging (fMRI), and diffusion tensor imaging (DTI).
The behavioral measures have focused on reaction time, with the goal of distinguishing age-related changes in specific cognitive abilities from more general effects arising from a slowing in elementary perceptual processes. The cognitive abilities of interest include selective attention as measured in visual search tasks, semantic and episodic memory retrieval, and executive control processes.
The behavioral measures are necessary to define the cognitive abilities of interest, and the neuroimaging techniques help define the functional neuroanatomy of those abilities. The PET and fMRI measures provide information regarding neural activity during cognitive performance. DTI is a recently developed technique that images the structural integrity of white matter. The white matter tracts of the brain provide critical pathways linking the gray matter regions, and thus this work will complement the studies using PET and fMRI that focus on gray matter activation.
A current focus of the research program is the functional connectivity among regions, not only during cognitive task performance but also during rest. These latter measures, referred to as intrinsic functional connectivity, are beginning to show promise as an index of overall brain functional efficiency, which can be assessed without the implementation of a specific cognitive task. From DTI, information can be obtained regarding how anatomical connectivity constrains intrinsic functional connectivity. It will be important to determine the relative influence of white matter pathway integrity, intrinsic functional connectivity, and task-related functional connectivity, as mediators of age-related differences in behavioral measures of cognitive performance.
Ultimately, the research program can help link age-related changes in cognitive performance to changes in the structure and function of specific neural systems. The results also have implications for clinical translation, in terms of the identification of neural biomarkers for the diagnosis of neural pathology and targeting rehabilitation procedures.
Judd Wendell Moul
Dr Judd Moul joined the Duke faculty in mid 2004 after a career in the US Army Medical Corps mainly at Walter Reed Army Medical Center. He is a retired colonel and a noted researcher and clinician in the area of prostate cancer and is a urologic oncologist. He served as the division chief of Duke Division of Urology from 2004 to 2011 and was named the James H Semans MD Professor of surgery in 2009 becoming Duke's first named endowed chair for urology. He was awarded the Gold Cystoscope Award from the American Urologic Association as well as Castle Connelly Physician of the year for Clinical Medicine in 2009. He has performed more than 1300 radical prostatectomies since joining the Duke faculty and is committed to outcomes research on this series and in other areas of prostate cancer. He served as the Editor for Prostate Cancer and Prostatic Dissease, a Nature Medicine journal, for more than a decade and is a popular speaker and lecturer having been visiting professor and keynote speaker throughout the US and the World. He is very committed to training residents and mentoring students and trainees.
Harvey Jay Cohen
Dr. Cohen's research program includes clinical research relating to aspects of the pathways to functional decline and reilience with aging, geriatric assessment, and cancer and anemia in the elderly.
Pathways to functional decline are being explored through the NIA funded Claude Pepper Older Americans Independence Center, and includes studies of the contributions of age related physiologic change, in particular changes in inflammatory parameters, comorbid diseases and conditions, environment, genetics, and the interactionas among them. Data are derived from several current studies as well as previously collected data sets from the Established Populations for Epidemiologic Studies of the Elderly (EPESE), National Long Term Care Survey, and the Chinese Longevity Study (with Dr. Zeng Yi). Previous work has demonstrated the important contributions of age related inflammation and coagulation activation to functional status. He is Co-PI of the Pepper Center Physical Performance Across the LifeSpan (PALS) study, which is a longitudinal cohort study of community dwelling adults from age 30-90+and includes functional measures and biomarkers on inflammation and metabolism.
Geriatric assessment approaches have been studied in a number of randomized and controlled studies and work is now concentrating on the application of Comprehensive Geriatric Assessment tools to the evaluation and treatment of elderly patients with cancer. This is an extension and continuation of a long standing interest in geriatric oncology. Previous studies have elucidated age-related patterns of disease presentation, treatment approaches, clinical trials, survivorship, quality of life, impact of comrobidities and functional outcomes. Dr. Cohen was co-chair, and now member of the Cancer in the Older Adult Committee of the Alliance for Clinical Trials in Oncology (ALLIANCE). A number of active studies and ongoing data bases aree being utilized to address these questions.
Anemia in the older adult is being addressed through an NIA funded U01 consortium (Dr. Cohen Co-PI). the current main study is an observational study followed by a pragmatic treatment trial for anemia in older adults with CHF, in collaboration with the Cardiovascular Research Network (CVRN) of the Health services research network (HSRN)
Joseph P. Mathew
Current research interests include:
1. The relationship between white matter patency, functional connectivity (fMRI) and neurocognitive function following cardiac surgery.
2. The relationship between global and regional cortical beta-amyloid deposition and postoperative cognitive decline.
3. The effect of lidocaine infusion upon neurocognitive function following cardiac surgery.
4. The association between genotype and outcome after cardiac surgery.
5. Atrial fibrillation following cardiopulmonary bypass.
Michael Devinney
My work uses translational neuroscience approaches, such as cerebrospinal fluid molecular assays, sleep EEG, cognitive testing, and delirium assessment to identify mechanisms of delirium. Delirium is a syndrome of disrupted attention and consciousness that occurs in ~20% of the >19 million older surgery patients and ~50% of the >5 million intensive care unit (ICU) patients in the United States every year. Delirium is also associated with increased risk for Alzheimer’s disease and related dementias (ADRD), yet there are no FDA-approved drugs to prevent it, due to a major gap in our understanding of its underlying mechanisms. Our current work aims to discover potential mechanisms of delirium that could be targeted in future studies. We have recently found that increased blood-brain barrier dysfunction is associated with postoperative delirium, but it is unknown what inflammatory mediators actually cross the disrupted blood-brain barrier to drive delirium. Using mass spectrometry proteomics, we are examining the relationship of proteins and inflammatory markers found in the cerebrospinal fluid 24-hours following surgery with postoperative delirium. We are also interested in strategies that potentially protect the blood-brain barrier following surgery. Since sleep disruptions can cause blood-brain barrier dysfunction, we are conducting a study to determine the efficacy of suvorexant to improve postoperative sleep and reduce delirium severity in older surgical patients. Finally, we are working to extend these investigations to ICU patients, who are often more severely affected by delirium and more frequently develop long-term sequelae such as post-ICU long-term cognitive impairment (that is similar in magnitude to Alzheimer’s disease and related dementias).
Jeffrey Nicholas Browndyke
Dr. Browndyke is an Associate Professor of Behavioral Health & Neurosciences in the Department of Psychiatry & Behavioral Sciences. He has a secondary appointment as Assistant Professor of Cardiovascular & Thoracic Surgery.
Dr. Browndyke's research interests involve the use of advanced neurocognitive and neuroimaging techniques for perioperative contributions to delirium and later dementia risk, monitoring of late-life neuropathological disease progression, and intervention/treatment outcomes. His research also involves novel telehealth methods for remote neurocognitive evaluation and implementation of non-invasive neuromodulatory techniques to assist in postoperative recovery and dementia risk reduction.
Dr. Browndyke's clinical expertise is focused upon geriatric neuropsychology with an emphasis in the assessment, diagnosis, and treatment of dementia and related disorders in adults and US veteran patient populations.
Miles Berger
My research team focuses on 3 areas:
1) We are interested in the mechanisms of postoperative neurocognitive disorders such as delirium, and the relationship between these disorders and Alzheimer's Disease and Related Dementias (ADRD). Towards these ends, we use a combination of methods including pre and postoperative CSF and blood sampling, functional neuroimaging, EEG recordings, rigorous biochemical assays, and cognitive testing and delirium screening. In the long run, this work has the potential to help us improve long term neurocognitive outcomes for the more than 20 million Americans over age 60 who undergo anesthesia and surgery each year.
2) We are interested in the idea that altered anesthetic-induced brain EEG waveforms can serve as indicators of specific types of preclinical/prodromal neurodegenerative disease pathology, specific cognitive domain deficits, and postoperative delirium risk. We are studying this topic in the ALADDIN study, a 250 patient prospective cohort study in older surgical patients at Duke. Many people have viewed anesthesia and surgery as a "stress test" for the aging brain; we hope that this work will help us learn how to develop a real-time EEG readout of this "perioperative stress test" for the aging brain, just as ECG analysis can provide a real-time readout of cardiac treadmill stress tests.
3) We are interested in how the APOE4 allele damages brain circuitry throughout the adult lifespan, and how this contributes to increased risk of late onset Alzheimer's disease as well as worse outcomes following other acute brain disorders such as stroke and traumatic brain injury (TBI). In particular, we are investigating the hypothesis that the APOE4 allele leads to increased CNS complement activation throughout adult life, which then contributes to increased synaptic phagocytosis and long term neurocognitive decline. We are also studying whether acutely modulating APOE signaling in older surgical patients with the APOE mimetic peptide CN-105 is sufficient to block postoperative CSF neuroinflammation and complement activation.
Our work is transdisciplinary, and thus our team includes individuals with diverse scientific and clinical backgrounds, ranging from neuropsychology and neuroimaging to proteomics, flow cytometry and behavioral neuroscience in animal models. What unites us is the desire to better understand mechanisms of age-dependent brain dysfunction, both in the perioperative setting and in APOE4 carriers.
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