Miles Berger - US grants

[unreadable] DESCRIPTION (provided by applicant): Major depression is a common mental illness thought to arise in part from decreased serotonin (5-HT) neurotransmission. Recent evidence suggests that this decrease may arise from increased expression of inhibitory 5-HT1A autoreceptors (5-HT1A-AR) on 5-HT neurons. To model this aspect of the pathophysiology of depression, I have created transgenic mice designed to overexpress 5-HT1A-AR; I hypothesize that these mice will have decreased 5-HT transmission and depressive-like behavior. Aim 1: Validate 5-HT1A-AR overexpression in transgenic mice by quantitative autoradiography and immunocytochemistry. Aim 2: Determine the effect of 5-HT1A-AR overexpression on 5-HT neurotransmission by in vivo microdialysis and electrophysiology. Aim 3: Determine the effect of 5-HT1A-AR overexpression in tests of neurovegetative function and depressive-like behavior. These studies should increase our understanding of the underlying causes of depression and other affective disorders, and may lead to new treatment strategies for patients suffering from these disorders. [unreadable] [unreadable]

? DESCRIPTION (provided by applicant): Tau is a microtubule-associated protein found in neuronal axons, and is released after neuronal injury. Increased cerebrospinal fluid (CSF) tau levels predict the development of Alzheimer's disease, and increased CSF tau levels also predict worsened outcomes after subarachnoid hemorrhage and traumatic brain injury. We have found increased CSF tau levels in patients after surgery and anesthesia, and numerous investigators have found that anesthesia and surgery increase tau levels and cause memory deficits in animal models (6-8). Taken together, these findings suggest the possibility that changes in CSF tau levels may also be associated with neurocognitive changes after anesthesia and surgery in our patients. Indeed, multiple studies have found neurocognitive changes (i.e. post-operative delirium and cognitive dysfunction) occur in a substantial fraction of patients after surgery and anesthesia, and a major risk factor for these disorders is age >60. Post-operative delirium and cognitive dysfunction are major complications in elderly patients: they are associated with decreased ability to perform IADLs, decreased quality of life, early exit from the work force, and increased one year mortality. Yet, the underlying pathophysiology of post-operative delirium and/or cognitive dysfunction is unclear, which impedes our ability to treat these syndromes and improve patient outcomes. In this application, we will extend our preliminary work demonstrating significant increases in CSF tau levels after anesthesia and surgery by determining the long-term trajectory of these perioperative CSF tau increases, and whether they are associated with delirium, cognitive dysfunction, or altered functional neural connectivity in elderly surgical patients vs age-matched controls. We will also obtain data on the relationship between changes in CSF tau levels, IADLs and quality of life in these patients' vs controls. This study is the first, adequately powered prospective clinical study to determine the long-term trajectory of perioperative changes in CSF tau levels, and to correlate these changes with changes in cognitive function, brain connectivity and functional status. Understanding these relationships could help develop strategies to prevent adverse effects of anesthesia and surgery in the elderly and to improve neurocognitive function for the millions of patients over age 60 who undergo perioperative care each year in the United States.

This is a K76 Beeson career development award for Dr. Miles Berger, a geriatric neuro- anesthesiologist with a focus on postoperative cognitive disorders. Each year >16 million older Americans undergo anesthesia and surgery, and up to 40% of these patients develop postoperative cognitive dysfunction (POCD), a syndrome of postoperative thinking and memory deficits. Although distinct from delirium, POCD (like delirium) is associated with decreased quality of life, long term cognitive decline, early retirement, increased mortality, and a possible increased risk for developing dementia such as Alzheimer?s disease. We need strategies to prevent POCD, but first, we need to understand what causes it. A dominant theory holds that brain inflammation causes POCD, but little work has directly tested this theory in humans. Our preliminary data strongly suggest that there is significant postoperative neuro-inflammation in older adults who develop POCD. In this K76 award, we will prospectively obtain pre- and post-operative cognitive testing, fMRI imaging and CSF samples in 200 surgical patients over age 65. This will allow us to evaluate the role of specific neuro-inflammatory processes in POCD, its underlying brain connectivity changes, and postoperative changes in cerebrospinal fluid (CSF) Alzheimer?s disease (AD) biomarkers, such as the microtubule-associated protein tau. This project will advance understanding of neuro-inflammatory processes in POCD and clarify the potential link(s) between these processes and postoperative changes in AD pathology, in line with the National Institute of Aging?s mission to understand aging and fight cognitive decline due to AD. During this K76 grant period, Dr. Berger will also complete an individually tailored MS degree in Translational Research that will include training in immunology methods, fMRI imaging, cognitive neuroscience, geroscience, and physician leadership. This career development plan will give Dr. Berger the transdisciplinary skills to pursue his longer term goal of improving postoperative cognitive function for the more than 16 million older Americans who have anesthesia and surgery each year.