Sahib S. Khalsa - US grants

DESCRIPTION (provided by applicant): Meditation, deep breathing and yoga comprise nearly a quarter of all CAM usage, although little is known about the neurobiological mechanisms by which meditative techniques exert their effects on health. Many of the disorders for which meditation is used, such as chronic pain, anxiety and drug addiction, are characterized by abnormal emotional experiences, abnormal perceptions of body states, and abnormal activity in brain networks that give rise to awareness of the internal state of the body. The practice of meditation explicitly highlights the importance of awareness directed towards the body, across tradition and experience level. The effectiveness of meditative techniques as a treatment for these disorders may lie in their ability to change awareness of the internal state of the body, by modifying the function of this brain network. The purpose of this project is to examine how meditation changes interoception: awareness of the internal state of the body. Rather than examining neural activity during the meditative state, I propose to examine neural activity during performance of an interoceptive task: heart beat detection. This task draws on components of the meditative process but is better characterized, providing quantifiable information about the nature of the subject's experience. Two studies will be conducted. The first will compare brain activity during heartbeat detection between experienced and beginning meditators. The second will longitudinally track changes in brain activity during heartbeat detection that result from learning the practice of meditation.

PROJECT SUMMARY Anorexia nervosa (AN) is a serious mental illness with one of the highest mortality rates of all psychiatric disorders. It is characterized by reduced caloric intake, pre-meal anxiety and avoidance of food; behaviors that often persist after weight restoration. How the experience of eating provokes such anxiety in anorexia nervosa is unknown. Altered anxiety expression has been suggested as one explanation, on the basis that anxiety disorders are well known antecedents to AN, are frequently comorbid, and due to the increased aggregation of anxiety disorders among first degree family members of affected individuals. We propose that the altered processing of interoceptive signals is an important mechanism contributing to the expression of meal associated anxiety and dysfunctional eating behaviors in AN, and that determination of the processes contributing to this dysregulation will yield novel insights into the illness pathophysiology. To evaluate the neurobiological underpinnings of meal associated anxiety and interoception, the current proposal will investigate how individuals with AN experience cardiorespiratory sensations during meal anticipation relative to two control groups: age and weight-matched healthy comparison women, and an anxious comparison group of women with generalized anxiety disorder (GAD). Cardiorespiratory interoception and meal anxiety will be assessed using a validated protocol of intravenous infusions of isoproterenol and saline, during the pre-meal anticipatory time period. Isoproterenol, a rapid peripherally acting sympathomimetic agent, is a reliable method to measure changes in cardiorespiratory sensation and the double-blinded bolus infusion approach was developed by the PI. To understand the neural processes underlying this interoceptive phenotype the PI has successfully adapted the isoproterenol infusion paradigm to the functional MRI environment, and proposes using Arterial Spin Labeling (ASL) to identify cerebral blood flow changes associated with interoceptive stimulation. This pharmacological-fMRI (phMRI) approach is optimal for identifying changes in brain activity induced by peripherally induced sensation. Aims 1 and 2 of the research will identify which interoceptive biomarkers are similar and different between patients with AN and GAD. Once identified, these neural interoceptive biomarkers will be used to predict illness outcomes at one year, for each patient group (Aim 3). At the conclusion of these studies, we will know whether interoceptive-based biomarkers can be used as predictors of poor mental health outcomes in individuals with AN or GAD. Collectively, these findings will lay the groundwork for determining whether this approach can be translated into a novel treatment intervention for anxiety in AN, for example, by augmenting cognitive behavioral therapy with pre-meal interoceptive exposure training, to enhance inhibitory fear learning and reduce the fear of food in AN.

PROJECT SUMMARY Dr. Sahib Khalsa is applying for the Mentored Patient-Oriented Career Development Award (K23) to support his growth as an independent researcher to delineate the pathophysiology of interoception (the brain body connection) in eating disorders. Anorexia nervosa (AN) is two to three-times deadlier than schizophrenia, bipolar disorder, and unipolar depression, yet the underlying pathophysiology and associated neural dysfunctions are poorly understood. Anticipating eating a meal makes individuals with AN fearful, which induces a state of Biased Interoceptive Anticipatory Signaling (BIAS) marked by a discrepancy between the actual interoceptive state and the subjective interoceptive experience. BIAS interferes with AN patients' ability to accurately sense what is happening in their bodies, which in turn reinforces fears of eating, food avoidance behaviors, and weight loss. To determine the neural basis of BIAS in AN, the candidate has developed a protocol that employs (a) interoceptive modulation using isoproterenol, a rapid peripherally acting sympathomimetic drug akin to adrenaline, (b) direct experimental manipulation of meal anticipation, which heightens anxiety in AN, and (c) functional magnetic resonance imaging to examine the brain's response to these manipulations. Weight-restored individuals with AN (to avoid the potentially confounding effects of starvation on measures of brain function) and sex and BMI matched healthy comparisons will undergo multi- level assessments focused on the negative valence domain and interoception. This proposal investigates the basic question ?how does the state of anticipating a meal induce fear and dysregulate the processing of body- relevant information in AN?? Addressing it will help to clarify the behavioral and brain processes that reinforce starvation in the presence of food availability, and will enable the development of specific food-focused fear extinction procedures. Dr. Khalsa's long-term career goal is to understand the neural sources of interoceptive dysregulation in eating disorders, and to develop novel treatments. The proposed research will accomplish first steps towards this goal by evaluating the role of interoception across levels of behavior, physiology and neural circuits in AN. The training activities of this project will allow Dr. Khalsa to develop expertise in pharmacological fMRI methodology, increased knowledge of advanced statistics, and enhanced expertise in eating disorder treatment. Dr. Khalsa has assembled a team of mentors uniquely suited to provide the required diversity of expertise. Dr. Paulus (LIBR Scientific Director and primary mentor) will provide expertise in psychiatric and pharmacological neuroimaging using interoceptive probes. Dr. Walter Kaye will provide mentorship in AN neurobiology and treatment. Dr. Jerzy Bodurka, LIBR Neuroimaging Core Director, will provide mentorship in fMRI data processing and structural/functional connectivity analyses. Dr. Danny JJ Wang will provide mentorship in perfusion MRI and the combination of pharmaco-imaging with ASL. The training and associated research will take place at LIBR, a psychiatric research institute with state-of-the-art neuroimaging facilities.

PROJECT SUMMARY Given that anorexia nervosa (AN) has the highest mortality rate of any psychiatric illness and current treatments show limited efficacy, there is a crucial need to better understand the brain mechanisms driving the pathophysiology of this disorder. This proposal combines an experimental medicine approach focused on gastrointestinal (GI) interoception with computational modeling to probe neural circuits of interoception and appetite-related gastric processing in AN. The goal is to identify perceptual and neural markers for AN at the individual patient level and apply machine learning methods to test clinical outcomes prediction longitudinally. Supported by our preliminary data, this proposal is based on the premise that the pathophysiology of AN includes a computational dysfunction manifested by cognitive suppression of the expected precision of afferent interoceptive signals associated with hunger, which reduces their motivational influence and facilitates maladaptive and avoidant eating behaviors. We propose a case-control study with 65 AN and 65 healthy comparisons who will undergo extensive baseline testing using a novel GI interoception probe during measurement of symptoms, behavior, circuits, and physiology. Sensory stimulation will occur during the premeal period, anchoring responses to an anticipatory context with high relevance to the disorder. These individuals will be followed for 180 days to examine clinical outcomes. A computational approach will examine the basic hypothesis that AN individuals have lower sensory precision for GI interoception and that the degree of sensory imprecision is related to clinical characteristics. Moreover, we will examine the relationship of this imprecision to circuit and physiological measures. We will then apply machine learning approaches to these neurophysiological and perceptual measures to longitudinally test the prediction of clinical outcomes. Achieving the aims of this project will provide unique insights into the pathophysiology of AN by arbitrating whether AN is a consequence of ?top-down? or ?bottom-up? dysregulation in the nervous system, which could transform our understanding of how intrinsic interoceptive disturbances lead to AN. Pragmatically, it will result in new technologies for identifying interoceptive dysfunction at the individual level, allowing psychiatry to develop diagnostic and predictive biomarkers of AN. Thus the neurocomputational assay of gastrointestinal interoception in AN could be used to develop low-cost, scalable, and objective tools for identifying dysfunction in individual patients, to facilitate neurobiologically-based definitions of recovery, and to predict the risk of relapse following treatment. Finally, this proposal lays the groundwork for the future development of precision psychiatric interventions such as perceptual retraining therapies to target (and recalibrate) abnormal brain- body interactions.