Identifying Multidimensional Signatures of Gastric Interoception in Functional Dyspepsia

Participant Inclusion Criteria-- Functional Dyspepsia Group: * Males and females; ages 18-65 years * Rome V functional dyspepsia post-prandial distress syndrome subtype * Negative upper endoscopy or upper GI series to rule out structural/organic cause for FD * greater than or equal to 5.5 gut interoceptive awareness score (by VSI awareness subscale) * Fluent in English * Willing and able to provide informed consent * Stable dose for 30 days prior to Visit 1 if on a neuropsychiatric medication (e.g., TCA, SNRI, SSRI mirtazapine, atypical antipsychotic, gabapentin, buspirone, pregabalin) * No current plans to initiate a new or change dosing on a neuropsychiatric medication within the study period Anorexia Nervosa Group: * Males and females; ages 18-65 years * DSM-5 anorexia restricting-type by the Eating Disorder Module in the Diagnostic Interview for Mood, Anxiety, and OCD and related Neuropsychiatric Disorders (DIAMOND) * greater than or equal to 5.5 gut interoceptive awareness score (by VSI awareness subscale) * Fluent in English * Willing and able to provide informed consent * Stable dose for 30 days prior to Visit 1 if on an SSRI * No current plans to initiate a new neuromodulator * No current plans to initiate a new SSRI or change dosing on an SSRI Healthy Controls: * Males and females; ages 18-65 years * BMI greater than or equal to 18.5 kg/m2 * Fluent in English * Willing and able to provide informed consent Participant Exclusion Criteria-- Functional Dyspepsia Group: * Presence of other conditions that could explain the patient's symptoms by medical chart: * Pyloric or intestinal obstruction (by EGD, UGI, or Abdominal CT) * Active H.pylori (by CLO test or stool antigen test) * Active inflammatory bowel disease * Eosinophilic gastroenteritis or eosinophilic esophagitis * Acute renal failure * Chronic renal failure (serum creatinine \>3 mg/dL) and/or on hemodialysis or peritoneal dialysis * Acute liver failure * Any acute gastrointestinal process * Any plausible structural or metabolic causes * Heartburn as predominant symptom * History of peptic ulcer * Symptom resolution with antisecretory therapy (PPI use for other reasons that did not resolve FD symptoms will be allowed) * Endorses any contraindications to MRI * Body weight of 450 lbs or greater or BMI of 50 kg/m2 or greater (limit of MRI table) * Allergy to pineapple (used in the test meal during MRI) * History of GI tract surgery or any serious medical condition (e.g., cancer) * Pregnancy/breastfeeding within the last 8 weeks * Uncontrolled diabetes (indicated by HbA1c greater than or equal to 7%) by chart * Narcotic analgesics greater than three days per week * Cannabinoid use greater than three days per week * Intellectual disability by history * Illiteracy * History of weight/shape-based eating disorder including anorexia nervosa by DIAMOND * Current binge eating by DIAMOND * Current self-induced vomiting by DIAMOND * Current laxative or diuretic misuse by DIAMOND * Current substance/alcohol use disorder within past year by DIAMOND * Current/history of psychosis by DIAMOND * Current mania by DIAMOND * Active suicidal ideation by modified DIAMOND abbreviated suicide module; passive suicidal ideation is allowed * Inability or unwillingness to consume food by mouth * Inability to provide informed consent Anorexia Nervosa Group: * Diagnosis of chronic gastrointestinal disorder * Rome V functional dyspepsia * Endorses any contraindications to MRI * Body weight of 450 lbs or greater or BMI of 50 kg/m2 or greater (limit of MRI table) * Allergy to pineapple (used in the test meal during MRI) * History of GI tract surgery or any serious medical condition (e.g., cancer) * Pregnancy/breastfeeding within the last 8 weeks * Uncontrolled diabetes (indicated by HbA1c greater than or equal to 7%) by chart * Narcotic analgesics greater than three days per week * Cannabinoid use greater than three days per week * Intellectual disability by history * Illiteracy * Current binge eating by DIAMOND * Current self-induced vomiting by DIAMOND * Current laxative or diuretic misuse by DIAMOND * Current substance/alcohol use disorder within past year by DIAMOND * Current/history of psychosis by DIAMOND * Current mania by DIAMOND * Active suicidal ideation by DIAMOND abbreviated suicide module; passive suicidal ideation is allowed * Inability or unwillingness to consume food by mouth * Inability to provide informed consent * Current use of neuropsychiatric medication other than an SSRI (e.g., TCA, SNRI, mirtazapine, atypical antipsychotic, gabapentin, buspirone, pregabalin) Healthy Controls: * Diagnosis of chronic gastrointestinal or pain disorder * Rome V functional dyspepsia * greater than or equal to 5.5 gut interoceptive awareness score (by VSI awareness subscale) * Current use of a medication known to influence gastric sensorimotor functions (including neuromodulators and SSRIs) * Active psychiatric disorder including a feeding/eating disorder by DIAMOND * Endorses any contraindications to MRI * Body weight of 450 lbs or greater or BMI of 50 kg/m2 or greater (limit of MRI table) * Allergy to pineapple (used in the test meal during MRI) * History of GI tract surgery or any serious medical condition (e.g., cancer) * Pregnancy/breastfeeding within the last 8 weeks * Uncontrolled diabetes (indicated by HbA1c greater than or equal to 7%) by chart * Narcotic analgesics greater than three days per week * Cannabinoid use greater than three days per week * Intellectual disability by history * Illiteracy * Current binge eating by DIAMOND * Current self-induced vomiting by DIAMOND * Current laxative or diuretic misuse by DIAMOND * Current substance/alcohol use disorder within past year by DIAMOND * Current/history of psychosis by DIAMOND * Current mania by DIAMOND * Active suicidal ideation by DIAMOND modified suicide module; passive suicidal ideation is allowed * Inability or unwillingness to consume food by mouth * Inability to provide informed consent