elucidating mechanisms that underlie the symptomatology of functional dyspepsia using novel techniques and its therapeutic validation using neuromodulators

Conditions: Functional Disorder of Stomach; Healthy

Summary: the goal of this study is to investigate the mechanisms of impaired gastric accommodation and emptying, dysfunctional duodenum, and micro-inflammation using novel imaging techniques of spect/ct, gastric emptying scintigraphy, mri, high-resolution manometry, and inflammatory biomarkers, as well as to validate these mechanisms using a therapeutic trial of neuromodulator (mirtazapine) in functional dyspepsia (fd) and health. the main objective\[s\] it aims to answer are: * to investigate impaired gastric accommodation through spect/ct imaging and high-resolution manometry findings of the stomach fundus. * to investigate impaired gastric emptying through gastric emptying scintigraphy * to investigate for a dysfunctional duodenum through mri imaging of the duodenum. * to investigate micro-inflammation through spect/ct standard uptake value (suv), inflammatory biomarkers (eosinophils, mast cells, il-6, il-10) and mucosal barrier marker (e-cadherin). * to investigate if a therapeutic trial of a neuromodulator agent, mirtazapine, ameliorates symptoms of fd through improvement in impaired gastric accommodation. for objectives 1-4, fd patients and healthy volunteers will be consecutively recruited, and all will undergo spect/ct, mri, high-resolution manometry and biomarkers, and data acquired from these tests will be analyzed. for objective 5, the enrolled participants who did all baseline tests/markers are given mirtazapine for four weeks, and all tests/markers, except biomarkers and mri, are repeated at the end of the trial


Eligibility criteria:
inclusion criteria (healthy): * age 18 and above, up to 65 years old * no current gi symptoms (as assessed by history taking during screening and based on the investigators' collective judgement) * no previous gi illness (as determined by clinically significant findings from medical history taking and vital signs) * no chronic medical illness e.g., chronic neurological, cardiovascular, pulmonary, endoscirne and hematological disorders, as well as psychiatric disorders exclusion criteria (healthy): * bmi of less than 18.50 and more than 29.99 * had undergone any abdominal surgery except appendicectomy, tubal ligation, or caesarean section * females that are pregnant, expecting to become pregnant during the study period, or breastfeeding * aversion to test meals * use of medications that may alter gastrointestinal function and motility * contraindication for mri examination e.g., cardiac pacemaker, ferromagnetic implants, claustrophobia inclusion criteria (fd patients): * age 18 and above, up to 65 years old * satisfy the diagnosis of fd as per rome iv criteria * absence of organic disorders that explain dyspepsia in patients such as autoimmune disease, inflammatory disease or brain trauma * no other chronic medical illnesses (including chronic neurological, cardiovascular, pulmonary, endocrine and hematological disorders) and psychiatric disorders exclusion criteria (fd patients): * positive helicobacter pylori test * presence of esophagitis, gastric atrophy, heartburn as predominant symptom, history of peptic ulcer or major abdominal surgery * medications that potentially affects gastrointestinal motility or sensitivity (eg: acid suppressant, prokinetics, corticosteroids, nsaids and analgesics apart from paracetamol) * aversion to test meals * recent trauma to the abdomen * patients on antipsychotic or antidepressant in the last 6 weeks * contraindication for mri examination e.g., cardiac pacemaker, ferromagnetic implants, claustrophobia

Keywords: functional dyspepsia gastric accommodation gastric emptying micro inflammation