Anxiety and Depression in IBS: A Brain-Gut Axis Study

Inclusion Criteria: 1. Right-handed, aged 18-60 years, with more than 6 years of education; 2. Meeting the Rome IV diagnostic criteria for IBS: Symptoms have been present for at least 6 months, and for the last 3 months, the following criteria are met: recurrent abdominal pain or discomfort, with symptoms occurring on at least 3 days per month in the last 3 months, associated with two or more of the following: 1) Improvement with defecation; 2) Onset associated with a change in frequency of stool; 3) Onset associated with a change in form (appearance) of stool; 3. The following symptoms support the diagnosis of IBS: 1) Abnormal stool frequency: \<3 bowel movements per week or \>3 bowel movements per day; 2) Abnormal stool form: lumpy/hard stool or mushy/watery stool; 3) Straining during defecation; 4) Urgency or a feeling of incomplete evacuation; 5) Passage of mucus; 6) Bloating. Exclusion Criteria: 1. History of anti-anxiety/depressant medication use (e.g., SSRI/SNRI, Chinese patent medicines) within the past 1 month; 2. History of antibiotic or probiotic use within the past 1 month; 3. Other gastrointestinal diseases such as IBD, intestinal obstruction, or history of gastrointestinal surgery; 4. Current or past history of psychiatric or neurological disorders, such as psychosis, brain tumors, or impaired consciousness; 5. Concurrent severe hepatic or renal insufficiency, cardiovascular or cerebrovascular diseases, or malignant tumors; 7.0T MRI Contraindications: Presence of ferromagnetic implants (e.g., cardiac pacemakers, defibrillators, neurostimulators, aneurysm clips, cochlear implants, or any metallic foreign bodies); Non-ferromagnetic implants (e.g., titanium alloy, orthopedic implants), various types of intrauterine devices, various types of non-removable dentures (including dental implants); Presence of metallic foreign bodies (e.g., metal fragments, shrapnel, or filings in the eyes or body), such as in individuals engaged in welding work or with a history of metal item trauma; Tattoos or permanent makeup (e.g., eyebrows, lips) applied within the past month; Claustrophobia; Fever. HC Group Inclusion Criteria (all must be met): 1. Right-handed, aged 18-60 years, with more than 6 years of education; 2. All physiological indicators are within normal ranges, with no signs of disease; 3. No family history of psychiatric or neurological disorders.