This study aims to understand how the gut and the brain communicate in people with Irritable Bowel Syndrome (IBS) who also experience anxiety and depression. We want to see if changes in gut bacteria are linked to changes in brain function, and to find potential markers that could help in diagnosis or future treatments.

We are looking for two groups of volunteers aged 18 to 60 years: 1) 100 patients diagnosed with IBS who also have symptoms of anxiety or depression, and 2) 100 healthy volunteers for comparison. All participants must be right-handed.

Participants in this observational study will not receive any new drug or treatment. Instead, they will be asked to:

Complete questionnaires about their bowel symptoms, anxiety, depression, sleep, and thinking skills.

Provide a stool sample (about 5 grams) and a blood sample (about 5 ml).

Undergo a brain scan using a 7 Tesla MRI machine, which will take about 45-50 minutes. They will need to lie still during the scan.

Some IBS patients may be invited for a follow-up visit after 3 months to repeat the questionnaires and sample collection.

There are minimal risks involved. The MRI scan is non-radioactive and considered very safe, but some people may feel uncomfortable or claustrophobic inside the machine. Giving blood may cause brief pain, bruising, or, very rarely, infection. Your privacy is protected. All personal information and data will be coded and kept confidential, and will only be used for this research.

The main benefit to participants is receiving a detailed health assessment, including advanced brain imaging and analysis of gut bacteria, at no cost. There is no direct therapeutic benefit from participating, but the knowledge gained may help improve the understanding and future care of IBS.

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.

Adults (18-60 years) with irritable bowel syndrome (IBS) meeting Rome IV criteria and healthy right-handed volunteers, all with at least 6 years of education.