Irritable Bowel Syndrome (IBS) Functional Magnetic Resonance Imaging (fMRI) With Desipramine

Inclusion Criteria:

- IBS subjects with- and without comorbid somatization features will be recruited from
the sources highlighted above.

- To be eligible, subjects will have to be between 18 and 90 years of age (inclusive)
and qualify for a diagnosis of irritable bowel syndrome according to the criteria set
forth in the Rome III criteria for the Diagnosis of Functional GI Disorders.

- IBS patients will then be assessed in terms of comorbid somatization as determined
using the Patient Health Questionnaire-15 (PHQ-15).

- For this particular study, only subjects with high somatization (PHQ ≥ 10 or low
somatization (PHQ ≤5) will be considered for enrollment.

- Verification of somatization status will be performed using a formal structured
interview process (Diagnostic Interview Schedule, DIS).

- Persons are eligible to participate without regard to race or ethnicity.

- Given sex differences in cerebral responses to noxious stimuli and the greater
prevalence of IBS in women, only female participants will be sought in this study.

- Also, in view brain hemispheric differences between left- and right-hand dominant
individuals and the greater prevalence of right-handedness, all participants must be
right-handed

Exclusion Criteria:

- Persons are excluded from participation for having various psychiatric, medical, and
other characteristics.

- Psychiatric/cognitive exclusions include any of the following: active suicidal or
homicidal ideation or a history of attempted suicide, current excessive alcohol use or
other substance abuse disorders, active major depression, anxiety disorder, bipolar
depression or any psychotic disorder, unwillingness to be randomized or provide
informed consent, inability to communicate with staff or significant cognitive
impairment.

- Medical and other exclusions include any of the following: renal or hepatic disease or
impairment, diabetes, cardiovascular disease, cardiac arrythmia, cerebrovascular
disease, or breastfeeding, pregnant, or imminent intention of pregnancy, history of
seizures or primary neurological disorder, head trauma, brain damage, hyper- or
hypothyroidism, history or abdominal surgery (other than
cholecystectomy/appendectomy), or known structural GI disorder (Crohn's disease,
etc.), contraindication to MRI (metallic implant, pacemaker), or rectal balloon
distention (e.g., proctitis/colitis).

- Exclusions related to medications:

1. Analgesics (narcotics, NSAIDs; acetaminophen OK)

2. Muscle relaxants

3. Psychoactive agents (antidepressants, antipsychotics)

4. Other medications (phenytoin; amphetamines, prescription weight-loss drugs, or
benzodiazepines)

5. Thyroid medication

6. Anticholinergic medications or other IBS medications (hyoscyamine, dicyclomine)

7. Cytochrome p450 substrates

8. Participation in any clinical trial using any other drug.