Irritable bowel syndrome and psychiatric illness: Three clinical challenges

Box

Other than fiber supplements, most traditional IBS medications are sedating and are associated with anticholinergic side effects. In Ms. H’s case, extreme caution is necessary before prescribing an antidepressant or antipsychotic because of dicyclomine’s additive sedating effects.

Case 2 concluded: After a thorough initial patient interview, the psychiatrist elects to treat Ms. H’s major depression with an antidepressant but delays the use of an antipsychotic to avoid additive sedation.

After talking with Ms. H’s family physician, the psychiatrist stops her dicyclomine and starts sertraline, 100 mg/d. She tolerates the sertraline well and the dosage is titrated across 1 month to 200 mg/d.

Four weeks later, Ms. H’s Beck Depression Inventory score has improved from 26 at baseline to 5, but her paranoid thoughts and frequent diarrhea persist. The psychiatrist adds low-dose olanzapine (5 mg at bedtime) to minimize extrapyramidal side effects. One month later, her depression and paranoia have resolved.

Ms. H’s gastroenterologist instructs her to begin taking alosetron, 1 mg bid, for her continued frequent diarrhea. Adding this agent to her sertraline/olanzapine regimen can lead to additive constipation and abdominal pain, so the psychiatrist monitors her psychiatric medications. One month later, she reports that her affect is much improved and her diarrhea is “gone.”

CASE 3: DEPRESSION AND ABDOMINAL PAIN

Mr. J, age 52, has had depression for 1 year. His depressive symptoms have improved significantly on fluoxetine, 20 mg/d; he once again enjoys life and has a more positive outlook.

The patient was in reasonably good health until about 1 month ago, when he began to experience abdominal pain. He has lost 14 lbs over the past month. He is not taking other medications.

The challenge: Find the cause of Mr. J’s persistent abdominal pain without undermining depression therapy.

Discussion: Although Mr. J’s symptoms might be side effects of fluoxetine, his abdominal pain and weight loss >10 lbs within 1 month are cause for concern. The American College of Gastroenterology has identified six alarm symptoms that could point to a serious medical problem in patients with severe abdominal pain (Box).⁷

Patients who exhibit any of these symptoms should be referred for endoscopic and stool studies. Colon cancer screening should be considered for all patients age 50 and older.

Patients with IBS usually present first to their primary care physicians with abdominal pain and altered bowel habits. These symptoms can occur in many gastrointestinal and systemic illnesses (Table 2).⁸

Table 2

Diagnosing irritable bowel syndrome: What to rule out

Case 3 concluded: The psychiatrist and primary care physician consult a gastroenterologist, who performs a colonoscopy and identifies a resectable Duke’s Class B adenocarcinoma in the transverse colon. A partial colectomy is performed.

Three years later, Mr. J is cancer-free and his depression is stable. The psychiatrist advises him to keep taking fluoxetine, 20 mg/d, because the stress of his cancer therapy increases the risk of depression recurrence.

Related resources

• National Institute of Diabetes and Digestive and Kidney Diseases —Irritable Bowel Syndrome www.niddk.nih.gov/health/digest/pubs/irrbowel/irrbowel.htm

Drug brand names

• Alosetron • Lotronex
• Aripiprazole • Abilify
• Buspirone • BuSpar
• Desipramine • Norpramin
• Dicyclomine • Bentyl
• Fluoxetine • Prozac
• Olanzapine • Zyprexa
• Sertraline • Zoloft

Disclosure

The author reports no financial relationship with any company whose products are mentioned in this article or with manufacturers of competing products.