Trial By Error: Another Letter About Mahana; BerkeleyWellness on IBS Study

By David Tuller, DrPH

I have been trying to find out why Mahana Therapeutics, a San Francisco-based start-up, has chosen to disseminate misleading information about a web-based cognitive behavior therapy program for people with irritable bowel syndrome. Because Mahana’s co-founder and CEO, Rob Paull, has not responded to my letters, I have contacted some of those listed as science advisors on the company’s website.

Earlier this month, I sent one such letter to Dr Mel Heyman, a pediatric gastroenterologist at University of California, San Francisco–one of Berkeley’s sister UC campuses. I received an automatic e-mail response that Dr Heyman was out of the office for a period of time. Last week, after his stated return date, I sent another letter:

Dear Dr Heyman–

I know you have been away and undoubtedly have many matters to attend to. I wanted to re-send the message I sent a couple of weeks ago about Mahana Therapeutics, given your role as one of the company’s gastroenterology advisor.

As I have noted in multiple posts on the science site Virology Blog, the changes in symptom severity reported for Mahana’s web-based cognitive behavior therapy program for irritable bowel syndrome cannot reasonably be described as “substantial,” “durable,” “dramatic,” and “potentially game-changing.” Yet that is how Mahana has described them in a press release and on its website.

I have so far received no response from my multiple attempts to reach the company itself, which is why I am reaching out to you and others serving as scientific advisors. I look forward to hearing from you. (I have once again cc’d Vincent Racaniello, a Columbia professor of microbiology and host of Virology Blog.)

Thanks much!


David Tuller, DrPH
Senior Fellow in Public Health and Journalism
Center for Global Public Health
School of Public Health
University of California, Berkeley

********** is a popular consumer health website whose content is vetted and approved by experts from the university. Last year, the site posted my interview with Dr Steve Olson, the Kaiser Permanente doctor who spearheaded the medical organization’s efforts to switch gears on its approach to the illness (or cluster of illnesses) variously referred to as myalgic encephalomyelitis, chronic fatigue syndrome, ME/CFS, and CFS/ME, among other terms. It also featured my interview with journalist Maya Dusenberry, the author of Doing Harm: The Truth About How Bad Medicine and Lazy Science Leave Women Dismissed, Misdiagnosed, and Sick.

Last week, published a short article about the UK study at the root of the inflated claims that CBT is an effective treatment for IBS symptoms. The piece was blunt about the limitations of the findings. Here is the text:

Irritable bowel syndrome (IBS) is a common gastrointestinal condition characterized by cramping, bloating, gas, and diarrhea or constipation. It likely has multiple causes, and many patients continue to suffer despite taking medication. Cognitive behavioral therapy (CBT) has sometimes been recommended as a treatment based on the notion that it can help patients reduce stress, change their eating patterns, and modify how they think about the illness. But now the largest study to date of CBT for IBS has shown that it has little impact in reducing symptom severity.

The UK study, conducted by investigators at King’s College London and the University of Southampton, included 558 people with unresolved IBS. Participants were randomly assigned to receive telephone-delivered CBT, web-based CBT, or no intervention. All three groups continued to receive their usual medical treatment. The study did not test in-person CBT. The 12-month and 24-month results were published in 2019 in, respectively, the journals Gut and Lancet Gastroenterology & Hepatology.

At 12 months, those in both CBT groups reported a statistically significant reduction on the standard scale for assessing IBS symptoms. However, the average benefit for telephone-delivered CBT over treatment-as-usual was only slightly above the threshold considered clinically significant. At 24 months, the average benefit in this group was no longer clinically significant.

For the web-based group, the average benefit at 12 months was already below the critical threshold for clinical significance. At 24 months, the average benefit was neither clinically significant nor statistically significant.

Both groups reported modest benefits in other domains, such as social adjustment and depression, not surprising after a course of CBT. Given the weak results for reductions in symptom severity, however, these reported improvements likely have little or nothing to do with treating the illness itself.

Moreover, this was an unblinded trial relying solely on self-reported rather than objective outcomes. Since this kind of study design is likely to generate an unknown amount of bias, any positive findings should be taken with caution.

3 thoughts on “Trial By Error: Another Letter About Mahana; BerkeleyWellness on IBS Study”

  1. Great letter David. You state your points so politely.
    Thank you for following up this important issue.

  2. Well done to for providing such a clear and accurate summary of this IBS/CBT study. Wouldn’t it be lovely if all medical journal abstracts were as informative?

  3. Pingback: Trial By Error: Another Letter About Mahana; BerkeleyWellness on IBS Study – Virology Hub

Comments are closed.

Scroll to Top