Drug/psychotherapy RCT: A research methods refresher for psychotherapy chapter

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The Intro Psych therapy chapter is a good place to reinforce what students have learned about research methods throughout the course.

In this freely available 2022 study, researchers wondered about the effectiveness of a particular medication (naltrexone combined with bupropion) and a particular type of psychotherapy (behavioral weight loss therapy) as a treatment for binge-eating disorder (Grilo et al., 2022). First, give students a bit of background about binge-eating disorder. If you don’t have the DSM-V (with or without the TR) handy, this Mayo Clinic webpage may give you what you need (Mayo Clinic Staff, 2018). Next, let students know that naltrexone-bupropion work together on the hypothalamus to both reduce how much we eat and increase the amount of energy we expend (Sherman et al., 2016). It’s a drug combination approved by the FDA for weight loss. Lastly, behavioral weight loss therapy is all about gradual changes to lifestyle. That includes gradual decreases in daily calories consumed, gradual increases in nutritional quality, and gradual increases in exercise.  

Invite students to consider how they would design an experiment to find out which treatment is most effective for binge-eating disorder: naltrexone-bupropion, behavioral weight loss (BWL) therapy, or both.

In this particular study ("a randomized double-blind placebo-controlled trial"), researchers used a 2 (drug vs. placebo) x 2 (BWL vs no therapy) between participants design. In their discussion, they note that, in retrospect, a BWL therapy group alone would have been a good thing to have. The study was carried out over a 16-week period. Participants were randomly assigned to condition. Researchers conducting the assessments were blind to conditions.

Next ask students what their dependent variables would be.

The researchers had two primary dependent variables. They measured binge-eating remission rates, with remission defined as no self-reported instances of binge eating in the last 28 days. They also recorded the number of participants who lost 5% or more of their body weight.

Ready for the results?

Percentage of participants who had no binge-eating instances in the last 28 days

	Placebo	Naltrexone-Bupropion
No therapy	17.7%	31.3%
BWL therapy	37.%	57.1%

Number of participants who lost 5% or more of their body weight

	Placebo	Naltrexone-Bupropion
No therapy	11.8%	18.8%
BWL therapy	31.4%	37.1%

As studies that have evaluated treatments for other psychological disorders have found, medication and psychotherapy combined are more effective than either alone.

If time allows, you can help students gain a greater appreciation for how difficult getting participants for this kind of research can be. Through advertising, the researchers heard from 3,620 people who were interested. Of those, 972 never responded after the initial contact. That left 2,648 to be screened for whether they would be appropriate for the study. Following the screening, only 289 potential participants were left. Ask students why they think so few participants remained. Here are the top reasons: participants did not meet the criteria for binge-eating disorder (715), participants decided they were not interested after all (463), and participants were taking a medication that could not be mixed with naltrexone-bupropion (437). Other reasons included but not limited to having a medical condition (could impact study’s results), they were already in a treatment program for weight loss or binge-eating disorder (would not be a sole test of these treatments), or they were pregnant or breast-feeding (couldn’t take the drugs). After signing the consent form and doing the initial assessment, another 153 were found to have not met the inclusion criteria. That left 136 to be randomly assigned to conditions. Over the 16 weeks of the study, 20 participants dropped out on their own, and four were removed because of medical reasons. It took 3,620 people who expressed interest to end up with data from 112 participants.

There is no information in the article about whether participants who were not in the drug/psychotherapy group were offered—after the study was over—the opportunity to experience the combined treatment that was so effective. Ethically, it would have been the right thing to do.

References

Grilo, C. M., Lydecker, J. A., Fineberg, S. K., Moreno, J. O., Ivezaj, V., & Gueorguieva, R. (2022). Naltrexone-bupropion and behavior therapy, alone and combined, for binge-eating disorder: Randomized double-blind placebo-controlled trial. American Journal of Psychiatry, 1–10. https://doi.org/10.1176/appi.ajp.20220267

Mayo Clinic Staff. (2018, May 5). Binge-eating disorder. Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/binge-eating-disorder/symptoms-causes/syc-20353627

Sherman, M. M., Ungureanu, S., & Rey, J. A. (2016). Naltrexone/bupropion ER (Contrave): Newly approved treatment option for chronic weight management in obese adults. Pharmacy & Therapeutics, 41(3), 164–172.