Researchers have reported a 12-week clinical test of a combination therapy that greatly reduced episodes of binge eating in people with binge-eating disorder (BED) and co-existing obesity.

BED is defined by recurrent binge eating—typically, eating unusually large quantities while experiencing loss of control—without accompanying behaviors such as purging to compensate for weight gain (which is seen in bulimia nervosa). BED is strongly associated with obesity, but has distinct psychological and neurobiological features, notes the team that conducted the newly reported trial. They also note that BED is highly persistent, and often goes undiagnosed and untreated. And “those who do seek help rarely receive the very few evidence-based treatments,” they add.

Led by Carlos M. Grilo, Ph.D., of the Yale University School of Medicine, the team, which included Cenk Tek, M.D., a 2009 and 2006 BBRF Young Investigator, recruited 141 people diagnosed with both BED and obesity. Of these, 83% were female, 76% were White, and 69% were college-educated; the average age was about 43.5 years, and the average BMI (body mass index) was 38.6 (obesity is defined as a score of 30 and above). The study appeared in the American Journal of Psychiatry.

Participants were randomly assigned to receive one of three treatments for 12 weeks (47 in each group). One group received cognitive behavioral therapy (CBT), a second group received the drug lisdexamfetamine (50-70mg/day), and the third group received both CBT and lisdexamfetamine.

Past trials have found that CBT for BED reliably results in roughly half of patients attaining a remission of binge-eating symptoms by posttreatment (i.e., zero episodes of binge eating over a month’s time), along with significant improvements in associated eating-disorder psychopathology. In other research trials, CBT has demonstrated superiority for reducing binge eating compared to other treatments including behavioral weight-loss therapies and antidepressants. While reducing binge eating, CBT does not help with weight loss. Many people with BED do not have obesity, but, the researchers noted, “obesity and weight loss are frequent concerns and goals of most treatment-seeking patients with BED.”

Lisdexamfetamine (LDX) is the sole pharmacological treatment approved by the FDA for treating BED. It is thought to impact the dopamine and norepinephrine neurotransmitter systems that play important roles in regulating eating and reward. Like CBT, LDX has been found in clinical trials to help roughly half of BED patients reduce binge eating episodes. But the medicine is approved only for those judged to have moderate-to-severe BED, and there remains uncertainty about the drug’s effects on weight. It seemed logical to the team to test LDX in combination with CBT, in part because of preliminary evidence that LDX can reduce weight while limiting binge eating episodes.

In the 12-week trial, CBT was delivered in individual hourlong sessions by trained and supervised psychologists. The first phase of CBT involves establishing a collaborative therapeutic relationship, educating patients about factors thought to maintain binge eating (including unhealthy restraint and unstructured eating, as well as body-image disturbances) and training to identify unhealthy eating behaviors and working toward normalized eating patterns. A second phase involves cognitive restructuring, as patients learn to identify and challenge thoughts contributing to their binge eating behaviors, and how to cope with and overcome binge-eating triggers. A final phase seeks to consolidate skills and prevent behaviors leading to relapse.

In all three treatment groups, binge-eating episodes were significantly reduced. But the most important result of the trial was clear evidence that the combination of CBT and LDX yielded superior results. In fact, those taking LDX while receiving concurrent CBT had a 96% reduction in the frequency of binge-eating episodes, with 70% achieving remission (no episodes for the past month), assessed when treatments ended. The group receiving CBT alone reduced their binge eating episodes by an impressive 89%, with 45% achieving remission. Those in the LDX-only group had 80% fewer binge eating episodes with 40% achieving remission.

A significant factor in favor of combined treatment was the that CBT alone did not help patients reduce weight. When CBT was combined with LDX, an average weight loss of about 5% was attained, with 42% achieving a weight loss of 5% or greater. Weight loss in BED, particularly among those with obesity, is known to be difficult, the team noted, and this appears to be an important factor for patients and practitioners to consider regarding the relative value of the combined treatment, the researchers said.

One reason the team considers the superior results seen with this specific combination therapy to be important is that while a number of other combinations involving CBT and medications have been previously tested, most have failed to find added benefits. Previously, one medication (topiramate) enhanced both binge eating and weight outcomes, but it could not be tolerated by a significant portion of patients, leading to high rates of treatment discontinuation.

The reason for the superiority of CBT plus LDX is not known, but the researchers suggested they likely operated via distinct mechanisms. CBT, they said, might be “reducing unhealthy restraint and unstructured eating, while addressing the core body-image disturbance,” with LDX addressing “eating regulation and reward effects,” perhaps helping to reduce impulsivity.

Future trials should test the combination therapy in more diverse populations, the team said, and in patients with BED who do not also have obesity. It is also unknown how long-lasting the benefits of the treatments are beyond the 12 weeks of observation in the current study. CBT benefits tend to be enduring, but the durability of LDX benefits are not yet fully known.