Binge-eating disorder is the most prevalent eating disorder in the United States, but previous studies have presented conflicting views of the disorder's duration and the likelihood of relapse. A new five-year study led by investigators from McLean Hospital, a member of the Mass General Brigham health care system, showed that 61% and 45% of individuals still experienced binge-eating disorder 2.5 and 5 years after their initial diagnoses, respectively. These results contradict previous prospective studies that documented faster remission times, according to the authors.

"The big takeaway is that binge-eating disorder does improve with time, but for many people it lasts years," said first author Kristin Javaras, DPhil, Ph.D., assistant psychologist in the Division of Women's Mental Health at McLean.

"As a clinician, oftentimes the clients I work with report many, many years of binge-eating disorder, which felt very discordant with studies that suggested that it was a transient disorder. It's very important to understand how long binge-eating disorder lasts and how likely people are to relapse so that we can better provide better care."

The results were published May 28 in Psychological Medicine.

Binge-eating disorder, which is estimated to impact somewhere between 1% and 3% of U.S. adults, is characterized by episodes during which people feel a loss of control over their eating. The average age of onset is 25 years.

While previous retrospective studies, which rely on people's sometimes-faulty memories, have reported that binge-eating disorder lasts seven to sixteen years on average, prospective studies tracking individuals with the disorder over time have suggested that many individuals with the disorder enter remission within a much smaller timeframe—from one to two years.

However, the researchers noted that most previous prospective studies had limitations, including a small sample size (<50 participants), and they were not representative because they focused only on adolescent or young-adult females, most of whom had BMIs less than 30, whereas around two-thirds of individuals with binge-eating disorder have BMIs of 30 or more.

To better understand the time-course of binge-eating disorder, the researchers followed 137 adult community members with the disorder for five years. Participants, who ranged in age from 19 to 74 and had an average BMI of 36, were assessed for binge-eating disorder at the beginning of the study and re-examined 2.5 and 5 years later.

After five years, most of the study participants still experienced binge-eating episodes, though many showed improvements. After 2.5 years, 61% of participants still met the full criteria for binge-eating disorder at the time the study was conducted, and a further 23% experienced clinically significant symptoms, although they were below the threshold for binge-eating disorder.

After 5 years, 46% of participants met the full criteria and a further 33% experienced clinically significant but sub-threshold symptoms. Notably, 35% of the individuals who were in remission at the 2.5-year follow-up had relapsed to either full or sub-threshold binge-eating disorder at the 5-year follow-up.

The criteria for diagnosing binge-eating disorder have changed since the study was conducted, and Javaras notes that under the new guidelines, an even larger percentage of the study's participants would have been diagnosed with the disorder at the 2.5 and 5-year follow-ups.

Javaras added that because participants in the study were community members who may or may not have been receiving treatment, rather than patients enrolled in a treatment program, the study's results are more representative of binge-eating disorder's natural time-course.

When comparing this community sample to those in treatment studies, treatment appeared to lead to faster remission, suggesting that people with binge-eating disorders will benefit from intervention. There are major inequities in who receives treatment for eating disorders, according to Javaras.

Though there was variation among participants in the likelihood of remission and how long it took, the researchers were unable to find any strong clinical or demographic predictors for duration of the disorder.

"This suggests that no one is much less or more likely to get better than anyone else," said Javaras.

Since the study ended, the researchers have been investigating and developing treatment options for binge-eating disorder, and examining screening methods to better identify individuals who would benefit from treatment.

"We are studying binge-eating disorder with neuroimaging to get a better understanding of the neurobiology involved, which could help enhance or develop new treatments," said Javaras.

"We are also examining ways to catch people earlier, because many don't even realize they have binge-eating disorder, and there is a major need for increased awareness and screening so that intervention can begin earlier."