Image credit: King's College London
Bulimia is characterized by behaviors such as controlling weight by severely restricting the amount of food consumed, followed by binge eating and, lastly, forced vomiting to remove the food from the body. This vicious behavior cycle becomes compulsive over time and is similar to that of addiction.
Eating disorders are usually connected with an abnormal attitude toward food or body image and can be triggered by hunger, stress, or emotional anxiety. Around 30 million people in the U.S. are affected by an eating disorder.
Bulimia typically develops in adolescence and is more common in women. The condition causes many complications, and it can lead to medical problems including anxiety and depression, kidney and heart failure, and it can result in 3.9 percent of people with the condition dying prematurely.
Psychotherapies, such as cognitive behavior therapy (CBT), are helpful in treating some people with bulimia. However, talking therapies are not always successful when used alone and are often used in combination with antidepressants.
Experimental brain stimulation valuable for neuropscychiatric conditions
Researchers are increasingly examining other treatment routes, including neuroscience-based technologies. Their aim is to test therapies that target the neural basis of eating disorders, which are thought to stem from problems with self-control and reward processing.
Negative mood might be responsible for triggering binge eating by altering the reward value of food and diminishing self-restraint.
Transcranial direct current stimulation (tDCS) is a brain stimulation therapy that delivers electrical currents to stimulate specific parts of the brain. While tDCS is regarded as an experimental form of brain stimulation, studies have suggested that it might be valuable for treating neuropsychiatric conditions such as anxiety, depression, chronic pain, and Parkinson's disease.
Compared with other brain stimulation techniques, tDCS is noninvasive, painless, safe, cheap, and easily portable. The therapy also has very few side effects, with the most common reported to be a slight tingling or itching on the scalp.
An area at the front of the brain, called the dorsolateral prefrontal cortex (DLPFC), is involved in self-control and associated with reward processing.
Previous research by the team, from King's College London in the United Kingdom, found that repetitive transcranial magnetic stimulation of the DLPFC decreased food cravings and binge eating episodes in people with bulimia after one session. Furthermore, stimulating the DLPFC with tDCS has produced therapeutic effects in obese individuals, food cravers, and people with anorexia nervosa and binge eating disorder.
Participants' urge to binge eat significantly reduced after tDCS
The new study, published in PLOS One, aimed to evaluate whether stimulation of the DLPFC with tDCS would be beneficial for people with bulimia - an area that had not yet been explored.
A total of 39 adults received treatments of tDCS and placebo tDCS with 48 hours between these sessions. Questionnaires took place before and after each treatment to determine the participants' urge to binge, and to detect concerns about weight, shape, and food intake, and assess self-control and self-esteem levels.
The team found that the electrical brain stimulation decreased the participants' urge to binge eat and increased self-control levels when compared to the placebo stimulation. In fact, after tDCS stimulation, baseline scores on the urge to binge eat scale fell by 31 percent.
Participants were provided with a decision-making task in which they had to make a choice between a small amount of money that was available immediately, and a large amount of money available in 3 months.
Following the tDCS session, participants were more likely than the placebo group to withhold gratification and choose the money available in 3 months. This action exhibits more self-controlled decision-making by waiting for later, larger rewards, instead of opting for the sooner, smaller gains.
Brain stimulation technique could potentially be self-administered
"Our study suggests that a noninvasive brain stimulation technique suppresses the urge to binge eat and reduces the severity of other common symptoms in people with bulimia nervosa, at least temporarily," says Maria Kekic, first author of the study.
"We think it does this by improving cognitive control over compulsive features of the disorder," she adds.
"Although these are modest, early findings, there is a clear improvement in symptoms and decision-making abilities following just one session of tDCS. With a larger sample and multiple sessions of treatment over a longer period of time, it is likely that the effects would be even stronger. This is something we're now looking to explore in future studies."
"The advantage of tDCS is that it's much less expensive and more portable than other brain stimulation techniques, which raises the prospect of one day offering treatment that could be self-delivered at home by patients with bulimia," notes Ulrike Schmidt, senior author of the study and a professor of eating disorders at King's College London.
"This could either be as an addition to talking therapies such as CBT to improve outcomes, or as a stand-alone alternative approach," she concludes.