Stimulating parts of the brain with magnetic fields appears to reduce symptoms and improve decision-making in people with anorexia nervosa, according to the findings of new study we conducted at King’s College London.
Anorexia is associated with a morbid fear of fatness, extreme food restriction and dangerously low body weight. About 4% of women will suffer from anorexia at some point in their life. It has one of the highest mortality rates of all psychiatric illnesses, with about one in five people dying prematurely as a result of the disorder.
The longer a person suffers from anorexia, the more entrenched it becomes and the harder it is to treat. At best, recovery rates from talk therapies are only 20-30%. And there is not much evidence that drug therapies, such as antidepressants and antipsychotics, are effective. We desperately need new treatments.
Re-wiring the brain
Brain imaging studies show that people with anorexia have altered neurocircuitry. New treatments that target these neural pathways are urgently needed. In our study, we investigated the potential of a non-invasive brain stimulation technique called repetitive transcranial magnetic stimulation (rTMS) in improving symptoms of anorexia.
rTMS has been approved by NICE (National Institute for Health and Care Excellence) for treating depression. It has also shown potential in reducing symptoms of eating disorders. It’s safe, relatively painless and is very rarely associated with severe side-effects.
rTMS applies magnetic pulses to the brain and these pulses are able to alter neural activity. The therapeutic effects of rTMS in psychiatric disorders are thought to occur as a result of “neuroplasticity” – the malleable nature of the brain. The gentle magnetic stimulation helps the brain form new neural connections.
For our research, we got 49 people with anorexia to complete food exposure and decision-making tasks, both before and after a single session of either real or placebo rTMS. The rTMS was applied to the dorsolateral prefrontal cortex, an area of the brain thought to be involved in some of the self-regulation difficulties associated with anorexia. Symptoms and decision-making were measured immediately before and after rTMS, and symptoms of anorexia were also measured 20 minutes and 24 hours after the session.
The food exposure task sought to provoke symptoms by asking participants to watch a two-minute film of people eating appetising food, such as chocolate and crisps, while the same items were in front of them. Participants then had to rate the perceived smell, taste, appearance and urge to eat these foods.
Decision-making was measured using a hypothetical monetary reward task. Participants had to choose between a smaller, variable amount of money (£0-£99) available immediately, and a larger, fixed amount (£100), available after four different time delays (a week, month, year or two years). An inclination to choose the smaller, sooner reward is thought to reflect impulsivity, while waiting for the larger, later reward demonstrates an ability to delay gratification.
Compared with those who received placebo rTMS, we found that participants who had just one session of real rTMS reported reduced symptoms of anorexia (for up to 24 hours), specifically the urge to restrict food intake, levels of feeling full and levels of feeling fat.
Also, a single session of real (but not placebo) rTMS encouraged more prudent decision-making in people with anorexia. That is, following real rTMS, participants waited for larger, later rewards demonstrating improved self-control.
Most of the participants (90%) said they would consider having 20 daily sessions of rTMS, suggesting it is a viable treatment for people with anorexia.
Our findings suggest that rTMS may reduce symptoms of anorexia by improving control over compulsive features of the disorder, such as food restriction. Although our findings were only a statistical trend, there is a clear improvement in symptoms and decision-making following just one session of rTMS. It’s likely that with a larger sample and multiple sessions of rTMS these effects would be even stronger.
These preliminary findings support the potential of brain-directed treatments for anorexia. Given the promising findings from our study, we are now assessing whether rTMS has longer-lasting therapeutic benefits. We are also using brain imaging to try and understand the neural mechanisms of these promising results.