The technique – known as deep brain stimulation (DBS) – involves a device similar to a pacemaker being implanted into the patient's brain, and while the pilot study was primarily intended to assess the safety of the procedure, at least half of the patients who took part in the study showed improvements in mood and Body Mass Index (BMI), leading researchers to hope that larger trials will confirm the effectiveness of the technique in treating patients with severe anorexia.
DBS is currently used to treat several neurological disorders, including Parkinson's disease and chronic pain, and investigations are underway investigating its use for treating other disorders, such as depression and epilepsy, but this is the first time that it has been used to treat patients with severe anorexia which has not responded to other treatment. Although the treatment requires some surgery, it is minimally invasive, and completely reversible.
Researchers based at the Krembil Neuroscience Centre and University Health Network in Canada used Magnetic Resonance Imaging (MRI) to identify a specific area of the brain – a bundle of white matter below the corpus callosum, the thick bundle of nerve fibres which divides the left and right sides of the brain – which has previously been used for DBS in patients with depression. Once the target area had been identified, electrodes were then implanted into the area and connected to a pulse generator, which was implanted under the skin. The device was activated ten days after it had been implanted, with the researchers carefully measuring acute changes in the patients' mood and anxiety levels to determine the correct level of stimulation.
At the time of surgery, the female patients were aged between 24 and 57, and had been suffering from anorexia for between four and 37 years. Although the pilot study was primarily intended to assess the safety of the procedure in this patient group, the researchers also recorded changes in the participants' mood, compulsive behaviour and abnormal eating patterns, which they measured using standardised tests. The treatment appeared to be relatively safe, with just one patient experiencing a serious adverse event following the treatment, a seizure which took place about two weeks after the initial operation, which was related to a metabolic disorder the patient was suffering as a result of her anorexia.
In the weeks before surgery, 5 of the 6 patients had recently been attending inpatient treatment, which had resulted in some weight gain. After two months, all six patients had lost weight, returning to their usual baseline, in line with the researchers' expectations – studies of DBS for patients with depression have usually observed a latency period of a few months before the treatment becomes effective. However, three months after the treatment, this pattern began to reverse, with five of the six patients stabilising or gaining weight, relative to two months after the operation. After nine months, three patients were maintaining a higher weight than before the treatment started – the longest period of sustained increase in weight that any of them had achieved since the onset of illness. Around half of the patients also experienced improvements in their mood or reduced obsessive-compulsive behaviour.
According to Dr Andres Lozano, a leading neurosurgeon in the field of DBS, and one of the lead researchers, the results are particularly encouraging because they seem to point to a genuine therapeutic effect, rather than a placebo or hunger-increasing effect, explaining that "The initial weight loss argues against a primary effect of DBS on hunger, appetite, or metabolic rate. It also suggests that there is little in the way of a placebo-related benefit to the surgery." Dr Lozano adds that, "The finding of improvements in mood and anxiety in patients who were still underweight is especially striking, in view of the well known poor response of underweight patients to conventional pharmacotherapies or psychotherapies."
Anorexia has one of the highest mortality rates of any psychiatric disorder, and is among the most common psychiatric disorders in young women aged 15 – 19 years. Treatment usually focuses on behavioural change, but up to 20% of patients derive no benefit from the available treatment and are at risk of dying prematurely from the disease.
In a linked Comment, Professor Janet Treasure and Professor Ulrike Schmidt of King's College London's Institute of Psychiatry write, "the personal and social costs of eating disorders in general are large, and nowhere are these more evident than in patients with severe and enduring anorexia nervosa. New effective treatments for these patients are sorely needed…the findings of this proof-of-concept study are promising and will give hope to patients with especially pernicious forms of the disorder and their families. The fact that the procedure was associated in some patients with improvements in affective and obsessional symptoms is of key importance, since such improvements will go some way towards reassuring patients that DBS is not just another treatment designed to fatten them up without making them feel better."
Journal
The Lancet