Dominika Karaszewska, PhD Candidate at the department of psychiatry of Amsterdam UMC, performed the first world-wide meta-analysis on the effects of deep brain stimulation (DBS) in patients with treatment-refractory anorexia nervosa (AN). In this research, supervised by Damiaan Denys and Roel Mocking, she found statistically large beneficial effects on weight restoration, quality of life, and reduction of psychiatric symptoms.

Anorexia nervosa has an alarming mortality rate. About 20% of AN patients remain treatment-refractory to psychotherapy and pharmacological treatment aimed at weight restoration. To improve this grim perspective, there is an urgent need for novel treatment options. DBS is a promising new treatment and already established as an effective treatment for other diseases, such as Parkinson’s disease, essential tremor, and obsessive-compulsive disorder (OCD).

Serendipity: more than a good surprise

The idea of treating AN with DBS came from serendipitous positive effects that were noted in earlier DBS studies for major depressive disorder (MDD) and OCD, while the patients simultaneously suffered from comorbid AN. Follow-up research by Amsterdam UMC psychiatrist Marloes Oudijn showed not only a decrease of the MDD or OCD symptoms, but also an improvement of the AN symptoms, including cognitive and emotional symptoms. Patients presented significant improvement in BMI (body mass index) and decreased anxiety and distress in relation to weight gain.

Objective vs. subjective outcomes

For this first meta-analysis, Karaszewska included four studies with a total of 56 patients with AN. A significant positive effect of deep brain stimulation on BMI was found in the entire group, with a large effect size of 1.13 (Hedges's g). The effect was also observed in the reduction of psychiatric symptoms (effect size = 0.89) such as depressive symptoms, obsessive-compulsive symptoms, symptoms of anxiety, and eating disorder symptoms, and an improvement in quality of life (effect size = 0.86).

Statistically large beneficial effects

In this analysis, no indications of publication bias were found. In addition, there were no statistical indications for the presence of heterogeneity. The quality of the evidence for the positive effects of DBS on the more objective outcome (BMI) was assessed as moderate according to GRADE. Finally, the quality for the more subjective results (the positive effects of DBS on psychiatric symptoms) was assessed as low. Thus, results suggest that DBS has statistically large beneficial effects in severe and life-threatening treatment-refractory AN. More naturalistic studies are needed to determine the clinical relevance of these outcomes.